Loss of control

Investigation summary

What happened

On the morning of 25 February 2025, an Agusta A109E helicopter was conducting a marine pilot transfer operation on the inbound bulk carrier Star Coral at Blossom Bank pilot boarding ground, about 200 km north‑east of Mackay, Queensland.

At 0901 local time, during take‑off from the ship with 2 pilots on board, the helicopter developed severe vibrations. The pilots discontinued the take-off but their attempts to recover control of the helicopter were unsuccessful. The helicopter came to rest in an upright position on the helideck, having spun more than 90° counterclockwise from its initial heading, and sustaining substantial damage. The pilots and ship’s crew were unharmed.

What the ATSB found

The investigation did not identify any airworthiness issues with the helicopter and it was considered that the loss of control was not attributable to a mechanical issue. 

The ATSB found that the vibration was likely the result of the helicopter entering ground resonance, a phenomenon that dissipates when airborne, while it was in the process of departing from the ship. The discontinuation of the take‑off, after the onset of the vibration, probably resulted in the loss of control and subsequent damage to the helicopter.

What has been done as a result

The operator has added new guidelines on ground resonance to its procedures. The guidelines include procedures for recognising and recovering from ground resonance and feature case studies and video resources for training purposes. 

The operator has also developed an updated procedure for training and checking flight briefings that will include confirming the roles of each pilot, procedures for transferring aircraft control between pilots, and actions to be followed in the event of an actual emergency.

Safety message

The occurrence highlights the dangers of ground resonance, a potentially catastrophic phenomenon that can occur in helicopters with fully articulated rotor systems. Typically, the onset of ground resonance is sudden and if the pilot does not take immediate corrective action, a loss of control can rapidly occur. 

The occurrence also highlights the importance of proper coordination between a helicopter’s pilots when responding to abnormal or emergency situations. This is particularly pertinent for situations where the pilot flying is not the pilot in command. Ideally, the pilots’ individual roles and responsibilities for emergency response and flying duties should be well established prior to the flight. 

The investigation

The occurrence

At about 0730 local time on 25 February 2025, the 229 m bulk carrier Star Coral arrived at the Blossom Bank pilot boarding ground, about 200 km north‑east of Mackay, Queensland (Figure 1). The ship waited to embark a coastal marine pilot by helicopter for its inbound transit of the Great Barrier Reef via Hydrographers Passage.[1] It was in ballast and bound for Hay Point to load coal. 

Figure 1: Blossom Bank pilot boarding ground and Hydrographers Passage

Source: Australian Hydrographic Office, annotated by the ATSB

Meanwhile, at Mackay Airport, a twin‑engine Agusta A109E helicopter, operated by Flyon Helicopters and registered VH‑XUM (XUM), with 2 pilots on board, embarked the marine pilot scheduled to conduct the ship’s pilotage. The marine pilot transfer (MPT) flight to Star Coral was the first scheduled for the helicopter and its pilots that day. These flights were normally conducted as a single‑pilot operation. However, on this occasion, the pilot flying, a pilot recently engaged by the operator under its ‘in‑command‑under supervision’ (ICUS)[2] program, was under the supervision of a company check pilot (pilot supervising). 

The pilots’ plan was to transfer Star Coral’s marine pilot and then proceed to a nearby outbound ship to collect its marine pilot for return to Mackay.

At 0759, the helicopter departed Mackay Airport under the control of the pilot flying. En route, the pilots established communication with Star Coral’s master via VHF[3] radio. The master advised that the ship was rolling about 3° on its inbound heading due to a 2 m south‑easterly swell. Subsequently, the pilots requested the master to reposition the ship on a heading[4] of 270° to reduce rolling. At 0853, the pilot flying landed the helicopter on the ship’s helideck, situated on the number 5 cargo hold hatch cover (Figure 2). The marine pilot exited the helicopter and proceeded to the ship’s bridge. 

Figure 2: Landing position of VH-XUM aboard Star Coral

This figure is a representation of the helicopter’s orientation relative to the wind during the take‑off. Source: Flyon Helicopters and Star Coral, annotated by the ATSB

Meanwhile, the helicopter remained on the helideck at flight idle[5] while its pilots radioed the outbound ship’s pilot to coordinate the transfer. After some discussion, the pilots elected to keep the helicopter on the deck of Star Coral until the outbound ship had departed the compulsory pilotage area.

After about 5 minutes, as the 2 ships were about to pass each other, the helicopter pilots began conducting their pre‑take‑off checks. The pilots observed a 20 to 28 knot headwind (relative to the helicopter) and noted that the ship was rolling less than 2°. The pilot flying conducted a brief for a performance category 1[6] take‑off, which involved establishing the helicopter in a hover 35 ft above deck height before departing. Both pilots later recalled that everything seemed normal as the take‑off checks were completed. 

At about 0900, the pilot flying raised the collective[7] and observed the engine torques increasing through 50%. The pilot flying recalled the aircraft became light on its oleos as though it was ‘right at the point of lifting off’. Meanwhile, the pilot supervising was observing the outbound ship passing. A few seconds later, both pilots felt a sudden and substantial vibration. 

The pilot supervising immediately looked down at the controls and recalled that the pilot flying was holding the cyclic[8] in an abnormally aft position. Concerned that the main rotor might have struck the tail boom, the pilot supervising decided to assume control of the helicopter and took hold of the cyclic and collective unannounced. Meanwhile, the pilot flying was still attempting to lift off, unaware of the pilot supervising’s decision to take control. The pilot supervising recalled that the pilot flying had centred the cyclic and ‘must have’ lowered the collective by the time the pilot supervising took hold of the controls. In contrast, the pilot flying stated that the pilot supervising rapidly lowered the collective after the vibration started, causing the aircraft to descend from being light on its oleos and bounce heavily on the helideck.

Moments later, the cyclic became uncontrollable as the vibrations suddenly worsened into a violent, vertical oscillation of the airframe. The pilot supervising tried to stabilise the helicopter but was unable to control the cyclic movement. Subsequently, the pilot supervising elected to shut down the engines. 

The pilot supervising initially struggled to reach the engine mode switches (located on the centre console) due to the severe vibrations but subsequently managed to shut down engine number 2. The vibrations slightly eased and moments later, they were able to also shut down engine number 1. The vibration dissipated and the helicopter came to rest in an upright position on the helideck, having spun more than 90° counterclockwise from its initial heading. The sequence, from the attempted take‑off to shut‑down occurred within a period of about one minute.

Soon after, the pilots exited the wreckage and inspected the damage. The tail rotor was separated from the helicopter and had come to rest on the main deck between cargo hatches 4 and 5. Items of debris, including main rotor fragments, laid scattered on the deck along with some hydraulic fluid pooled beneath the substantially damaged fuselage (Figure 3).  

Figure 3: Helicopter wreckage 

Source: Star Coral

Apart from a thumb sprain to the pilot supervising and some bruising to both pilots’ upper leg areas, where they had been struck by the cyclic, neither were significantly injured and no‑one on board Star Coral was injured.

Context

Helicopter information

The helicopter was an Agusta A109 E variant, manufactured in 2006 and issued serial number 11684. It was registered in Australia in 2006 and began services under the operator’s Air Operator’s Certificate (AOC) in 2023. 

The Agusta A109E is a multipurpose helicopter equipped with 2 Pratt & Whitney PW206‑C turbine engines. It has a fully articulated 4‑blade main rotor system, a 2‑blade tail rotor and retractable tricycle landing gear. Able to carry up to 7 occupants, it has a maximum allowable take‑off weight of 2,850 kg. 

The helicopter was able to perform flight performance class 1 operations by adherence to Category A procedures[9]. While the helicopter was normally operated from the right crew seat, it was fitted with dual controls. A left seat‑approved pilot in command (PIC) was permitted to occupy either seat during training flights. Each set of controls could not be operated independent of the other. 

The helicopter’s wreckage was recovered from the ship 2 days after the incident and transported to a secure hangar at Mackay Airport. Prior to its removal, photographs of the wreckage and the accident area were taken. There were no indications that the main rotor or tail rotor had struck any part of the ship during the accident. 

Based on its inspections, the operator advised that no engine faults or exceedance alarms had been recorded by the helicopter’s electronic engine management systems. Additionally, no faults or defects had been reported by any of XUM’s pilots or maintainers leading up to the occurrence flight. 

Post-accident activities

There was no recorded flight data available to determine the flight control inputs and their effect on the motion of the helicopter during the occurrence.[10] The pilots’ accounts, a witness statement from the master of Star Coral and photographs of the wreckage were the main sources of evidence. 

The ATSB also sought the manufacturer’s input for this occurrence. The manufacturer advised that its preliminary assessment of the available evidence suggested that the helicopter damage appeared consistent with a ground resonance phenomenon (see the section titled Ground resonance).

The licenced maintenance organisation for XUM carried out an examination of the wreckage at the Mackay hangar. On advice from the manufacturer, the examination included inspection of specific components commonly associated with ground resonance. These included main rotor dampers, landing gear struts and tyres. The operator advised the ATSB that the inspection did not identify any airworthiness issues that may have contributed to the occurrence. The operator did not provide the inspection report or findings to the manufacturer for its assessment.

Pilot flying 

The pilot flying obtained a New Zealand commercial helicopter licence (CPL) in 2011 and started flying commercially in 2014. They converted their CPL over to an Australian CPL in 2016 and held a grade 2 flight instructor rating and a class 1 aviation medical certificate. They had experience flying both single and twin-engine helicopters in various operations. Prior to joining the operator’s in‑command‑under‑supervision (ICUS) program in September 2024, they had no previous experience on the A109E, or with marine pilot transfers (MPT). 

Under the ICUS program, the pilot was required to accrue 200 hours on the A109E before they could be assessed to fly the helicopter unsupervised on daytime VFR[11] MPT operations. At the time of the occurrence, the pilot had completed the operator’s training requirements and accrued around 50 hours flight time on the A109E. They had also been cleared to conduct unsupervised MPT operations on single‑engine Eurocopter AS350 helicopters.

Pilot supervising

The pilot supervising was the operator’s head of flying operations and held an air transport pilot (helicopter) licence, issued in 2014, and a class 1 aviation medical certificate. They were approved under the operator’s training and checking system to conduct check and supervision flights on the A109E.

The pilot supervising had been flying helicopters for 26 years in various operations and had accumulated over 10,000 hours flying time, including 3,800 hours in the A109E. They first started MPT operations in 2007 and commenced working with the operator in December 2016.   

Star Coral

Star Coral was built in 2009 by Jansu Newyangzi Shipbuilding, China, registered in The Bahamas and classed with Bureau Veritas. The ship was owned by Panormos Shipping, The Bahamas, and managed and operated by Charterwell Maritime, Greece. 

At the time of the occurrence, the 229 m ship had a mean draught of 6.51 m and the helideck height was about 18 m above the waterline.   

In a written witness statement, the master reported that:

• shortly after the helicopter started to take off, it began to pound on the helideck before it spun and the tail rotor separated

• during the sequence, the helicopter became airborne for no more than 2 seconds.

Ground resonance

Ground resonance can be defined as a vibration of large amplitude resulting from a forced or self‑induced vibration of a helicopter in contact with the ground.[12] The phenomenon is normally associated with helicopters equipped with fully articulated main rotor systems consisting of 3 or more rotor blades. It is more common on helicopters with sprung landing gear than those with skids. Typically, ground resonance occurs during landing, take‑off and ground manoeuvres.[13]

In fully articulated rotor systems, drag hinges allow each blade to advance or lag in the plane of rotation to compensate for the stresses caused by the acceleration and deceleration of the rotor hub. Such rotor systems are typically fitted with lead‑lag dampers to limit the extent of this movement and help prevent excessive vibrations. However, if for any reason one or more of the blades assumes a dragged position different to the others, the blades will move out of phase and the rotor will become imbalanced, transmitting an oscillation throughout the entire airframe.[14]

The risk of ground resonance arises when the unbalanced forces in the rotor system cause the fuselage to oscillate on its landing gear at or near its natural frequency. Ground resonance will occur if the helicopter’s damping systems are unable to compensate for the oscillation.[15] Unless corrective action is taken, the amplitude of the oscillation will increase until the helicopter becomes uncontrollable.[16] Ground resonance can also be induced when the helicopter is in light contact with the ground, if the landing gear oscillation frequency is in sympathy with the rotor head vibration.[17]

Ground resonance is commonly precipitated by the helicopter making hard or asymmetric contact with the ground, landing on a slope or sudden control movements by the pilot.[18] It can also result from other factors such as improper blade balancing and tracking, or damage to any of the blades.[19] Hard contact with the ground by some part of the landing gear when the main rotor is in an unbalanced state can further aggravate the condition.[20]

Additionally, improper maintenance of the helicopter’s main rotor and fuselage damping systems, or incorrect tyre pressures, can induce or worsen ground resonance.[21]

Flight control inputs that may induce ground resonance typically involve sudden control movements or a mishandling of the cyclic that causes the fuselage to bounce.[22]

The helicopter manufacturer advised that the application of certain cyclic commands, such as extreme aft cyclic input, could theoretically reduce the main rotor damper effectiveness in respect to the damping action on the blades’ regressive lead‑lag dynamic.

Recovery technique

The onset of ground resonance can be recognised by a rocking motion or oscillation of the fuselage while on the ground.[23] The United States Federal Aviation Administration (FAA) Helicopter Handbook[24] documented 2 widely accepted recovery techniques: 

• if the condition arises when there is insufficient rotor speed for take‑off, the only option is to lower the collective to reduce the pitch of the blades. The rotor rpm[25] should also be reduced as soon as possible.[26]

• If the rotor speed is in the normal operating range for flight, the Helicopter Handbook recommends lifting the helicopter off the ground to allow the rotor blades to rephase themselves automatically. 

Additionally, the FAA cautioned that:

If a pilot lifts off and allows the helicopter to firmly re‑contact the surface before the blades are realigned, a second shock could move the blades again and aggravate the already unbalanced condition. This could lead to a violent, uncontrollable oscillation.  

In practice, a pilot experiencing ground resonance typically has seconds to identify the condition and take corrective action. 

Similar occurrences

The ATSB reviewed several investigation reports relating to previous A109E accidents attributed to ground resonance. The incidents reviewed occurred outside of Australia between 2006 and 2025 and the contributing factors were found to be operational. Technical factors which may have caused or exacerbated ground resonance were not identified. 

Details of the previous incidents bear similarity to the occurrence involving XUM, particularly in respect to subsequent damage to the helicopter (Figure 4). 

Figure 4: Previous occurrences of ground resonance involving the Agusta A109E

Source: Leonardo Helicopters

Flight manual procedures

The A109E rotorcraft flight manual (RFM) listed fault conditions and corrective actions for emergencies and malfunctions that might occur during take‑off.

The RFM included the caution below for ground resonance within the normal flight procedure for take‑off. This was not part of the emergency and malfunction procedures.

The RFM procedure for ground resonance was consistent with recovery techniques published by the FAA. The RFM reference to the helicopter being ‘free of ground resonance’ was intended to indicate  that, like all helicopters, the A109E was designed and certified to applicable standards so that the rotor and fuselage systems do not vibrate at the same frequency under normal conditions.   

Operator procedures

As an AOC holder, the operator maintained a CASA‑approved[27] operations manual/exposition[28] to promulgate general policy and standardised procedures for MPTs on the A109E. The version of the operations manual current at the time of the occurrence was issued by the operator in November 2023.

Ground resonance

The operator’s normal procedures and emergency checklists for the A109E were derived from the RFM and did not contain any procedures related to ground resonance. 

Crew coordination in response to abnormal situations

While MPT flights were predominantly conducted by a single pilot, the helicopter was certified for operations with either a single pilot or 2 pilots. In either case, the normal procedure and emergency checklists remained the same, except that 2‑pilot checklist procedures were to be based on challenge and response. 

Normal handover and takeover procedures provided that:

In the case where the pilot flying (PF) is not the PIC and the PIC determines that the PF is not maintaining adequate control of the aircraft, the PIC may elect to take control, in which case they will signal their intention by saying ‘I have control’ upon which the PF will immediately relinquish control and the roles will reverse.

In abnormal or emergency situations, the PIC was responsible for ensuring the aircraft was flown and kept under control. The operations manual emphasised the importance of cockpit resource management (CRM) standards throughout the situation, in accordance with the below procedure:

Note: In the above procedures PM stands for ‘pilot monitoring’, NR refers to main rotor speed and IAS means indicated airspeed. 

In the context of rapidly escalating emergencies such as ground resonance, pilots have limited time to perform the procedure. 

Pilot in command responsibility during training flights

As the holder of a certificate that authorised air transport and aerial work operations, the operator was required to have in place a training and checking system (TACS). A training and checking manual (TACM) sets out policies and procedures for conducting training flights. It provided that a check pilot supervising ICUS training was to be the PIC. Check pilots were to ensure that pilots involved in training exercises were made aware of who was acting as the PIC through proper handover of control procedures. 

While an ICUS pilot might be considered the PIC for flight‑time logging purposes, the pilot supervising was deemed the PIC and responsible for the safety of the flight. The TACM stated that in the event of an actual emergency during flight training:

If the flight examiner or check pilot deems it necessary to take physical control of the aircraft at any stage after the occurrence of the emergency, then they shall do so in accordance with the hand‑over and take‑over procedures specified in the Operations Manual - Hand over and take‑over procedures.

The flight examiner or check pilot must be prepared and ready to assume physical control of the aircraft at any stage, particularly during critical manoeuvres such as during take‑off and landing.

As such, beyond the normal handover of control procedures, there were no special provisions in the TACM for the allocation of PIC responsibility and PF duties during ICUS flights. 

Briefings

For 2‑pilot operations or training flights, the operator’s procedures did not require pilots to brief who would assume PF duties in the event of an abnormal or emergency situation during critical phases of flight. 

Operational limits

Under the operator’s operations manual, the A109E was permitted to conduct daytime MPT operations up to a wind strength of 30 knots, with a maximum crosswind of 20 knots. The operational limit for ship’s pitch was 4° up and 2° down while the maximum permissible roll was 4°. The manufacturer did not have input into these operator‑defined limits. 

The pilots reported that the conditions at the time of the occurrence (20‍–‍28 knot headwind, 2° roll and minimal pitching) were within the operator’s limits for MPTs.

Safety analysis

Prior to the accident, VH‑XUM (XUM) made an uneventful landing on Star Coral and remained on the deck for several minutes without incident. There was no evidence that the helicopter was operating abnormally or experienced any instability during this period. 

Examination of the accident site did not reveal any evidence to suggest that the occurrence resulted from the main rotor or tail rotor striking the ship. Star Coral’s master reported that the tail rotor separated after the helicopter started contacting on the deck, indicating that contact with the tail boom by the main rotor was a consequential rather than causative factor. 

In that context, it is most likely that the helicopter encountered ground resonance. Assessment of the damage to the helicopter following the occurrence revealed significant similarities to that seen in previous A109E incidents attributed to this phenomenon. 

It is well established that ground resonance only arises when the helicopter is in contact with the ground. Both pilots asserted that the helicopter did not become airborne prior to the vibrations while the master reported that it became airborne for about 2 seconds. However, it is more likely this occurred after the vibration worsened and the helicopter started rebounding on the helideck. 

The exact cause of the vibration could not be determined. The possibility of causative operational factors such as flight control inputs or environmental factors could not be ruled in or out. 

Similarly, while the operator’s post‑accident inspection of the helicopter (including examination of its rotor and fuselage damping systems) did not reveal any apparent defects, causative technical factors could not be discounted.

However, the sudden lowering of the collective after the onset of the vibration likely aggravated the situation. The helicopter was almost certainly light on its oleos when the vibration began. Therefore, a sudden lowering of the collective would have caused the helicopter to come down firmly on the helideck. The United States Federal Aviation Administration (FAA) Helicopter Handbook describes that such an impact when the rotor is already in an unbalanced state can cause the rotor blades to move further out of phase, resulting in violent uncontrollable oscillations. This description is consistent with the occurrence sequence described by the pilots and the master. 

The pilots’ accounts of who lowered the collective differed. The recollection of the pilot flying that their intention was to lift the helicopter off the deck in response to the vibration was not consistent with a lowering of the collective. In contrast, the pilot supervising did not immediately identify the source of the vibration and later shut down the engines, believing the main rotor may have struck the tail boom. In this context, lowering of the collective would be a natural and expected response. Therefore, it is most likely that the pilot supervising lowered the collective while the pilot flying was attempting to lift the helicopter off the helideck.

In isolation, the immediate responses taken by each pilot following the sudden onset of the significant vibration were understandable. However, since the helicopter’s rotor speed was in the normal operating flight range, continuation of the take‑off would probably have resulted in the vibration dissipating (as detailed in the FAA Helicopter Handbook).

The operator had adequate procedures for responding to abnormal and emergency situations. However, the rapidly escalating nature of this occurrence meant that there was virtually no time to implement them. There was no requirement for the pilots to conduct a pre‑flight or pre‑take‑off brief about who would assume flying duties in the event of an emergency on take‑off. Therefore, the normal procedures for handover and takeover of control were assumed to apply.

However, the time between observing the vibrations and the loss of control severely limited the time available for a formal transfer of control between the pilots. As a result, neither of these procedures were followed and each pilot responded to the situation separately. 

Findings

From the evidence available, the following findings are made with respect to the loss of control during marine pilot transfer operations, involving an Agusta A109E, VH‑XUM and bulk carrier Star Coral, about 200 km north‑east of Mackay, Queensland, on 25 February 2025.

Contributing factors

• During take‑off, the helicopter likely experienced ground resonance, resulting in the rapid onset of significant vertical oscillations through the airframe.
• Discontinuing the take‑off after the onset of the vibration, with the rotor speed in the flight range, probably resulted in the loss of control and substantial damage to the helicopter.

Safety actions

Safety action by Flyon Helicopters 

Following this occurrence, the helicopter’s operator, Flyon Helicopters, established ground resonance guidelines for its pilots. Forming part of its exposition, the guidelines were purposed to raise awareness of ground resonance and provide information about how to recognise and respond to the phenomenon. They included response procedures and featured case studies and video resources. The procedures were to be implemented into the operator’s training framework for new and current pilots. 

Flyon Helicopters advised the ATSB that it also planned to implement an additional briefing procedure in its training and checking manual (TACM). The briefing is to be conducted by the training or checking pilot prior to any training or checking flight. It will include:

• the objectives and scope of the flight, including the intended lesson plan or sequence
• the training/checking outcomes
• the roles of each pilot, including the allocation of aircraft command responsibility
• procedures for transferring aircraft control between pilots
• actions to be followed in the event of an actual emergency
• procedures to be used in the simulation of emergencies
• procedures for the conduct of unusual operations
• the method to be used to simulate instrument flight conditions, if required
• human factors/non‑technical stills and threat and error management.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the pilots and operator of VH-XUM
• the master and manager of Star Coral
• the helicopter manufacturer, Leonardo Helicopters

References

Lemmens Y, Troncone E, Dutré S, Olbrechts T. (2012). Identification of Helicopter Ground Resonance with Multi-body Simulation, 28^th International Congress of the Aeronautical Sciences

United Kingdom Ministry of Defence, AP3456 Central Flying School Manual of Flying Vol 12 - Helicopters

Salini S N, Haradev G S, Ranjith M. (2020). Ground Resonance: Nonlinear Modelling and Analysis, 6th Conference on Advances in Control and Optimization of Dynamical Systems (ACODS), India

United States Federal Aviation Administration. (2019). Helicopter Flying Handbook

Schafer J. (1980). Helicopter Maintenance

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the pilots and operator of VH-XUM
• the master and manager of Star Coral
• the ship’s flag State administration, The Bahamas
• the helicopter manufacturer, Leonardo Helicopters
• Agenzia Nazionale per la Sicurezza del Volo (ANSV)
• Civil Aviation Safety Authority
• Australian Maritime Safety Authority 

Submissions were received from:

• the pilots of VH-XUM
• the ship’s flag State administration, The Bahamas
• the helicopter manufacturer, Leonardo Helicopters
• Agenzia Nazionale per la Sicurezza del Volo (ANSV)

The submissions were reviewed and, where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2025  Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the Australian Transport Safety Bureau.  Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

Investigation summary

What happened

On 16 November 2024, an amateur-built experimental certificate Morgan Cougar Mk 1 aircraft, registered VH-LDV, with a pilot and 2 passengers on board, departed from West Sale Airport, Victoria for a local area flight. The aircraft collided with terrain in a paddock it was orbiting around, about 19 km north-north-west of West Sale Airport, 17 minutes after departure. The aircraft was destroyed, and the 3 occupants were fatally injured.

The pilot was operating a VH-registered aircraft with a Recreational Pilot Licence (RPL), issued by CASA in recognition of the pilot holding a Recreational Pilot Certificate (RPC), issued by Recreational Aviation Australia (RAAus). 

What the ATSB found

The aircraft entered an accelerated aerodynamic stall while in a steep turn at a low speed and height from which it was too low to recover (about 220 ft above ground level). The pilot had a reported history of conducting steep turns at low heights, and on occasions at low speeds, and had low flying hours in the aircraft and no transition training. Therefore, it was likely that the pilot was not aware of the stall characteristics of the aircraft and that it might depart controlled flight in an abrupt and unexpected manner. 

The pilot’s history also included several counselling sessions they had received from members of the local aviation community in response to risky flying activities. However, no official reports were submitted to authorities and therefore no follow-up action was ever initiated.

A review of the pilot’s examination history revealed several errors about aerodynamic stalling in exams conducted during 2024 and it was concluded that the pilot likely had inadequate knowledge of the relationship between angle of bank, load factor and stall speed. Additionally, the investigation found several instances of irregular practices in training and exams at the Adventure Flight Training (AFT) school, which included the pilot’s exams, and concluded that those management practices likely contributed to the pilot’s inadequate knowledge.

RAAus administered the examination system, and it was found to have inadequate controls to mitigate the practices at AFT. When RAAus uncovered the problems at AFT in 2024, they issued a safety related suspension (SRS) notice against the chief flying instructor of AFT, which resulted in the cessation of operations in August 2024. 

After the accident, RAAus issued another SRS against the AFT graduates for potential knowledge deficiencies. However, when CASA were advised of this action, they did not follow-up to verify if any of those graduates also held a CASA licence granted based on holding an RAAus RPC which had been suspended. It was subsequently found that 2 members held a CASA-issued licence, granted based on their suspended RPCs.

Furthermore, the accident aircraft was found to have design deficiencies, which contributed to the severity of the occupants’ injuries. They included a lack of energy attenuation in the landing gear and seating, and the installation of a fuel tank between the engine and instrument panel that ruptured and caused the post-crash fire. In addition, it was likely that car seatbelts were fitted and the front seatbelts failed in the accident, which resulted in the front seat occupants being ejected from their seats. 

Finally, it was found that the CASA advisory circular for amateur-built experimental certificate aircraft provided recommendations to address some aspects of aircraft crashworthiness, which included seatbelts. However, it did not address energy attenuation or fuel tank installation. In addition, while it provided safety recommendations for pilots conducting flight testing, it did not recommend transition training for new owners of these aircraft.   

What has been done as a result

RAAus commenced a digital systems redevelopment project with scoping of user requirements completed in 2023, which includes their learning management system. This incorporates the implementation of an online exam system. RAAus are also progressing the re-drafting of several key documents in their Exposition, which includes updates to the following:

• flight operations manual to contain greater clarity around the conduct of RAAus examinations
• occurrence and complaints handling manual to include a description of the process for handling a safety related suspension for an individual if their membership has lapsed
• syllabus of flight training to include further development of the stalling element of the syllabus. 

CASA has implemented a more robust process to ensure that all reports received that relate to suspension, variation or cancellation of authorisations issued by an approved self‑administering organisation will include a review of CASA records to determine if the reported individual also holds a ‘same-in-substance’ CASA-issued authorisation. If so, the holder’s qualifications will be subject to review through the CASA Coordinated Enforcement Process.  

Safety message

The investigation revealed a trend in risky flying behaviour by the accident pilot, which was likely compounded by inadequate knowledge from a flight training school that had developed irregular practices in the delivery of training and had inadequate supervision. While many people knew of the pilot’s risky flying behaviour and had attempted to counsel them, there was no evidence that any of the incidents were reported to authorities, and the counselling efforts were ultimately unsuccessful. 

The ATSB has previously advocated for witnesses, particularly those within the aviation industry, to report any concerns regarding unsafe behaviours through mechanisms such as confidential reporting systems (see AO-2019-027). The ATSB re-iterates this previous safety message.

CASA has published recommended guidance for amateur-built experimental certificate aircraft. While this publication is directed at those who design, build and flight test these aircraft, the safety precautions should be read by new owners and considered equally applicable to them.

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns is reducing the severity of injuries in accidents involving small aircraft. In this accident the lack of energy attenuation and location of the fuel tank in the design of the aircraft and the likely fitment of car seatbelts all increased the risk to occupants in the event of a ground collision. 

Summary video

The occurrence

At 1730 local time on 16 November 2024, an amateur-built Morgan Cougar Mk 1 aircraft, registered VH-LDV, with a pilot and 2 passengers on board, departed from West Sale Airport, Victoria for a local area flight. The pilot was seated in the front left seat, and the passengers were seated in the front and rear right seats. A review of Airservices Australia automatic dependent surveillance-broadcast (ADS-B) data identified that the aircraft conducted a left turn on departure and tracked 15 km north of West Sale Airport to the town of Maffra, where they arrived overhead at about 1736 (Figure 1).

Figure 1: Accident flightpath with key timings and locations

Sources: Airservices Australia and Google Earth, annotated by the ATSB

The aircraft made a series of turns overhead the town of Maffra for about 4 minutes. At 1740, the aircraft departed from overhead Maffra and tracked about 11 km west towards Tinamba West. The aircraft conducted a right-hand turn overhead a property at Tinamba West, which belonged to relatives of the aircraft occupants, before commencing a series of left-hand turns (orbits) around a point about 1 km to the south-east of the property over open paddocks (Figure 2). 

On the second orbit, the aircraft made a low pass along the Macalister River, adjacent to where several witnesses, which included 2 adults, were located. The 2 adults later stated that they had witnessed the aircraft conduct 2 orbits past their location before the accident. They reported the second pass along the river was lower than the first, such that they could both see the occupant in the rear seat, and that the aircraft sounded normal.

Figure 2: Orbits and the location of witnesses

Sources: Airservices Australia and Google Earth, annotated by the ATSB

A closed-circuit television (CCTV) camera, located about 700 m north-north-east of the accident site, captured the aircraft entering a left turn towards the camera on its third orbit (Figure 3 [1]). During the turn the angle of bank increased to a steep turn attitude (Figure 3 [2]) before the nose of the aircraft pitched down and the aircraft descended in the left turn behind trees (Figure 3 [3]). 

Figure 3: CCTV footage of final turn

Images subject to visual distortion (fisheye lens effect). Source: Victoria Police, annotated by the ATSB

One of the witnesses reported that, as the aircraft approached them for a third pass, it did a hard left turn and then appeared to be falling and not gliding towards the ground, as though it did not have enough speed. They reported that the wings levelled after the turn and it landed very hard on its belly and immediately caught fire. The second witness saw it bank hard left and fall out of the sky but did not see the collision. The 3 occupants were fatally injured, and the aircraft was destroyed.

Context

Accident site and wreckage

Overview

The aircraft impacted flat and open terrain at an elevation of about 130 ft and produced a ground scar on a track of 315° T (Figure 4). The length of the wreckage trail was 30.3 m from the first ground scar to the propeller spinner, with the fuselage resting on a heading of 303° T. Impact analysis indicated the aircraft struck the ground in a slight left wing low and close to level pitch attitude, which was consistent with the witness report of the collision.

Figure 4: Accident site

Source: ATSB

There was a delta-shaped fuel spray and debris pattern along the wreckage trail. A fuel‑fed fire occurred after the ground impact, however, most of the fire damage to the aircraft was confined to the fuselage within the area bounded by the firewall,[1] aft bulkhead (behind rear seats) and the inboard sections of the wings (Figure 5). The engine and propeller were also affected by the post‑impact fire, but to a lesser extent than the fuselage. The wings and tailplane (except the rudder) remained attached to the fuselage. The rudder was found in the wreckage trail. 

Figure 5: Fire damage to the aircraft

Source: ATSB

The engine remained attached to the firewall, which had separated from the fuselage, and the 3-bladed propeller hub was attached to the engine. There was considerable disruption between the engine and airframe. One substantially fire-damaged carbon fibre propeller blade was attached to the hub and the other 2 propeller blades, which were not fire‑affected, had separated at their roots and were found fragmented within the debris field.

Aircraft inspection

Engine and propeller

The 2 witnesses to the accident sequence provided different accounts of the noise of the aircraft just prior to the collision. One reported that the aircraft sounded normal before the final turn and then went quiet, whereas the other witness reported no change in the sound of the aircraft during the accident sequence. 

The intake manifolds, carburettors, drive belts, oil hoses, and fuel lines were heavily damaged by the post-impact fire. The left carburettor was damaged beyond assessment, and the right carburettor was found with the throttle valve in the idle position. However, the carburettor throttle valve is spring loaded to idle, so the as-found position was not considered a reliable indicator of its position in flight.

The number 1 cylinder head was removed for inspection and was found to be lubricated and did not exhibit any signs of distress. The other cylinders could not be accessed due to impact damage. The engine oil filter and oil sump magnetic plug were inspected, and no metallic debris was identified.

The turbocharger compressor scroll was found separated from the turbocharger and directly below the turbocharger assembly. The scroll exhibited an overstress failure, with fracture surfaces but no scoring. Several turbocharger compressor vanes exhibited bending in the opposite direction of rotation, which indicated the compressor was running at impact (Figure 6).

Figure 6: Rearward bending of turbocharger compressor vanes

Source: ATSB

The propeller hub was secured to the engine output flange by 6 bolts and concentric locating pins. The hub was removed for inspection and very slight ovalisation of all 6 of the locating pins’ hub-side holes in the direction of rotation was noted. 

Two of the propeller blades fractured at the blade root and separated from the hub, leaving the propeller root sections still clamped in the hub. The carbon fibre remnants on the root sections indicated tearing and separation of the blades in the opposite direction to rotation. 

One of the propeller blade root hubs was relatively unbent and the following blade root hub (in the direction of rotation) exhibited rearward bending. This suggested a loss of propeller energy between consecutive blade ground strikes and the possibility that the first blade to separate was being driven by engine power.

The use of non-metallic propeller blades increased the uncertainty in the engine power assessment. However, in combination with the turbocharger compressor damage it was concluded that the engine was operating at impact, but the power level could not be determined. 

Flight controls

Primary aircraft flight controls were of the direct acting cable, pushrod, and bellcrank type with a dual yoke control installed for elevator and aileron control. The wing flaps were electrically powered and found in the retracted position. The flaps could not be tested due to damage.

Rudder, elevator, and aileron controls were free to move about their full range. Several control cables were found severed and were inspected for signs of pre-impact failure. No wear, bird-caging, fretting, or other indications of damage were noted on the cables, and it was concluded that all these cables failed from overstress during the ground collision.

The rudder separated from the vertical stabiliser and was found in the wreckage trail. The mounting hardware was found, and the fracture surfaces of the flight control attachment points were consistent with an overstress failure.

While ATSB investigators were handling the yoke controls for inspection and photography, the chainring, which was part of the aileron control, separated under gravity from its bearings and support frame (Figure 7). However, given that they were not found separated, and that the aircraft attitude was recovered towards wings-level before the collision, it was concluded that the controls did not separate in-flight. The chainring and bearings were retained for further examination at the ATSB technical facility and details of that examination are provided in Appendix A – Examination of the flight controls.

Figure 7: Chainring separation from bearings and support frame

Source: ATSB

Fuel system

The aircraft fuel system consisted of a 55 L fiberglass tank in each wing, located aft of the main spar, and a 90 L fibreglass main tank between the instrument panel and the firewall. Fuel could be transferred from the wing tanks to the main tank via an electric transfer pump. The engine feed was from the main tank, via a fuel filter and 1 of 2 electric pumps.

The wing fuel tanks were found empty and relatively undamaged. The main tank was completely consumed by the impact and fire, along with significant parts of the surrounding fuselage. This was consistent with the flight fuel carried in the main tank.

Undercarriage

The undercarriage was a fixed tricycle gear, with a single-piece fibreglass strut supporting both main wheels, and a castering, spring lever nose wheel. The main and nose gear were found in the wreckage trail and their separation from the airframe was consistent with multiple overstress failures of the attachments at impact. The main gear assembly exhibited no evidence of permanent deformation or absorption of energy. 

Seats and restraints

The aircraft was designed and built with 2 front seats and a 2-place rear bench-seat arrangement. The front seats were found in the wreckage, and their rear mountings were attached to the fuselage seat frame aluminium angle cross-member. The steel bolts used to mount the rear of the seats to the aluminium angle were present and fastened. The forward steel cross-member for the front seats was bowed forward (Figure 8). The right seat pan was retained by the seat back and appeared to have collapsed onto the main wing spar,[2] located underneath the front seats. The left front seat pan had separated from its seat back and was found in front of the seat frame forward cross-member.

Figure 8: Aircraft seat frame, wing spar and seats

Source: ATSB

Both front seatbelt latch plates were found separated from their buckles and their associated harnesses were destroyed by the fire (Figure 9). The rear seats and seatbelts were destroyed by the post‑impact fire. However, the seatbelt latch plate for the rear seat occupant was found in its buckle.

Figure 9: Aircraft seatbelt latch plates

Source: ATSB

Instruments and avionics

The aircraft was fitted with:

• a Dynon Skyview SV-D1000 avionics unit, which provided a primary flight display with a navigation display and engine instruments display
• a 2-channel autopilot system
• analogue airspeed, oil pressure, altimeter, turn/slip and vertical speed instruments.

The instrument panel and instruments were found together in the wreckage, forward of the front seats and behind the engine firewall. All instruments and the panel were destroyed by the impact and fire. However, the Dynon unit was retained by the ATSB for examination (see the section titled Flight path analysis).

Meteorological information

The Bureau of Meteorology provided 30-minute METAR[3] recordings for the East Sale Airport, located about 30 km south-east of the accident site. At 1730, the temperature was 26°C and the wind was 17 kt from 090° T. The visibility was greater than 10 km and no cloud was detected. Similar conditions were recorded at 1800. A local weather station about 4 km north of the accident site recorded the weather data at 5-minute intervals. Table 1 presents the temperature, mean wind and wind gust data recorded at 1745 and 1750 by the local weather station.

Table 1: Local weather station recordings

Flight path analysis

The aircraft was fitted with a Dynon Skyview SV-D1000 avionics unit, with the capability to record various flight path parameters. The unit was recovered from the accident site and examined at the ATSB facilities. The memory chip was recovered from the internal memory unit and read. However, due to the extensive thermal exposure beyond the specifications of the chip, the data was corrupted and not usable.

Airservices Australia ADS-B data was obtained for the flight path analysis. The data included altitude in 25 ft increments and groundspeed with timings, which were combined with the CCTV camera footage for flight path analysis. A mean wind speed of 6 kt and wind gust speed of 12.8 kt from 124° T were used to calculate a range of estimated calibrated airspeeds (CAS) for each data point.

A trend over the last 3 minutes was noted with the aircraft generally descending from a recorded altitude of 850 ft above mean sea level (AMSL) to 275 ft AMSL, with a low pass at 97 ft above ground level (AGL) during the second left orbit overhead the Macalister River. The groundspeed varied over the last 3 minutes from 103 kt to 71 kt, with a gradual and almost continuous reduction in speed below that recorded during the previous orbit speeds over the last 30 seconds of the flight.

The final turn started at 1746:52 at 64 kt (67–74 kt CAS) and 269 ft AGL. The nose drop observed in the CCTV footage during the final turn, followed by a rapid descent, was indicative of an aerodynamic stall[4] in a steep turn. The stall likely occurred at 1746:59 at 56 kt (59–65 kt CAS) and 221 ft AGL. After the stall there was an abrupt reduction in altitude and increase in speed, consistent with initiation of a stall recovery (Figure 10).

Figure 10: Plot of ADS-B data and CAS calculations

Source: ATSB

The final turn was of a tighter radius than the previous orbits and analysis of the radius of this turn indicated it was consistent with a turn to align with the Macalister River and would have required an average angle of bank of 45° in a steady coordinated turn. The turn radius appeared to reduce during the turn at a relatively constant speed, which would have required an increase in the angle of bank and load factor. For about the last minute of flight, the aircraft was operating below a height of 500 ft, which was the minimum height applicable to this portion of the flight, as prescribed in Civil Aviation Safety Regulation (CASR) 91.267. Further description of each orbit is provided in Appendix B – Flight path description.

Aircraft information

General information

The aircraft was an amateur-built Morgan Cougar Mk 1, registered VH-LDV, issued with a special certificate of airworthiness under the designation: experimental certificate. It was a 4-seat, piston-engine aircraft with a maximum take-off weight of 800 kg. The aircraft was fitted with a Rotax 912 ULS 4-cylinder turbocharged engine and 3-bladed composite (carbon fibre) propeller. The aircraft’s builder sold it to a syndicate of 3 pilots, which included the accident pilot, on 5 November 2024, with its manufacture date recorded as 2013 and with 136.9 airframe hours.

The aircraft build started in May 2013 and the experimental certificate for Phase 1 flight testing was issued by a Civil Aviation Safety Authority (CASA) delegate in December 2015. The experimental certificate for Phase 2, completion of the test flying phase, was issued by the same CASA delegate in April 2017. 

Amateur-built experimental aircraft

According to the CASA advisory circular (AC) 21-10 v4.3: Experimental certificates, an experimental certificate may be issued for the purpose of operating amateur-built aircraft, and it does not attest to the airworthiness of the aircraft. CASA AC 21.4(2): Amateur-built experimental aircraft – certification (published in 2000) stated:

An amateur-built aircraft is an aircraft, the major portion of which has been fabricated and assembled by a person or persons who undertook the construction project solely for their own education or recreation. 

Amateur builders should call upon persons having experience with aircraft construction techniques…to inspect particular components…prior to closure and to conduct other inspections as necessary.

The AC required an authorised person, or CASA, to only inspect the aircraft once prior to the initial test flight and the inspection should establish that:

• the aircraft is registered and marked in accordance with the requirements

• the aircraft meets the major portion rule

• the weight and balance data is available and the aircraft has been correctly weighed

• the engine(s) and flight controls operate properly

• the pitot static system and associated instruments operate properly.

• Note: The person carrying out the inspection is not responsible for the integrity of the design or construction of the amateur-built experimental aircraft, nor for the identification of any structural design or construction deficiencies — responsibility for the design, construction and integrity of the aircraft rests with the amateur builder. 

In accordance with CASA AC 21.4(2), the builder maintained a build-log that detailed the progressive build of the aircraft with photographs and notes. The builder consulted with the designer during the initial build and with both the designer and the CASA delegate for subsequent modifications. The designer of the aircraft was deceased prior to the accident. 

Weight and balance

The maximum take-off weight published in the aircraft logbook was 800 kg and the centre of gravity limits were between 2,263 mm and 2,537 mm aft of the datum. The aircraft was reweighed 2 days prior to the accident, which involved transferring all fuel remaining in the wing tanks into the main tank. The transfer process resulted in empty wing tanks and a full main tank.

The weight and balance for start-up and at the time of the accident were calculated and found to be within the published limits. 

Builder modifications to the design

The aircraft builder reported to the ATSB that they made several modifications to the original design, consulting with the CASA delegate and designer about the changes. They reported that under the original design, aileron and elevator control was via a stick, with a linear relationship between stick and control surface movement across the full range. However, the stick control required large inputs for small movements of the control surfaces, felt sloppy and was designed with components bolted to the floor in a manner that exposed them to interference from the occupants. 

After a taxiing accident in 2019, the builder incorporated modifications, which included a new engine (Rotax) and propeller, yoke controls and roller bearings to eliminate lateral movement (play) in the horizontal stabilator control tube. The builder noted improved climb and cruise performance after the modifications, but reported the greatest improvement was in flight handling. 

Following the modifications, the roll, pitch and yaw motions were described as ‘smooth, linear and predictable… There was no slop in the control system and this resulted in the aircraft being responsive without being twitchy.’ The autopilot actuators provided additional resistance and a heavier feel to the original design. The builder reported no noticeable changes to the stall speed or aircraft reaction during a stall after these modifications but recovery from a stall was reported to be quicker than previous. 

Aircraft stall warning and characteristics

Stall warning

While not published in the pilot operating handbook (POH), the aircraft was fitted with a stall warning system incorporated into the Dynon avionics unit. The documentation for the unit stated that it provided an audio alert as the angle of attack increased, which started as an intermittent tone and increased in frequency as the angle of attack increased, until it became a continuous tone at the critical angle of attack.[5]

There were 3 options in the settings for how early the intermittent tone activated. The ATSB could not determine what was set or if a calibration flight was conducted. The builder reported that they believed it was factory set and one of the new owners reported they believed there was an angle of attack indicator but no audible stall warning. They further stated that they had not conducted any of their own verification/calibration flights before the accident.

Stall characteristics

The stall characteristics were described in the POH as having about a 10 kt buffet warning before a slow nose drop at the stall until flying speed was regained. The POH’s published ‘straight and level’ clean indicated stall speed was 37 kt. However, after construction, the aircraft was subject to 40 hours of restricted flying operations under Phase 1 of its experimental certificate, which included stall testing. The results from Phase 1 testing were recorded in the aircraft logbook, which indicated the stall speed was found to be 38 kt. 

The builder described the aircraft handling characteristics approaching the straight and level clean stall as ‘a mush’ with no sudden nose‑down pitching moment. However, they reported that during a 30° angle of bank left turn, the aircraft started to stall at about 42 kt and then suddenly pitched nose-down with a left yaw. The aircraft was quickly recovered but the builder was reportedly surprised by the different response to a stall in a turn to what was experienced in straight and level flight and hypothesised that a greater angle of bank might exacerbate the response.

The following table presents the indicated stall speeds and load factors in level coordinated turns from wings level to 75° angle of bank and up to a load factor[6] of 3.86, noting the published manoeuvring limit for the aircraft was 4G. The manoeuvring stall speed was calculated by multiplying the 1G stall speed by the square root of the load factor.

Table 2: Calculated stall speeds for increasing angle of bank and load factor

The builder recalled discussing various types of stalls, including accelerated stalls, with the aircraft designer. However, the designer recommended against the builder testing these characteristics unless accompanied by either the designer or an experienced instructor. The builder did not conduct any stall testing additional to that detailed above.

Stall testing for amateur-built aircraft

In AC 21.4(2), CASA ‘strongly urged’ builders to ‘make detailed reference to the U.S. FAA [Federal Aviation Administration] Advisory Circular AC 90-89, “Amateur-Built Aircraft Flight Testing Handbook”, prior to their flight programs commencing, and follow the guidance provided.’ In accordance with the FAA AC, for straight and level stall testing, the aircraft should be slowed towards the expected stall speed at 1 kt per second and the stall warning should occur about 5 kt before the stall. 

The FAA AC stated that a sharp wing drop during stall testing could be regarded as the onset of spin autorotation, and the recommended corrective action is reducing power, full opposite rudder, and lowering the nose to the horizon or below. The guidance for flight testing of accelerated stalls provided the following description:

An accelerated stall is not a stall reached after a rapid deceleration. It is an in-flight stall at more than 1 G, similar to what is experienced in a steep turn or a pull up.

The accelerated stall is based on a closure rate between the aircraft speed and stall speed. Standards for type certified aircraft have historically[7] used a closure rate of 3‍–‍5 kt per second for testing accelerated stall characteristics or required a minimum load factor for the test conditions (Gratton, 2015). 

A turning manoeuvre is often used for the accelerated stall testing, which can affect the aircraft response. According to Gratton (2015), low wing aircraft tend to roll into the turn during a turning stall and high wing aircraft tend to roll out of the turn. Consequently, certification authorities have historically placed roll limits on the acceptable response of an aircraft during a turning or accelerated stall (Gratton, 2015). Therefore, accelerated stall flight testing may not be recommended for an amateur-built aircraft and the notes within the accelerated stall section of the FAA AC contained the following advice:

Do not attempt this or any other extreme maneuver unless the designer or kit manufacturer has performed similar tests on a prototype aircraft identical to the amateur-builder’s aircraft.

Of note, the reference from Gratton (2015) that low wing aircraft tend to roll into the turn during a turning stall, will, in combination with a nose down pitch, produce a nose low unusual attitude to the pilot. While the correct recovery technique from a conventional stall is to apply power as soon as the wings are unstalled, the standard recovery technique from a nose low unusual attitude is to close the throttle, roll wings level and then pull up (CASA, 2007).

Transition training

Purchase of the aircraft

The builder sold the aircraft due to medical issues that made it difficult for them to inspect and operate the aircraft and inhibited their ability to egress from the aircraft in an emergency. Consequently, the builder did not accompany any potential buyers on their trial flights. The inspections and trial flights of the aircraft occurred at Whyalla Airport, South Australia, and the syndicate that purchased the aircraft were the second interested buyers.

The builder reported that the first interested buyer had about 800 hours experience on slower aircraft, which included experimental kit-built aircraft. The buyer conducted a trial flight accompanied by a more experienced pilot who advised them against the purchase due to the performance difference from their previous aircraft. The accompanying pilot reported to the builder that the buyer was used to flying 80 kt aircraft, not 130 kt aircraft.

The syndicate that purchased the aircraft consisted of a recreational pilot certificate (RPC) holder and 2 Recreational Aviation Australia (RAAus) instructors. The instructors each held a CASA-issued recreational pilot licence (RPL) with navigation endorsement, and one of them was the accident pilot. They arrived together at Whyalla Airport in another light aircraft as the second prospective buyers. 

The syndicate conducted several trial flights at Whyalla, and the builder briefed them on the aircraft logbook and the POH but could not recall the specific details of what was covered. The builder believed the syndicate members were going to study the POH the night before their departure from Whyalla and the builder made themselves available the following day to answer any questions but could not recall if any were asked. The syndicate members signed the sale agreement on 5 November 2024 and departed from Whyalla with the aircraft on 6 November. 

The builder had no recollection of discussing the aircraft’s banked stall characteristics with them and had never received such a brief themselves in the past when introduced to a new aircraft. They did not advise the syndicate to seek transition training or recommend aerial work exercises as part of their familiarisation process. The builder was aware that 2 of the syndicate members held instructor qualifications with RAAus in addition to CASA licences. Therefore, the builder (who was not an instructor themself) did not think it was necessary to advise them about flight training matters.

One of the syndicate members was concerned about the aircraft’s centre of gravity with rear seat passengers and they agreed to have it reweighed before conducting any of their own verification flights. This was done at West Sale Airport on 14 November 2024, and no significant changes were recorded by the weight and balance organisation.

As the aircraft was in the single-engine class rating of less than 1,500 kg, the syndicate’s RPL-qualified pilots were able to fly the aircraft without additional flying training or qualifications. The ADS-B data history for the aircraft revealed about 7.7 hours were flown by the syndicate from 4 November 2024 until the accident flight, which included 4.5 hours of ferry flights from Whyalla to Moama, New South Wales, and from Moama to West Sale. There were also several check flights associated with rectifying a blocked fuel strainer. While the accident pilot had received dual transition training for other aircraft, which included the Bristell and Pitts Special, this was not undertaken on the accident aircraft.

One of the syndicate members reported that they didn’t think the pilot had the opportunity to do any aerial work exercises in the aircraft before the accident and they suspected that the pilot may not have appreciated the heavier aircraft, in which they had low flying hours. The other syndicate member reported that the pilot had limited flying experience in the aircraft and suspected that the pilot did not understand the risks of what they were doing with respect to steep turns, load factor and the associated effect on stall speed.

CASA flight testing and training advice

CASA AC 21.4(2) included recommended safety precautions for the flight-testing phase, emphasising that:

• a graduated process of familiarisation should be followed, starting with the ground handling characteristics of the aircraft before attempting flight operations
• emergency equipment and personnel should be available before the first flight
• ‘Violent or aerobatic manoeuvres should not be attempted until sufficient flight experience has been gained to establish that the aircraft is satisfactorily controllable throughout its normal range of speeds and manoeuvres.’

The minimum qualifications required for the Phase 1 flight testing was a CASA-issued private pilot licence (PPL) with the appropriate endorsements.

CASA AC 21.4(2) also stated that ‘Flight training will be permitted under certain circumstances, i.e. type endorsement training and training given in the aircraft to its owner.’ A separate section addressed the maintenance aspects for new owners, which prohibited them from certifying for maintenance, and that it must be certified by a Licenced Aircraft Maintenance Engineer (LAME) when no longer owned by the builder. However, there was no recommendation for new owners to seek transition training or for designers or builders to recommend buyers conduct transition training.

ATSB aviation research investigation

The ATSB aviation research report 

Amateur-built aircraft Part 2: Analysis of accidents involving VH-registered non-factory-built aeroplanes 1988-2010, was published in 2013. It included findings related to the accident and injury rates (with implications for the crashworthiness of these aircraft) and the experience of pilots involved in these accidents, as follows:

Amateur-built aircraft had an accident rate three times higher than comparable factory-built certified aircraft conducting similar flight operations between 1988 and 2010. The fatal and serious injury accident rate was over five times higher in amateur-built aircraft, in particular due to relatively more serious injury accidents. 

The pilots of amateur-built aircraft involved in accidents were significantly more experienced overall than factory-built aircraft accident pilots. However, they were significantly less experienced on the aircraft type that they were flying at the time of the accident.

A quarter of accidents were from loss of aircraft control.

The safety action section of the report included initiatives from the Sport Aircraft Association of Australia (SAAA), as follows:

Working with the Civil Aviation Safety Authority (CASA) to provide a legal framework for better training in amateur-built aircraft.

Working with CASA to allow a legal framework for suitably qualified pilots to give instruction in amateur-built aircraft both for the aeroplane flight review (AFR) and transition training for pilots (post-phase one).

The SAAA subsequently produced a Flight Training and Safety Manual supported by their Flight Safety Advisor program. However, a pilot operating an experimental aircraft needed to be a member of SAAA to access these resources.

Federal Aviation Administration advisory circular

In 2012, the United States National Transportation Safety Board published a safety study on The Safety of Experimental Amateur-Built Aircraft (NTSB/SS-12/01). Their study found that pilots who did not seek training were over‑represented in accidents, and that accidents involving loss of control could be reduced with transition training. This led to a recommendation for the FAA to develop resources for transition training and encourage builders and new owners to complete the training.

In 2015, the FAA published AC 90-109(A) Transition to unfamiliar aircraft. The purpose of the FAA AC was ‘to help plan the transition to any unfamiliar fixed-wing airplanes, including type-certificated (TC) and/or experimental airplanes.’ The AC stated that ‘accidents resulting from loss of aircraft control or situational awareness frequently result from pilot unpreparedness for challenges presented by the aircraft’ and provided recommendations for training experience based on aircraft performance and handling characteristics. It contained an extensive section on stall characteristics, which included the following points:

There are no rules for stall behavior with experimental airplanes.

Some experimental airplanes can be flown in a carefree manner with the stick all the way back, while others can depart controlled flight dramatically without any perceptible warning.

Since amateur-built airplanes are built by individuals, there can be a wide variation in the stall behavior of identical models.

Receive training in your airplane on stall avoidance and recovery from a qualified instructor, preferably with recent experience in the make and model.

Periodically practice stall avoidance, entry, and recovery at a safe altitude after you have received enough instruction to feel comfortable. Stall recognition and recovery should not be self-taught. Your first experience should not come from an inadvertent stall that catches you by surprise.

The appendices of the FAA AC provided a list of families of aircraft, based on their characteristics, with examples of experimental aircraft within each family. The accident aircraft was described to the ATSB as being responsive by the builder and very responsive by one of the syndicate members. Appendix 3 of the FAA AC was for aircraft with rapid flight control response, and it included the following information:

There are many more experimental airplanes that may look more like type-certificated (TC) airplanes, but they actually have light control forces and/or very quick maneuvering response. The hazard of light forces and rapid response is that without some level of training, the pilot may over-control the airplane.

Best Training. The best training is accomplished in the specific airplane the pilot intends to fly with a well-qualified instructor who has recent experience in the specific make and model.

In this case, the accident pilot had conducted transition training on the Pitts Special aircraft with an instructor who also had experience with the Morgan Cougar Mk 1 aircraft, though not the accident aircraft. The instructor’s experience with the Morgan Cougar included flying them and modifying them to improve their handling qualities. This offered the accident pilot an opportunity to undertake transition training for the Morgan Cougar Mk 1 that would have been consistent with the ‘best training’ model recommended in FAA AC 90-109(A).

Crashworthiness and survivability

Occupant positions and injuries

The seating configuration during the flight was the pilot in the front left seat, a passenger in the front right seat and a second passenger in the rear right seat. A full autopsy was conducted on the pilot, and a computed tomography scan and external examination was conducted on the 2 passengers at the Victorian Institute of Forensic Medicine. Toxicology analysis of blood was conducted for all occupants.

The examinations for all occupants revealed extensive non-survivable blunt force trauma injuries to the head, chest and lumbar spine. Examination of the pilot indicated that they were deceased prior to the fire. Toxicology results found no ethanol, common drugs or poisons, and carboxyhaemoglobin (an indicator of carbon monoxide exposure) was not detected.

CREEP methodology

The CREEP methodology used for analysing the crashworthiness and survivability of aircraft accidents is based on:

• Container – maintain a liveable volume
• Restraint – retain the occupants in their seats and the seats to the airframe
• Energy attenuation – minimise the transmission of forces to the occupants
• Environment (local) – minimise the lethality of the cockpit and cabin to flailing injuries
• Post-crash factors – egress and minimise the risk of drowning, fire and fumes.

Container

The occupied cabin area of the aircraft was visible, though significantly damaged from fire and the underside compromised from the ground impact. The outline of the cabin was discernible and displayed dynamic deformation of the structure supporting the front seats and the main spar located underneath the front seats, which is discussed further in the following sections.

Restraint

The pilot and front right seat passenger were ejected from their seats during the accident, and their seatbelt latch plates were found separated from their respective buckles. The rear seat occupant appeared to have remained restrained and was found in the rear right seat location with their seatbelt latch plate attached to the buckle. The pilot was seen wearing a 3-point harness in videos taken during the accident flight. Therefore, it was considered very likely that all 3 occupants were wearing their seatbelts.

According to the build log, the front seats were from a Toyota Prado motor vehicle, and the seatbelts were connected to the seat mounts and airframe with their shoulder straps extending from centre to outboard, where the buckles were located. Regarding seatbelts, AC 21-4(2) para 7.3 stated:

It is strongly recommended that US [United States] FAA [Federal Aviation Administration] Technical Standard Order (TSO) approved or equivalent seat belts be installed along with approved shoulder harnesses. 

According to the build log, the builder conducted load testing of the seat belts in accordance with FAA AC 23-4 Static strength substantiation of attachment points for occupant restraint system installations. This involved the application of a simulated 4G load (400 kg) downwards and forwards to test the seats and seatbelt attachments, which they passed. The TSO specified the minimum performance standards were those in the Society of Automotive Engineers Aerospace Standard AS 8043 (1986), which included the following information:

Pelvic Restraint: A torso restraint system shall provide pelvic restraint whether or not an upper torso restraint is used. Pelvic restraint shall not incorporate emergency locking retractors (inertia reels).

Release: A torso restraint system shall be provided with a single buckle having a single motion release which is readily accessible to the occupant to permit easy and rapid egress by the occupant from the assembly. The buckle release mechanism shall be designed to minimize the possibility of inadvertent release.

A review of car and aircraft seatbelt images revealed a general difference between the design. Car seatbelt latch plates are threaded through the strap connected from the shoulder to the pelvic anchor point on the shoulder strap side. The inertia reel applies the tension, and emergency locking under acceleration, when the latch plate is inserted in the buckle on the opposite side. Therefore, the pelvic restraint (lap belt) incorporates an inertia reel because it is part of the upper torso restraint mechanism. 

The aircraft builder confirmed that this was the design of the front seatbelts fitted to the aircraft and that they were probably car seatbelts. The inertia reel was located at the shoulder anchor point on the inboard side of the seats and the shoulder strap extended down to the inboard pelvic anchor point with the latch plate threaded through the strap. The inertia reels at the shoulder anchor points provided the tension and emergency locking under acceleration for the front seat occupants.  

Seatbelts can fail due to overload, which is why strength tests are conducted, and they can also fail to perform a required function, such as restrain the occupant during a collision. Roberts et al. (2007) described 3 known failure modes associated with car seatbelt design as follows:

• inadvertent unlatching when the buckle is unlatched due to occupant flailing contact with the release button during an accident
• false latching when the buckle fails to engage completely, but gives the user the impression that it is properly fastened due to its partial engagement
• inertial unlatching when the buckle unlatches due to inertial forces resulting from impacts and the associated impulse accelerations during planar collisions and rollovers, which is an example of a component failing to perform a required action.

Energy attenuation

All 3 occupants had fractures of the lumbar spine and the 2 front seat occupants both had crush fractures of the fifth lumbar (L5) vertebra. According to Shanahan (2004) light fixed‑wing aircraft provide little crushable structure to attenuate collision forces. However, 2 areas where energy attenuation can be incorporated into the design are the landing gear and seating. The main landing gear for the Morgan Cougar aircraft was a rigid single-piece structure with the wheel axles attached to the structure. It separated on impact and there were no oleos for energy attenuation incorporated into the design. 

The rear seats were upholstered 4 mm plywood mounted to the cross-members. The front seats were car seats, which were attached to cross-members and had the main wing spar underneath them. The front right seat pan was found collapsed onto the wing spar and the left seat pan had separated and was found forward of the front seat frame structure. None of the seats incorporated any recognisable form of energy attenuation.

According to Stech and Payne (1969), the G-loading strength of the L5 vertebra for a 160 lb (72.6 kg) male is around 25G. The 25G limit was acknowledged by Shanahan (2004) with the following caveat:

However, poorly designed seats can produce spinal fracture in impacts as low as 8-10G. Typically, spinal fractures in low to moderate velocity crashes are caused by mounting seats above rigid panels or other non-frangible objects such as batteries and from mounting relatively rigid seats directly on bulkheads or over beams. In the first case, seats collapse onto unyielding objects causing the occupants to experience excessive vertical accelerations. In the latter case, rigid bulkheads or structural members transmit excessive forces from the ground directly to the seat occupants. 

According to Taylor and Moorcroft (2023) from the FAA Civil Aerospace Medical Institute, special energy attenuating seats are used to provide a controlled deceleration over a vertical stroking distance to keep aircraft crash loads within human tolerance. While there are many methods to achieve a controlled deceleration, some of the simplest and lightest methods include collapsible sheet metal boxes for the seat pan structure and/or the use of rate sensitive foams for the seat pan cushion.

CASA AC 21.4(2) para 7.3 recommended safety considerations for the design of the cockpit and seatbelts to reduce injuries to the pilot and passengers in the event of an accident. It also strongly recommended the use of FAA TSO seatbelts and shoulder harnesses. However, there was no recommendation for the designer or builder to consider energy attenuation for the occupants, specifically the energy attenuation of seating.

Environment (local)

The local environment was not considered to be a significant contributing factor in this accident due to the severity of the occupants’ spinal injuries (indicative of excessive vertical forces) and because the front seat occupants were ejected from their seats. In addition, CASA AC 21-4(2) para 7.3 recommended the ‘delethalization’ of the cockpit as follows:

The design of the cockpit or cabin of the aircraft should avoid, or provide for padding on, sharp corners or edges, protrusions, knobs and similar objects which may cause injury to the pilot or passengers in the event of an accident.

Post-crash factors

The aircraft was designed with a main fuel tank located between the engine firewall and the instrument panel. This made it susceptible to crushing forces in an impact and presented a risk of fuel spray onto the occupants and onto the engine as an ignition source, which occurred in the accident. The fire damage to the aircraft was centred on the cabin and engine area with die-back of the grass evident in a diamond pattern from the initial impact to the point of rest.

The builder modified the original design to incorporate wing fuel tanks in the design, located aft of the main wing spar. The modified wing tanks were not compromised by the collision. The importance of fuel tank location on post-crash survival was described in Johnson et al. (1980 and 1989) Aircraft Crash Survival Design Guide Volume V – Aircraft Postcrash Survival as follows:

The location of the flammable fluid-carrying tank in an aircraft is of considerable importance in minimizing the postcrash fire hazard from a tank installation. The location must be considered with respect to occupants, ignition sources, and probable impact areas.

Greater distance between occupants and fuel supply tends to increase escape time in the event of a fire because it reduces the likelihood of fuel entering the occupied area. Also, the tank should be kept away from probable ignition sources… Another important consideration is the location of tanks with respect to probable impact damage. Accident histories show repeated tank ruptures and consequent fires…, indicating the tank’s high degree of vulnerability to damage from surrounding structures.

As much aircraft structure as possible should be allowed to crush before the tanks themselves are exposed to direct contact with obstructions.

CASA AC 21.4(2) para 7.4 recommended reducing the risk of fire hazard, and the inclusion of a fireproof firewall between the engine compartment and the cabin. However, it did not recommend or advise on how to incorporate crashworthiness into the design of the fuel system.

Pilot information

Qualifications

The pilot held a:

• Recreational Pilot Licence (Aeroplane) (RPL-A), issued by CASA on 6 August 2024, with a single-engine aeroplane class rating and manual propeller pitch control endorsement
• Class 2 aviation medical certificate, issued in June 2024.

The RPL licence was granted in recognition of the pilot holding a recreational pilot certificate (RPC) with RAAus in accordance with Civil Aviation Safety Regulation (CASR) 61.480. In addition, the pilot held an RAAus-issued instructor rating and had accumulated 506.8 hours according to their last logbook entry, dated 7 August 2024. 

Flight training

Recreational aviation flight training

The pilot started flying training with RAAus at Adventure Flight Training (AFT) school in Moama, New South Wales, on 11 April 2022 for their RPC. The pilot passed their RPC flight test on 20 September 2022, and was endorsed with passenger carriage later in 2022, and with navigation and formation in 2023. All flight tests and endorsements were conducted and certified by the AFT chief flying instructor (CFI).[8] 

On 8 May 2023, the pilot started their RAAus instructor training at AFT and passed their instructor flight test at Bendigo, Victoria, on 7 July with an external testing officer. The pilot started delivering instructional flights at AFT on 16 July 2023.

On 19 December 2023, the pilot passed their senior instructor flight test with the AFT CFI and on 3 January 2024, the CFI endorsed the pilot’s logbook with the entry ‘meets the requirements for senior instructor rating iaw RAAus syllabus of flight.’ However, the pilot had not completed the theory exam requirement to be a senior instructor and their rating for senior instructor was not issued by RAAus.

General aviation flight training

The pilot’s logbook had entries for the following general aviation training flights in 2024:

• On 5 June, the pilot started dual flying training in the Pitts Special aerobatic biplane at Latrobe Valley and recorded 0.7 hours.
• On 6 June, the pilot successfully completed a flight review of 2.5 hours duration with a controlled airspace/aerodrome endorsement in a Cessna 152 (a flight review was required to exercise the privileges of a CASA RPL, which was issued in August).
• On 6 June, the pilot recorded a further 0.5 hours of dual flight training in the Pitts Special.
• On 1 July, the pilot recorded 3.1 hours of dual aerobatics training in the Pitts Special.

While the ATSB was informed that the pilot’s flying in the Pitts Special was for the purpose of an aerobatics endorsement, the flight training school (FTS) where the pilot conducted their RPL flight review did not have them enrolled for an aerobatics endorsement. In addition, CASA reported that they did not have an aerobatics endorsement record for the pilot. The ATSB reviewed the pilot’s flight training records for the Pitts Special and concluded that the activities were consistent with transition training onto the Pitts Special, which included stalls and spins, and not an aerobatics course.

The ATSB spoke to a member of a local aerobatics team, who knew the accident pilot, and they confirmed there had been discussions about the possible use of the accident pilot to ferry their Pitts Special aircraft to an airshow at the end of August 2024. However, the pilot did not meet the minimum experience requirements for insurance purposes and the plan was cancelled.

On 9 November 2024, a general aviation flight instructor and RAAus CFI conducted a check flight with the accident pilot at the Echuca Aero Club in the club’s Piper Archer aircraft. This was a requirement to be able to hire the aircraft. The instructor conducted a standard aerial work check flight with the pilot and did not identify any deficiencies in flying skills. 

Theory examinations

Recreational aviation theory examinations

The pilot’s logbook had a record of aviation theory examinations (exams) in accordance with the following table:

Table 3: Pilot's theory exams

The AFT CFI was recorded as the delegate for all of the pilot’s theory exams in their logbook. Another AFT instructor reviewed the exams recorded in the pilot’s logbook and reported that:

• the theory exams were conducted online and unsupervised
• the correct answers to all questions were revealed after the first attempt so that any incorrect answers could be corrected with a second attempt
• no knowledge deficiency reports were provided. 

The ATSB reviewed the software used by AFT to conduct the theory exams and found that the settings allowed multiple attempts and revealed all the correct answers in a report provided to the candidate.

PPL(A)-equivalent examination

To become a senior RAAus instructor, a candidate must pass either the RAAus PPL(A) (aeroplane) equivalent exam, or the CASA PPL(A) exam. The RAAus PPL(A)-equivalent exam was a multi-choice exam in which each question had 4 options to select from. 

On 3 January 2024, RAAus received the pilot’s application for upgrade to senior instructor, certified by the AFT CFI as the examiner, with a copy of the pilot’s instructor exam from 21 May 2023 attached. This exam was completed using the AFT online system. The ATSB did not find a record of the initial response to this application but based on the available evidence, it is likely that RAAus staff identified that the incorrect exam had been submitted in support of the application and reported this to the AFT CFI.

On 12 January 2024, the pilot completed the RAAus PPL(A)-equivalent exam using the AFT online system and a pass mark of 94% was recorded. However, the marking rubric for this exam had not been provided to AFT as this exam was marked by RAAus staff. As no marking rubric was provided, the AFT exam software provider had set answer ‘A’ as the default correct answer to all questions for this exam and notified the AFT CFI of this action. The accident pilot had selected answer ‘A’ to 47/50 questions.

When a copy of the pilot’s exam was provided to RAAus and re-marked it was identified that the actual result for the accident pilot’s exam was 26% (13/50).

On 29 January 2024, RAAus sent an email to the AFT CFI to report the result and express their concern about the result and the process used to mark the exam. They also notified the CFI that the pilot’s application for senior instructor would not be processed and that the pilot would:

• need to complete another PPL(A)-equivalent exam
• continue to require direct supervision (in-person) when instructing.

Re-attempt of PPL(A)-equivalent exam

On 24 February 2024, an external CFI[9] supervised the pilot’s re-attempt of the RAAus PPL(A)-equivalent exam at Moama Airfield. This CFI reported that the pilot arrived with a copy of the exam paper questions and that after the exam was completed, the CFI submitted it to RAAus for marking. They did not follow up as to how the pilot obtained a copy of the exam paper. Instead, they passed the information on to RAAus, who also did not enquire how the pilot had obtained the exam questions.

The AFT CFI reported that they believed the pilot had taken a blank answer sheet and not a copy of the exam paper to the exam. The answer sheet is a document with a table for the candidate to annotate the answer to each question. However, the pilot annotated their answer to each question on a copy of the exam paper, not an answer sheet, and it was this exam paper that was certified by the supervising external CFI and submitted to RAAus for marking.

The second exam result, marked by RAAus, was 76% (37/50), which was less than the required pass mark of 80%. This was the same exam paper, with the same questions and answers, that the pilot had previously attempted in January.

Pilot exam outcomes

The RAAus PPL(A)-equivalent exam included 3 questions about aerodynamic stalling, including about factors that change the 1G level flight stalling speed. For the pilot’s attempt on 12 January 2024, the pilot selected answer A to all 3 questions and they were all marked correct. However, 2 were correct and 1 was incorrect according to the RAAus marking rubric. 

For the pilot’s re-attempt on 24 February 2024, the pilot changed all 3 answers with the result that 1 was correct and 2 were incorrect. While the pilot correctly answered one question that the stall speed increases in a steep turn, they incorrectly answered another question about the relationship between angle of bank, load factor and stall speed.

On 29 February 2024, RAAus sent an email to the AFT CFI to report the failed second exam attempt by the pilot. On this occasion they stated:

Of more concern is the type of errors made, which include several stalling questions and poor Part 91 regulatory understanding among other items. I understand you have already spoken to [the pilot] and advised [them] of this, but I will call [them] to discuss as well.

RAAus expressed concern about the reported preparation process of reviewing current exam papers which ‘could be considered an attempt at rote learning of questions rather than developing a deeper understanding of the underpinning knowledge required of a RAAus Senior Instructor.’ RAAus reiterated previous comments they had made, that the pilot should re-attempt the exam ‘only after appropriate study of aviation textbooks and regulatory references.’ 

The ATSB noted other incorrect questions of concern for an instructor, in addition to the questions about stalling and Part 91 regulations identified by RAAus. They included knowledge of the instruments affected by a blocked static pressure system and the interpretation of an aerodrome weather forecast. The questions about stalling and pressure instruments were in the RPC syllabus, and knowledge of weather forecasts and reports were in the navigation endorsement syllabus. At the time they were attempting the PPL(A)‑equivalent exam, the pilot was delivering instruction for both syllabi. 

The ATSB queried RAAus as to whether they had considered imposing any restrictions or limitations on the pilot’s instructor rating after the second exam result, noting their concern about the pilot’s knowledge deficiencies. RAAus responded that by not processing the pilot’s upgrade to senior instructor, the pilot was required to remain under the direct supervision of a CFI, which was their risk management strategy until the pilot’s knowledge deficiencies could be addressed.

A copy of the 29 February 2024 email sent from RAAus to the AFT CFI appeared on the accident pilot’s RAAus member file. However, the pilot’s member file did not include any record of a follow-up about the exam result or progress towards completing any further attempts. Phone call records indicated that a follow-up from RAAus to the pilot did occur on 29 February 2024, but the details of the call could not be recollected. 

Commercial pilot theory examinations

Instead of studying the CASA PPL theory, the pilot started studying for their CASA aeroplane commercial pilot licence (CPL-A) theory component, which consisted of 7 exams. The pilot attempted and passed their first CPL-A exam on the subject of aircraft general knowledge (CSYA) with a result of 93% on 10 July 2024. The knowledge deficiency report (KDR) had 3 items listed, which indicated a score of 37/40 questions answered correctly. 

On 25 July 2024, the pilot attempted, and failed, the CPL-A aerodynamics exam (CADA) with a result of 63%. The KDR had 15 items listed, which indicated a score of 25/40. The incorrect answers were from a range of topics that included 2 questions on stalling. The 2 incorrect answers on stalling included the effect of using ailerons when approaching and during the stall, and the effect of manoeuvring on the level flight stall indicated airspeed.

On 7 August 2024, the pilot re-attempted the CPL-A aerodynamics exam and passed with a result of 75%. There were 10 items in the KDR, which indicated a score of 30/40. The 2 CPL-A aerodynamics exam KDRs included 3 errors in each of the topics of stalling, stability and control (longitudinal, lateral and directional), and control surface feature. Other items on the KDRs included:

• the lift and drag formulae
• dynamic pressure
• basic forces on an aircraft in level flight
• factors affecting turn performance
• angle of attack required for various flight situations.

Risky flying behaviour and counselling

Background

During the investigation the ATSB interviewed the AFT CFI and associates of the pilot, including:

• 2 other instructors from AFT
• 3 AFT RPC graduates from Moama
• the airport operator, who was also a local aerobatic pilot
• a local general aviation instructor and RAAus CFI. 

Each of them recalled experiencing instances of risky flying behaviour involving the accident pilot, or knowledge of this behaviour and counselling. The ATSB also interviewed RAAus staff to determine if they had received any reports of the pilot engaged in risky flying behaviour.

Risky flying behaviour

A fellow AFT instructor from Moama, who was also a syndicate member in the purchase of the aircraft, reported that the accident pilot had a history of conducting low and slow steep turns. While they had steep turn flying training experience themselves, they were accustomed to entering a steep turn from cruise airspeed and were concerned about the pilot’s practice of entering steep turns at slow speed. They had experienced this personally as a passenger with the pilot, as they were co-owners of a Jabiru aircraft, and were aware of reports of similar instances from the pilot’s students. 

The instructor had also witnessed the pilot conduct dumbbell turns in the circuit with students in light wind conditions. This involved the pilot conducting a reversal turn shortly after take-off to land on the reciprocal runway for student landing practice, rather than completing a full circuit between landings. They suspected the pilot had learned this from the AFT CFI as they had previously witnessed the CFI conduct this same manoeuvre in light wind conditions.

The other member of the syndicate in the purchase of the aircraft was an AFT RPC graduate from Moama in 2024. While they had conducted their RPC at AFT, they did not fly with the pilot until near the end of their flying training, at which point they were doing most of the flying. They did not observe any risky flying behaviour from the pilot but were advised by others at the school that the pilot had previously received counselling for risky flying behaviour.

Another fellow AFT instructor reported that the pilot could fly an aircraft well but ‘pushed the limits’. They recalled an example of a private flight in the pilot’s Jabiru, in which the pilot held the aircraft on the runway as it accelerated significantly beyond the take-off speed and then performed a pull-up into a steep climb. They stated that they immediately asked the pilot to lower the nose.

During the same flight, the pilot reportedly conducted low-level steep turns and a swooping manoeuvre over a friend on the ground. The instructor reported that they repeatedly verbally intervened throughout the flight, and that they didn’t like how the pilot was flying and asked them to stop and return to the airport after about 30 minutes.

Another AFT RPC graduate from Moama reported that during a local recreational flight on 1 November 2024 in the pilot’s Jabiru, which had a stall airspeed of 45 kt, the pilot conducted a low-speed steep turn overhead a friend driving a tractor. The combination of low speed and steep angle of bank made them feel uncomfortable and they assessed that the aircraft did not have sufficient lift for the manoeuvre. The pilot reportedly noticed their discomfort and told them not to worry as they were still at 60 kt (airspeed). ADS-B data recorded a minimum groundspeed of 57 kt during this turn. 

The AFT graduate had previously conducted their RPC pre-check flight with the pilot in August 2023, which included stalls and steep turns in a Topaz aircraft with a stall speed of 44 kt. They reported that the steep turns demonstrated by the pilot then were at least 60° angle of bank, which made them feel uncomfortable and they noted that the pilot appeared to be pushing the aircraft to its limits in a confident manner.

Another RPC graduate interviewed by the ATSB had transferred from the CASA-issued PPL system to the RAAus-issued RPC system and completed their flying training with AFT at Moama. Three days prior to the accident, the pilot invited them on a local area private flight in the accident aircraft. During the flight, the pilot reportedly turned off the transponder and conducted a low-level, high-speed pass over a friend’s house, followed by a wingover.[10] The pilot then demonstrated the responsiveness of the aircraft by conducting a series of level steep turns. The witness reported that the angle of bank was more than 60° and felt like 70–75°, which they described as ‘knife-edge stuff’.

Counselling

The Moama Airfield operator and local aerobatic pilot knew the accident pilot from the AFT school at Moama. The operator had taken the pilot flying in their own aerobatic aircraft and found them to be a very enthusiastic young aviator. Their impression was that the pilot was attracted to the sport aviation side of the industry. In September 2024, the operator was contacted by the AFT CFI about reports of unsafe flying, which included instances of low-level flying and manoeuvring overhead a local football match. 

The airfield operator investigated the reports and found that it was likely the accident pilot who had been conducting steep turns overhead the Moama football ground during a match. They approached the pilot in late September and stressed the need for them to fly respectfully and emphasised staying above the minimum requirements and not to orbit overhead properties. They thought that the pilot accepted the counselling in a positive manner.

A local general aviation instructor and RAAus CFI, who was involved in establishing an FTS near Moama, also received a report that the pilot had been observed conducting aerobatics overhead a local football match. They responded to the reporter that the pilot would not be allowed to instruct for the school with that flying behaviour. The pilot subsequently contacted the CFI and visited them on the afternoon of 1 November 2024 to discuss the reported incident. The pilot was reportedly adamant that they had not conducted aerobatics overhead the football match but acknowledged that they had conducted steep turns overhead the match. 

At the time of the visit, the CFI had also heard reports that the pilot had been conducting dumbbell turns in the circuit with students. Consequently, they used the visit from the pilot as a counselling opportunity, specifically pointing out that a solo student might try to imitate the pilot’s flying and lose control of the aircraft. The CFI thought that the pilot accepted the counselling in a positive manner. 

The AFT CFI reported to the ATSB that prior to the cessation of AFT operations in August 2024, they had regularly engaged in coaching and counselling sessions with the pilot. However, after they ceased AFT operations, they received multiple calls from members of the local community raising concerns about a Jabiru aircraft flying in a manner perceived to be unsafe. While the pilot was not confirmed, the context of the reports led them to believe that the flights were operated by the accident pilot.

The AFT CFI reported that several weeks prior to the accident they had a candid conversation with the pilot and urged them to continue flying safely and responsibly. They stressed that the pilot needed to be even more alert and disciplined without direct oversight. However, as they were no longer responsible for formal oversight of the pilot, they elected to contact others who could potentially mentor the pilot. This included the Moama Airfield operator.

RAAus advised the ATSB that, prior to the accident, they had not received any reports or complaints about the pilot’s flying behaviour, nor were they aware of the pilot receiving any counselling. However, following the accident, they received a report from the AFT CFI that they had been managing the pilot’s behaviour. 

RAAus interrogated their occurrence management system for any complaints involving unidentified aircraft and/or pilots in the Moama region and found none. They stated that if they had received a report of an instructor involved in risky flying behaviour, there would have been a ‘fairly swift response’ because they would not want the individual working as an instructor, and potentially indoctrinating students to that behaviour.

Recreational Aviation Australia

Structure

Recreational Aviation Australia (RAAus) is a CASR (Civil Aviation Safety Regulation) Part 149 approved self-administering aviation organisation (ASAO). In 2025, RAAus had 14–15 full time employees in the following areas:

• flight operations
• maintenance and airworthiness
• safety
• finance
• information technology
• administration. 

According to the RAAus website, they had 10,000+ members in 2025, and were the largest administrator of pilots, maintainers and aircraft in Australia.

RAAus were authorised by CASA to conduct their activities in accordance with their approval certificate, the Part 149 Manual of Standards and their approved Part 149 Exposition. As a sport aviation organisation, RAAus was oversighted by the CASA Sport and Recreation Aviation Branch (CASA Sport). 

The structure of RAAus, with their key personnel in accordance with their Exposition, is depicted in Figure 11.

Figure 11: Recreational Aviation Australia structure

Source: Recreational Aviation Australia

The RAAus Part 149 approval certificate authorised RAAus to administer several aviation administration functions and their sub-functions. The function of relevance to the ATSB’s investigation was Part 149 Flight Training Organisations:

Administer a person that conducts flight training, or flight tests, in relation to a Part 149 aircraft.

The sub-functions were listed as follows:

1. Assessing a person’s organisation, and its procedures, practices, personnel and facilities to determine whether the person is capable of conducting flight training, or flight tests, in relation to the aircraft

2. If satisfied as mentioned in paragraph 1, issuing an authorisation to the person to conduct the activities specified in the authorisation

3. Assessing whether a person to whom the ASAO has issued an authorisation continues to be capable of conducting the activities covered by the authorisation

4. Approving aeronautical examinations that may be conducted by a Part 149 flight training organisation to assess candidates undertaking flight training.

Flight training schools 

In 2025, there were about 160 RAAus flight training schools (FTSs). Student pilots, converting pilots and pilot certificate holders could only undertake flight training with an RAAus FTS approved by the RAAus Head of Flight Operations (HFO). An FTS could only operate when a CFI was approved in accordance with the RAAus flight operations manual (FOM). The FOM also required FTS instructors to be directly supervised by the CFI, or another senior instructor approved by RAAus, with indirect (remote) supervision of senior instructors permitted.

In February 2022, RAAus published version 1.1 of their Recreational Aviation Advisory Publication on instructor supervision requirements. This was published to address the enquiries RAAus had received from their members about the instructions in the FOM. Direct supervision of instructors was in-person and was required to be provided by the CFI or approved senior instructor. The intention of the direct supervision requirement was to ensure the supervisor was physically present at the location where the training was conducted to provide continuing mentoring and development for their instructors.

The CFI oversight responsibilities included 90-day check flights of their instructors and 12‑monthly check flights of their senior instructors, which were called standards and proficiency checks. To become a CFI, an individual was required to progress through the qualifications of RPC, instructor and senior instructor. A senior instructor could be appointed to supervise an FTS in the CFI’s absence if they met the requirements of the RAAus FOM and were approved by the HFO. 

Flight training school exams

Each RAAus FTS qualification had a flight test and one or more associated theory exams. The theory exams were written by RAAus and sent to the FTS CFIs via email. For each exam, answer sheets were provided for the candidates to record their answers to a selection of multiple-choice exam questions. The syllabi for the theory exams were published in the RAAus syllabus of flight training. 

Before accessing the exams, each CFI was required to sign a declaration acknowledging that they had read the conditions of use and would ensure the necessary processes had been implemented at their FTS. The declaration included:

Multiple Choice Examinations. These are not to be distributed and/or reproduced electronically and must be stored securely. 

The FTSs were provided with the marking rubric for each exam and were responsible for marking, filing and recording of the results of each exam. The exception to this was the upgrade from instructor to senior instructor for which the exam requirement was either the CASA PPL(A) exam or the RAAus PPL(A)-equivalent exam. RAAus marked the PPL(A)-equivalent exam and did not provide the FTSs with the marking rubric for it. Prior to 2023, RAAus did not require proof of completion of any exams. In 2023, the RAAus instructor upgrade form was amended to require proof of exam completion for the upgrade to senior instructor only. 

Flight training school oversight 

The RAAus Exposition included an audit program to fulfill sub-functions 1 and 3 of their Part 149 Flight Training Organisations function. Sub-function 1 was for the assessment to issue FTS status while sub-function 3 was for the monitoring of the FTS, which was required to be conducted at least once in every 2-year period.

The RAAus audit activities included:

• desktop
• onsite
• special purpose audits
• health checks
• periodic reviews
• renewals.

The CFI was the only individual from the FTS who was required to be in attendance for an onsite audit and was interviewed as part of the audit process. Other staff members could be interviewed on an opportunity basis, but students were not interviewed as part of a routine audit. 

Given the large number of FTSs and the limited number of RAAus staff available for oversight, RAAus developed a risk and audit matrix to determine the type and frequency of audit activity. The matrix produced a performance indicator (PI) score for each authorisation holder. The RAAus audit manual provided the following statement for FTSs assessed as higher risk:

Where resourcing permits, authorisation holders who fall within the highest 10 PI [performance indicator] scores shall only be eligible for an on-site audit and should be scheduled within the following 6 months. 

When an authorisation holder within the highest 10 PI scores was scheduled for an onsite audit, the audit team would identify other authorisation holders within the local area who would also be audited during the visit.

Occurrence management system 

RAAus had an occurrence and complaints management system (OCMS) database supported by an occurrence and complaints handling manual (OCHM). According to the OCHM:

Any person may report a safety concern or confidential complaint relating to an RAAus member and aircraft. A confidential occurrence may be lodged through the RAAus Occurrence and Complaint Management System (OCMS).

Apart from those OC [occurrences] that are resolved immediately by front line staff, all OC will trigger an informal assessment.

An informal assessment will be made to obtain and assess sufficient information to determine the most appropriate course of action, including the possibility of a Safety Related Suspension [SRS] if a serious safety situation is indicated.

The OCHM described the SRS as follows:

Temporary suspension of a member’s privileges, through imposing an SRS, is a risk management strategy that will be considered if:

a. the potential risk (to self, other RAAus members, members of the public, the organisation or the effective conduct of the investigation) posed by the member continuing to fly, or maintain aircraft, is significant; and/or

b. the potential risk to others posed by the member cannot reasonably be managed in any other manner.

The AM [Accountable Manager], HAM [Head of Airworthiness and maintenance] or HFO may decide to impose an SRS on a member.

The OCHM provided the following examples of an SRS:

a. enhanced supervision requirements

b. temporary suspension of certificates

c. temporary revocation or restriction of privileges.

In accordance with CASR 149.425 and the RAAus Exposition, RAAus was required to submit a written report to CASA within 7 days of taking formal compliance or enforcement action. This was described in the RAAus formal inquiry process.

RAAus advised that mandatory notification to CASA was not required following an SRS because it was part of their informal assessment process and not their formal inquiry process. However, they could notify CASA of an SRS at their own discretion if they considered it prudent, although there was no continuing reporting requirement associated with this.

The outcome from an informal assessment could include a requirement for remedial action to be completed prior to lifting an SRS. If an individual’s membership lapsed with an active SRS, the requirements remained in place, flagged in their RAAus member profile, and were to be completed prior to exercising the privileges of their RPC if they decided to reactivate their RAAus membership.

Adventure Flight Training

Background

The AFT CFI became a member of RAAus in December 2008 and was issued with an RPC in December 2009, instructor rating in April 2017 and senior instructor rating in July 2018. On their senior instructor upgrade submission to RAAus, the examiner certified that the ground theory component was satisfactorily completed, although proof of completion of the ground theory was not required and not provided. Proof of a current medical certificate was required and provided. 

As previously described, the theory component for the upgrade to senior instructor could be met by either passing the CASA PPL(A) exam or submitting the RAAus PPL(A)‑equivalent exam for marking by RAAus. In the case of the AFT CFI’s senior instructor upgrade, RAAus reported that the answer sheet for the PPL(A)-equivalent exam was not received with the upgrade submission and that it was likely their administration staff believed that the CASA PPL(A) exam had been completed instead. The CFI reported to the ATSB that for their senior instructor upgrade, the RAAus PPL(A)‑equivalent exam was done, submitted and approved.

The CFI was issued with a certificate of approval for their FTS on 11 June 2019. This followed an FTS inspection report in May 2019 at the nominated location of Riddell Airfield (Riddell), Victoria, and was initially to provide training for the issue of an RPC. The first 3 RPC candidates were required to be independently assessed by an RAAus‑nominated examiner. 

In October 2021, RAAus issued the CFI with temporary approval for instructor training IT(T). This required the first 3 candidates for their instructor rating to be independently assessed by an RAAus-nominated examiner before the temporary approval could be lifted. In May 2022, RAAus conducted an onsite audit of AFT at Riddell. 

RAAus records indicated that on 6 March 2023, the primary location for AFT became Moama. In August 2024, RAAus imposed an SRS on the CFI, which suspended their CFI approval and senior instructor qualification. Subsequently, the CFI elected to cease the FTS operations and later sold AFT. 

Practices at Riddell Airfield 

As part of the investigation, the ATSB interviewed the AFT CFI, 2 AFT instructors who were peers of the accident pilot, and several AFT RPC graduates from Riddell and Moama Airfields, all of whom knew the CFI and the accident pilot. 

The interviews with those who had trained at Riddell indicated that AFT operations appeared to be consistent with the RAAus Exposition for an FTS, which was the situation when AFT was audited by RAAus in May 2022. One RPC graduate from Riddell reported that it was a more positive learning environment than they had previously experienced in general aviation.

The CFI would deliver the theory during the classroom lesson, then demonstrate the manoeuvre in-flight before handing over control and directing them how to fly the manoeuvre. Theory exams were paper-based using the exam papers provided by RAAus, which were supervised, marked and debriefed by the CFI. 

However, what also emerged from the interviews was a difference in the FTS practices between Riddell in the period 2019–2023 and Moama in the period 2022–2024.

Onsite audits 

In May 2019, RAAus conducted an initial FTS inspection at Riddell, and an FTS inspection report was completed by the RAAus delegate. No non‑compliances or rectifications were recorded on the report. At the time, there were no satellite flight training facilities and therefore the requirement for inspections of these facilities was recorded as not applicable on the report. 

The next onsite audit of AFT was conducted at Riddell by RAAus in May 2022, at which time Moama was recorded as a satellite facility. That audit only occurred by virtue of AFT being at the same airfield as another FTS at Riddell being audited due to their PI being in the top 10. RAAus reported that, prior to that audit, AFT was ranked about 20 based on their PI score. 

RAAus reported that during the 2022 audit they checked the records of student exam results but would not have checked the exam papers (answer sheets) themselves. One member of the audit team recalled a discussion with the CFI about the use of an online exam system as part of a broader discussion about how to improve the administration of the FTS. They did not believe an online exam system was in use, and they did not review or approve one. 

The 2022 audit report included a reference to checking exam results but no reference to the use, or discussion, of an online exam system. RAAus reported that they had declined requests by FTSs to use online systems because it conflicted with the CFI declaration to not distribute the exams in either electronic or paper form.

On review of the draft report, the CFI maintained that RAAus did approve their online exam system and that they demonstrated it to 2 of the auditors during the 2022 audit. They further reported that during the audit they reported that exams were completed and stored electronically and demonstrated this in accordance with the respective audit checklist item. However, the auditor’s annotation on the 2022 audit report next to this item indicated ‘Cloud based (Google Drive)’ and did not include reference to the online exam software platform.

The audit resulted in 2 required corrective actions and 5 observations with associated recommendations. The AFT CFI responded to the corrective actions required and observations, which were accepted by RAAus. A copy of the audit closure report with the accepted supporting evidence was sent to the CFI in August 2022. 

RAAus reported that, depending on findings, an FTS did not automatically move to the bottom of the PI score list after an audit. In this instance, because of the structure of AFT and the non-compliances identified during the audit, their rank moved from about 20 to approximately 100 (of about 160 FTSs at the time).

Chief flying instructor conduct

In May 2020, RAAus investigated a close proximity event involving the AFT CFI, which their risk matrix indicated was a potentially catastrophic event. The CFI denied involvement in the event and reportedly provided RAAus with a copy of their flight path history for the day of the incident. However, the RAAus investigation confirmed it was the CFI’s aircraft and that they were aboard at the time. RAAus subsequently issued a formal letter of reprimand to the CFI for not reporting the event and denying their involvement.

In August 2020, the initial cadre of AFT RPC candidates were ready for assessment, and an independent examiner was nominated by RAAus. The examiner assessed the first candidate and reported to RAAus that the flight component of the test went smoothly but the candidate’s theory knowledge was ‘not as good as it could have been’. The examiner recommended the candidate do further theory practice exercises. 

RAAus correspondence indicated that following the independent assessment of the first AFT RPC candidate, the CFI conducted the flight tests for the 2 other RPC candidates, instead of having them assessed by the nominated examiner as required. When RAAus challenged the CFI about this matter, they alleged that the examiner had lost control of the aircraft during the flight test with their candidate. This allegation was later challenged by the examiner and the CFI provided RAAus and the examiner with a retraction.

On review of the draft report, the CFI denied that they had made this allegation and reported that the student had told them the examiner was flying out of balance. Therefore, the CFI decided to request another examiner with experience on that aircraft type conduct the checks. 

In December 2020, RAAus lifted the RPC testing restriction on the CFI with an administrative assessment in place. This allowed them to conduct the flight tests for the recommendation of an RPC but required them to provide RAAus with each candidate’s completed training records when the RPC recommendation paperwork was submitted.

In November 2021, about a month after RAAus issued the CFI with their instructor training temporary approval (IT(T)), the CFI advised RAAus they were starting a full-time IT course at Moama Airfield. Like the first 3 RPC candidates, the first 3 candidates for the instructor rating were required to be independently assessed.

In April 2023, the CFI reported to RAAus that their first 3 instructor candidates had been independently assessed and requested removal of their temporary IT status. However, the examiner on this occasion (different from the previous RPC examiner discussed above) reported that the candidates were not prepared for their instructor briefing session despite the preparation advice the examiner had provided to the CFI for their candidates. 

The examiner also reported that there were additional administration preparation deficiencies, which led them to conclude that the CFI had not taken the time to check the process requirements. Consequently, in May 2023, RAAus notified the CFI that they would need to remain under a temporary IT approval status until a further 2 candidates could be assessed by the same examiner. The RAAus records indicate that the temporary IT approval was never lifted. 

Practices at Moama Airfield

Pre-flight video briefs

The accident pilot started flight training with AFT at Moama in April 2022 with operations temporarily moving to Echuca, Victoria, during the flooding of Moama in late 2022. Staff and students interviewed by the ATSB who attended Moama from late 2022 through to the closure in August 2024 reported that no pre-flight briefings or post-flight debriefings were delivered for RPC candidates. Instead, the CFI had produced a short in-flight video for each of the RPC flight training elements, which demonstrated how the manoeuvres were to be flown, and candidates reported they had to pay a subscription fee to access AFT flight training videos for pre-flight briefing material. 

On review of the draft report, the CFI reported that the videos were gradually introduced from 12 July 2023 to 22 July 2024. Therefore, the videos were not used for the delivery of training to the accident pilot, which they reported was delivered in-person.

The CFI reported that the videos were only introductory material and not the pre-flight briefing material. However, the CFI’s position was contradicted by the Moama AFT instructor staff and students interviewed by the ATSB. Additionally, the ATSB noted that the syllabus used by AFT staff included the following items:

Confirm student has watched the relevant video briefing and understood the concepts

Remind students to login to AFT members page and watch next video

According to RAAus, their Exposition did not prohibit an FTS from implementing pre-flight video briefings in lieu of in-person pre-flight briefs. However, RAAus advised being unaware of the videos prior to suspending the CFI in August 2024. RAAus learnt about the videos from interviews with AFT members about the practices at the FTS. However, they were then told by the CFI that access to the videos was no longer available and therefore, RAAus reported they were unable to assess whether the content of the videos was adequate. 

The ATSB interviewed an RAAus CFI, who was also a CASA flight instructor, and who had reviewed one of the videos. They reported that they didn’t think the video met the quality required for a pre-flight brief. Another RAAus CFI, who had reviewed several of the videos for the AFT CFI, reported to the ATSB that they had been led to believe that they were the pre-flight briefing material and that they were inadequate due to deficiencies in the quality of instruction presented.

They noted that, while the AFT CFI was projecting a friendly demeanour in the videos, it was often at the expense of technical errors and an adequate demonstration. For example, the reviewer noted the stalling video did not include any reference to the effect of load factor on stall speed and reference to checks and limits were often omitted in the various videos. 

The ATSB obtained copies of 12 of the AFT videos from elements of the RPC syllabus, one produced in 2020 and the remainder in 2023. This evidence was consistent with a report the ATSB received from a Moama AFT instructor that they were already receiving video briefs when they started flying training in late 2022. They ranged in length from 2 minutes and 15 seconds to 7 minutes and 30 seconds. Of specific interest to the ATSB investigation was the aerodynamic stalling video, which was of 6 minutes duration.

In that video, the CFI demonstrated the reduced effectiveness of flight controls near the stall by applying full left then full right rudder and instructed the use of rudder to level the aircraft if a wing drop occurred. The risk of inducing a spin from large rudder applications near the stall was not mentioned. By contrast, the CASA flight instructor manual for aeroplanes explained these points in its chapters on stalling and spinning as follows:

Emphasize that if a wing drops, rudder is used to prevent yaw into the direction of the lowered wing. The wing is raised with aileron when it is un-stalled.

An aeroplane is made to spin, whether accidentally or deliberately, by faulty use of the controls particularly the rudder.

During the stalling video, the CFI explained that lowering the flap for the configured stall demonstration would ‘thicken’ the wing, and that the thicker the wing, the slower they could fly. The manufacturer’s website for the demonstration aircraft stated that it had a slotted flap. A slotted flap is a design feature used to control the boundary airflow layer and increase the camber of the wing. Lowering the flap increases the maximum coefficient of lift (and drag) for the wing, thereby allowing the aircraft to fly and stall at a lower airspeed and is part of the basic lift formula. 

At the start of the video, and in accordance with the RAAus syllabus of flight element of stalling, the CFI demonstrated the pre-manoeuvre checks. However, there was no reference to flap limiting speeds for the configured stall and no demonstration of post loss of control checks after recovery from any of the stalls. The RAAus syllabus of flight included ‘airframe limitations’ as a competency requirement within the element of stalling.

Demonstration of stall at greater than 1G

For the RAAus RPC syllabus, stall exercises were limited to straight and level, clean and configured stalls, with and without wing drops, which were covered in the AFT video. However, the RPC theory syllabus did require a thorough understanding of the relationship between load factor and stall speed and the instructor syllabus included demonstration of stall entry at greater than 1G (critical angle of attack exceeded at a higher airspeed). In the AFT stalling video, the CFI directed the viewer’s attention to the lower stall speed when the flap was lowered for a configured stall, but a higher stall speed, and what contributes to a higher stall speed, was not demonstrated or discussed. 

The CFI reported that the demonstration of stall entry greater than 1G was conducted in training, but the 2 AFT instructors interviewed by the ATSB reported they did not conduct this manoeuvre during their training. One of the instructors reported that they were unaware of the effect of load factor on stall speed at the time of the accident and that both themself and the accident pilot were trained in stalling by the AFT CFI for their instructor course. Therefore, they believed the accident pilot would not have covered this topic either. Their main concern with the load factor applied by the accident pilot during steep turn manoeuvres was the potential for a structural failure.

While the CFI reported that the ‘greater than 1G stall manoeuvre’ was taught as a turning stall during training, they were unable to recall the parameters used for the demonstration. The AFT records for their instructor training courses included comments about clean stalls, configured stalls and wing drops. However, there were no references to a stall at greater than 1G.

The AFT RPC student records indicated that the element ‘critical angle of attack exceeded at a higher airspeed’, was assigned a competency code on 46 out of 55 occasions. This was despite it not being in the RPC syllabus and the AFT instructors interviewed by the ATSB reporting that they had never done it in training themselves or with a student. One instructor explained that the competencies for each flight were accessed during the flight with a portable electronic device, such as a smartphone, and that on a small screen, instructors might have only registered the start of the competency, which stated ‘critical angle of attack exceeded…’, without either registering or understanding the meaning of the rest of the competency, which stated ‘…at a higher airspeed’. 

Online exams

The AFT instructor interviewed by the ATSB, who started flying training with AFT at Riddell Airfield, reported that they followed the RAAus paper-based exam system, as previously described, and that they had no experience with an online exam system. However, the other instructor interviewed by the ATSB, who started at Moama Airfield (Echuca during the floods), conducted their exams at home, unsupervised using their own login to the AFT online exam system. This was the same process described by the AFT RPC graduates from Moama interviewed by the ATSB. 

The CFI reported that the online exam system was set up in response to the COVID lockdown period and was approved by RAAus. The setup of the system entailed the CFI providing a copy of each exam paper and marking rubric to the software platform provider for loading onto their platform. The exception was the RAAus PPL(A)-equivalent exam, which was marked by RAAus and therefore no marking rubric was provided. The CFI reported that the software provider loaded answer A as the default correct response to all questions for the PPL(A)-equivalent exam and notified them of this action.

The AFT cohort who used the online exam system paid a subscription to access the exams and were notified by the CFI or their instructor when they were due to complete an exam. The CFI was the administrator for the online system and reported that the security protocols prevented anyone else from downloading or printing a copy of an exam paper. As the administrator, the CFI included settings which allowed 2 attempts at each exam and revealed the correct answers to all questions in the exam report, provided after the first attempt. 

One of the Moama RPC graduates reported there was no study direction before an online exam and that the staff expected they would pass each exam on a second attempt if required. This graduate reported there were no classroom lessons, in addition to no in‑person pre-flight briefs, and the lack of theory education caused them progression problems and learning difficulties with some of the technical aspects. 

Another Moama RPC graduate, who had prior non-aviation teaching experience, believed the online exams were open-book as they were unsupervised. Consequently, they used their flight training reference books during exams, supported by online searches for any questions they could not find the answer to in their books.

They did not pass their first attempt at the basic aeronautical knowledge exam but received all the correct answers in their exam report, which they photographed and used for their second attempt. They did not receive any classroom lessons or pre-flight briefings at AFT and reported that they felt the learning experience was substandard.

The RPC graduate had 2 attempts at the basic aeronautical knowledge exam on the same day recorded in the AFT exam records, with a score of 100% for both attempts. One of the AFT instructors reported to the ATSB that the exam scores were manually entered and might not have represented the actual results. Of the 146 entries in the AFT exam records, from April 2021 to July 2024, there were no failures.

Deficient instructor supervision

As previously described, on 19 December 2023, the AFT CFI conducted the senior instructor flight test for the accident pilot and incorrectly submitted the upgrade application to RAAus with a copy of the pilot’s May 2023 instructor exam, which had been conducted online. On 3 January 2024, the CFI certified in the pilot’s logbook that they met the requirements for the senior instructor rating in accordance with the RAAus syllabus of flight. The pilot subsequently took the RAAus PPL(A)-equivalent exam online on 12 January 2024. 

The pilot scored 94% (47/50), noting answer A was the default correct answer for all questions, and which the CFI reported that they were aware of. The CFI then submitted a copy of this exam to RAAus, noting that they reported that they were the only one who could download the exams from their online platform. 

In late January, RAAus notified the CFI of the pilot’s failure assessment for the PPL(A)‑equivalent exam, that the pilot’s upgrade to senior instructor would not be processed and that the pilot would continue to require direct supervision as an instructor. However, in January 2024, the CFI left the FTS for extended travel around Australia throughout the calendar year 2024. 

Prior to leaving, the CFI enquired with another RAAus CFI if that person could hold a temporary CFI position for them while they were away. However, they were told by that person that they could not attend the FTS in Moama and were therefore unable to comply with the direct supervision requirements for the AFT instructors. There was no reference in the AFT CFI’s RAAus member record of their absence from their FTS and RAAus reported they had no knowledge that the CFI had departed from the area and left their instructors without direct supervision.

The accident pilot’s last logbook entry was an AFT instructional flight on 7 August 2024 and their last check flight with the CFI was their senior instructor flight test on 19 December 2023. There were no entries in 2024 for a standards and proficiency check from the CFI, which was required every 90 days. 

The AFT training records indicated that the CFI was at the FTS until at least 11 January 2024 and returned to deliver training for several days in February, May and June of 2024. One of the AFT instructors reported they didn’t get a check flight from the CFI during one of the visits, which concerned them as they considered themself and the other instructors at AFT to be relatively ‘green’.

The other AFT instructor reported that the flights they conducted with the CFI during this period were ferry flights between Melbourne and Moama when the CFI visited the FTS to deliver training. The 3 AFT instructors all qualified in 2023_; one in early 2023, the accident pilot in mid-2023 and the third in late 2023.

Examination conduct

As previously described, the accident pilot unsuccessfully re-attempted the PPL(A)‑equivalent exam on 24 February 2024. At the end of February, RAAus emailed the CFI the result from the pilot’s second attempt at the exam and their concern about the type of errors made. They also advised the CFI that it was critical for the CFI to also complete the PPL(A) exam as they had delivered the instructor training for the accident pilot and RAAus could not confirm that the CFI had previously completed the PPL(A) exam. 

In response, the CFI reported to RAAus that it was their intent to complete a PPL(A) course and the CASA PPL(A) exam. RAAus noted this but also committed to revising their PPL(A)‑equivalent exam by the end of March as an alternative pathway. In late March, RAAus requested an update from the CFI on their progress towards attempting the PPL(A) exam. The CFI reported that both they and the accident pilot were enrolled in a course but could not provide an estimated completion date. 

On 2 July the CFI submitted a completed exam paper to RAAus for the same version of the PPL(A)-equivalent exam that the accident pilot had failed in February (2022 version). However, RAAus noted that their policy for exam conduct, published at the front of the exam paper, was not followed. Specifically, a supervisor for the exam was required to be appointed by RAAus, the exam answer sheet should have been used instead of the exam paper, and the supervisor should have submitted the exam to RAAus for marking, rather than the candidate (the CFI themself). 

RAAus communicated the problems they identified to the CFI, and they subsequently received a copy of the exam answer sheet, with a supervisor’s signature dated 4 July. The answer sheet provided was marked by RAAus and scored as a pass (88%). RAAus prepared a knowledge deficiency report with the pass result for the CFI and annotated the exam location as ‘Supervised via zoom (possibly at Moama)’. 

On 8 July, RAAus followed up with the certifying supervisor on several points, which included:

Their instructor approval had lapsed in January and therefore their supervisory privileges had also lapsed.

How were they given approval to supervise the exam as the policy document states that the RAAus HFO makes these arrangements?

Exams require direct supervision, which is in-person, whereas the use of Zoom indicated indirect supervision.

The supervisor’s certification date of 4 July was 2 days after the exam paper was submitted to RAAus.

There was no record of answers to these queries, but RAAus subsequently concluded that the CFI’s exam result was invalid. At the end of July, they communicated to the CFI that either the CASA PPL(A) or a new RAAus PPL(A)-equivalent exam needed to be taken prior to 16 August 2024. 

The CFI notified RAAus on 7 August that they would attempt the PPL(A)-equivalent exam if it could be facilitated for them in Far North Queensland. This was arranged for 8 August with a copy of a new RAAus PPL(A)-equivalent exam (2024 version). The 2024 exam paper comprised 60 questions, of which 50 were the same, or similar, to the 2022 version. The CFI scored 77% (46/60), which was below the required pass mark of 80%. 

The CFI reported to the ATSB that other CFIs had told them that they too could not pass the 2024 version exam paper, and the CFI did not believe the exam had been validated and therefore should not have been used. They provided a specific example of a navigation question they believed was marked as incorrect because they used a protractor rather than the ‘1-in-60’ rule to calculate their answer to a heading correction question. However, the ATSB identified that it was possible to derive the correct answer using either method. 

The ATSB also noted that the CFI provided the same incorrect answer as the accident pilot to a question about the relationship between angle of bank, load factor and stall speed. They had both selected the answer with the correct stall speed but the incorrect load factor. The RAAus syllabus of flight training contained the references for the navigation and stall speed questions.

The marking of the CFI’s answer sheet revealed there were 13 incorrect answers in the first 50 questions (7 in common with the accident pilot) and 1 incorrect answer in the 10 additional questions. Consequently, if only the 50 questions from the 2022 version exam were marked, the score would have been 74% (37/50) and remained below the pass mark. 

Safety related suspensions

On 9 August, RAAus notified the CFI of the failed exam result and that the exam had been crosschecked by 2 independent staff. They then issued an immediate SRS, suspending the CFI’s senior instructor rating, which was required for a CFI approval. To remove the SRS, the CFI was required to supply RAAus with evidence of a pass result for the CASA PPL(A) exam. RAAus reported to the ATSB that they were prepared to arrange for a temporary CFI for AFT in the interim, but the CFI decided to cease FTS operations and later sold AFT.

On 13 August, RAAus notified CASA of their implementation of the SRS for the AFT CFI and that the matter was currently under review. The notification to CASA included:

• RAAus identification of incorrect marking of a PPL(A)-equivalent exam for a senior instructor candidate, which raised questions about the CFI’s theoretical knowledge
• advice of the CFI’s failed attempt at the PPL(A)-equivalent exam, with a conclusion that they therefore did not meet the theoretical knowledge requirement for the senior instructor rating and would need to provide evidence of a pass for the CASA PPL(A) exam. 

On 11 November, RAAus notified the AFT CFI that they had completed an informal assessment as per the OCHM and did not believe a formal inquiry was necessary. They reiterated that the remedial action required was the completion of the CASA PPL(A) exam. However, by that time the CFI’s membership had lapsed. RAAus reported to the ATSB that the remedial action requirement would remain flagged in the system in the event that the CFI elected to re-activate their membership and have their senior instructor rating reinstated.

Following the accident, on 19 December 2024, RAAus issued an SRS notice to all RPC graduates from AFT who did not hold a CASA PPL(A) licence or higher. This was due to non-compliances with the conduct and supervision of exams, which meant they could not verify that former students met the theoretical knowledge requirements for the issue of an RPC. 

Civil Aviation Safety Authority

Surveillance events

The CASA Sport and Recreation Branch (CASA Sport) conducted a Level 1 surveillance event of RAAus at their premises between 12–14 April 2023, and a Level 2 surveillance event at their premises between 3–5 September 2024. Prior to 2023, the previous audit was a Level 1 surveillance event on 4 May 2019. The ATSB obtained a copy of the previous 2 audit reports (2023 and 2024) of RAAus by CASA.

The May 2019 audit resulted in 1 finding and 6 observations. The April 2023 audit resulted in 4 findings and 7 observations. The 4 findings related to the elements of airworthiness and listing of aircraft and were not relevant to the ATSB’s investigation. However, one observation of relevance from the 2023 audit was for the element of Evaluation of Authorisation Holders, as follows:

The processes for the regular evaluation of holders of certain authorisations to ensure compliance with the requirements set out in the ASAO’s policies and procedures require additional development. 

As this was an observation, no response was required from, or provided by, RAAus. The September 2024 audit of RAAus followed their notification to CASA Sport of the SRS issued against the AFT CFI and the introduction to the audit report stated:

The auditors sampled the systems and elements relating to RAAus' oversight of flight training schools with the respective key personnel and the RAAus Accountable Manager. Emphasis was placed on reviewing:

• the integrity of their training/testing system which leads to the granting of pilot authorisations,

• governance and process including consistency,

• oversight of training and examining,

• safety assurance including the reliability of information provided by examiners.

CASA Sport raised 2 observations from the audit for competency-based training, and interpretation of manuals, which were both against the element of Flight Operations (Pilot Authorisations). No responses were required or provided to the observations. The observation about competency-based training had a similar theme to the 2023 audit observation about compliance issues and stated:

Current updates to the Flight Operations Manual (Version 8) places significant reliance on CFIs and Examiners applying competency-based training and testing outcomes. However, one of the highest individual non-compliances identified from the RAAus Risk and Audit Matrix Occurrence Tracker records has been deficiencies in the FTS applying and recording competency-based training outcomes (assessing and recording competence and rectifying deficiencies). 

The non-compliances found by RAAus auditors during the audits of FTSs - with more than 30% of the RAAus FTS surveillance events (conducted between Dec 2021 and August 2024) showing a non-compliance in relation to assessing and recording competencies - may suggest a level of guidance regarding competency-based training for FTS may be required.

Pilot examination office 

The CASA pilot online examination system is called the pilot examination office (PEXO). The key personnel in the daily operations of an examination centre are the registrar and invigilator. A registrar is responsible for making the booking of exams for candidates and an invigilator is responsible for the direct supervision of the candidates for their exams. An individual may hold both the registrar and invigilator positions.

Registrars, invigilators and examination centres must be authorised by CASA and the approval for FTSs to conduct exams is limited to PPL and the private instrument flight rating (PIFR). Therefore, a candidate for a commercial pilot licence, which is a requirement to instruct for the issue of a pilot licence, would need to pass their higher‑level theory exams at an examination centre independent of their FTS.[11]

The registrar, invigilator and candidate each have their own unique password, which limits their access within the system to their specific functions. CASA records access and usage of the PEXO system and provides an e-learning module for the system users (registrars, invigilators and candidates). They also undertake surveillance of examination centres, which may, or may not, be conducted with advance notice. 

The exams are accessed by connection to the CASA server during an examination. When an exam is started, the questions and associated answers will be generated from a database of questions, and a timer will count down. The program will automatically close the exam when the time has expired or if the candidate selects ‘End’ exam and ‘logout’. After the candidate selects ‘End’ exam, it will be automatically submitted for marking and the result recorded against the candidate. The invigilator login is needed to recover the result and the associated knowledge deficiency report for the candidate. 

Granting of a Recreational Pilot Licence

Under CASR Part 61.480, CASA can grant an RPL to an individual on the basis of them holding a pilot certificate, granted from certain organisations, which included RAAus. In this scenario, the applicant is taken to have passed the aeronautical knowledge examination and flight test for the licence and associated aircraft category rating issued.

The applicant is also taken to have met the requirements for the aircraft class rating and design feature endorsements for which the applicant is permitted by their pilot certificate to act as the pilot in command. However, they must successfully complete a flight review for their class rating in order to exercise the privileges of their rating. In the case of the accident pilot, this was a single-engine aeroplane class rating.

Mandatory reporting and enforcement process

Background 

Under CASR Part 149.425, RAAus have mandatory reporting requirements to CASA Sport in accordance with their Exposition and the circumstances prescribed by 149.425. If RAAus reported to CASA Sport that they had revoked or suspended a member’s qualification(s), then the matter could be referred by CASA Sport to the CASA Coordinated Enforcement Process (CEP), which is described in the CASA Enforcement Manual.

Under the CEP, the matter is referred to the Coordinated Enforcement Meeting (CEM) where it is allocated to an investigator to investigate and provide a report to the CEM for discussion on whether to proceed with action. The participants in the CEM have a range of options, which include, but are not limited to, the following:

• no action
• education
• counselling
• direct the person to undertake examinations
• suspend authorisations pending completion of a practical or theoretical examination
• varying, suspending or revoking a licence, endorsement or rating.   

Response to RAAus safety related suspension notices 

On 19 December 2024, RAAus issued an SRS notice to all RPC graduates from AFT who did not hold a CASA PPL(A) licence or higher. The notice explanation included the following:

RAAus has identified non-compliance with respect to the conduct and supervision of exams conducted by students at Adventure Flight Training. Based on the evidence available, RAAus is unable to verify that all former students of Adventure Flight Training met the required theoretical knowledge standards required for the issue of a Recreational Pilot Certificate with RAAus. 

Due to the potential for this finding to result in a risk to aviation safety, RAAus has implemented a safety related suspension (SRS) on your Recreational Pilot Certificate (RPC), effective immediately, pending the conduct of an assessment to confirm that your theoretical knowledge meets the expected standard required to maintain an RPC.

On 20 December, RAAus notified CASA Sport of the implementation of the SRS following their ongoing investigation into how AFT was being managed. Their notification to CASA did not include the names of the affected members, but did include the following explanation:

It has been identified that some students undertook RAAus exams using an online system from their home address without the supervision of an instructor. Further, it has been identified that the system used to sit exams online allowed the student to update incorrect answers and resubmit the exam to achieve a successful pass mark.

The process for the affected members to remove their SRS included passing the RAAus converting pilot exam (a requirement for a pilot licence holder applying for an RAAus RPC) under the supervision of an FTS CFI or senior instructor. The exam supervisor also had the discretion to require additional theoretical assessments and one of the AFT instructors subject to the SRS reported to the ATSB that in addition to the converting pilot exam, they were also required to complete the RAAus instructor exam. The instructor also reported to the ATSB that they held a CASA-issued RPL (issued in recognition of their RPC) but CASA had not contacted them about continued exercising of the privileges of their CASA-issued licence.

CASA reported that they recorded all information provided by RAAus in their records management system but no follow‑up was conducted with RAAus to identify the specific members affected. RAAus reported that they elected to voluntarily provide the initial SRS (August 2024) about the AFT CFI to CASA as it involved a higher approval holder. When the AFT graduates’ SRS was implemented in December, RAAus considered that it would be prudent to notify CASA due to the number of pilot certificate holders involved.  

The ATSB obtained a list of the affected members from RAAus, about 7 months after the SRSs were issued, and requested CASA review it against their RPL records. It was identified that 3 affected members held a CASA-issued RPL, granted based on their RAAus RPC, which included 2 at the time the SRS was issued.

Two of those 3 members addressed the SRS within a month of its issue. The third had not addressed it and their RAAus membership had lapsed, which meant that they continued to hold a CASA RPL without restrictions, while their RPC was suspended and would not be lifted unless they re-activated their membership. 

Safety analysis

Introduction

On 16 November 2024, an amateur-built experimental certificate Morgan Cougar Mk 1 aircraft, registered VH-LDV, with a pilot and 2 passengers on board, departed from West Sale Airport, Victoria, for a local area flight. The aircraft collided with terrain in a paddock 19 km north-north-west of West Sale Airport about 17 minutes after departure and shortly after commencing a series of orbits. The aircraft was destroyed and the 3 occupants fatally injured. 

This analysis will discuss the factors that contributed to the accident sequence, including the loss of control and the pilot’s knowledge deficiencies and history of risky flying behaviour. It will also discuss the management of the Adventure Flight Training (AFT) school and the Recreational Aviation Australia (RAAus) examination system. 

In addition, the analysis will examine the aircraft’s occupant restraints, aircraft design and guidance material from the Civil Aviation Safety Authority (CASA) advisory circular for amateur-built experimental certificate aircraft and transition training guidance for buyers of these aircraft. Finally, it will discuss the CASA Sport and Recreation Aviation Branch management of suspension notices received from RAAus.

Accident sequence

Loss of control

Analysis of the final 3 minutes of the flightpath revealed the aircraft’s speed and height were decreasing as it flew a series of turns and orbits. When the aircraft commenced the final turn, the groundspeed and height above the ground had reduced from 103 kt and 716 ft, to 64 kt and 269 ft. Using the recorded local mean and gust wind, the estimated calibrated airspeed was in the region of 67–74 kt at the start of the final turn. The groundspeed reduced to 56 kt during the final turn as the turn radius tightened and analysis of this turn indicated a steep turn with an average 45° angle of bank required for the observed flight path.

A closed-circuit television camera at a nearby farm recorded the aircraft enter the final turn with an angle of bank consistent with a steep turn manoeuvre. The aircraft then pitched nose down at an estimated airspeed of 59–65 kt and height of about 220 ft. Witnesses reported that the aircraft appeared to fall from the sky, and the recorded data indicated an abrupt reduction in altitude and increase in speed. The witness accounts, recorded data, and camera footage were consistent with a loss of control due to an aerodynamic stall.

Wreckage examination found the aircraft attitude was recovering towards straight and level just prior to impact and that the engine was operating at impact. This indicated that it was very unlikely that a mechanical fault contributed to the accident. The amount of engine power at impact could not be determined and the ATSB could not rule out the possibility that the pilot retarded the power lever towards idle in response to the loss of control, which would be the expected response to a nose-low unusual attitude.

The final turn started 7 seconds prior to the stall, at which time the aircraft was estimated to be 29–36 kt above the flight test recorded stall speed of 38 kt in straight and level flight. For a stall to occur in 7 seconds after starting the turn, it required a closure rate of 4–5 kt per second to the stall speed, which was consistent with an accelerated stall at a load factor of 2.5–3G. 

The ATSB could not determine the stall warning system settings, or if an audible stall warning would have been activated prior to the stall event. However, the stall occurred in a steep turn at a height that was insufficient for recovery.

Knowledge deficiencies

Shortly after the accident, the ATSB was contacted by an AFT instructor who was a colleague of the accident pilot. They advised being unaware of the effect of angle of bank and load factor on stall speed. The accident pilot was trained at the same flight training school (FTS) as the reporting pilot for their recreational pilot certificate (RPC) and instructor rating, prompting an examination of the accident pilot’s knowledge of aerodynamics. 

On review of the accident pilot’s last RAAus exam, the ATSB found that they failed the exam on 2 consecutive attempts. On the pilot’s second attempt, the incorrect answers included 2 questions about stalling, one of which included the relationship between angle of bank, load factor and stall speed. While the pilot’s answer had the correct stall speed for the nominated angle of bank, they had the incorrect load factor. However, it is the load factor generated by manoeuvring flight that affects the stall speed and not the angle of bank. Therefore, the pilot was missing the critical link in the relationship – how the load factor is derived from the angle of bank in a level turn, and how the stall speed is derived from that load factor.

The pilot’s incorrect answers resulted in RAAus expressing their concern about the pilot’s knowledge of aerodynamic stalling when they notified the AFT chief flying instructor (CFI) of the result. The question about load factor and stall speed in a turn was listed in the RAAus syllabus of flight as an item that required a thorough understanding at the RPC level and the exam had been submitted for the pilot’s upgrade from instructor to senior instructor. As the pilot had failed this exam twice, a new exam was required to be completed, and the pilot started a CASA commercial pilot licence theory course. 

From early June to early July 2024, the pilot conducted flight training in a Pitts Special aerobatic aircraft. Several parties reported to the ATSB that this was for the purpose of an aerobatics endorsement. The syllabus for an aerobatics endorsement included the effect of load factor on stall speed. However, the flight training records indicated it was transition training and not training for an aerobatics endorsement. While an aerobatics endorsement included a list of underpinning knowledge requirements, which included the relationship between load factor and stall speed, it was not required to be taught for transition training.

In late July, the pilot failed their first attempt at the CASA commercial pilot licence aerodynamics exam, which included an incorrect answer to the effect of manoeuvring on stall speed. This indicated the pilot’s previous misunderstanding of this topic had not been corrected. However, only the knowledge deficiency reports were retrievable by CASA and not the exam questions and answers, which limited the analysis of these exams. A comparison of the 2 subjects the pilot completed revealed they achieved a high pass result for aircraft general knowledge, but a fail result followed by a low pass result for aerodynamics. This indicated that the pilot found learning the aerodynamic aspects of flight challenging, which was consistent with the concerns previously expressed by RAAus.

The RAAus syllabus for an instructor included demonstrating a stall entry at greater than 1G (critical angle of attack is exceeded at a higher airspeed), which could have addressed the misunderstandings that the pilot held from their RPC theory. While the AFT CFI reported that this training was conducted, the 2 AFT instructors interviewed by the ATSB reported that it was not done and the ATSB found no comments in any of the AFT instructor training records to indicate that it was completed. Therefore, the ATSB concluded that it likely was not done and that the pilot’s knowledge of the relationship between load factor and stall speed was likely deficient at the time of the accident, which contributed to them manoeuvring the aircraft close to the stall speed. 

Pilot flying history and aircraft characteristics

The ATSB interviewed several pilots from AFT who were either colleagues of the accident pilot (fellow instructors) or were RPC graduates from the FTS. They all had experience flying with the accident pilot and 2 of them were syndicate members with the pilot in the purchase of the accident aircraft. One of the syndicate members reported they did not experience any risky flying practices with the pilot but was aware that the pilot had received counselling for such flying.

The ATSB identified that several people, including pilots, fellow instructors and CFIs had been counselling the pilot leading up to the accident, including 3 counselling sessions in the 2 months prior to the accident.

In between the counselling sessions in the last 2 months, there were 3 reported instances of risky flying activities by the pilot. It was therefore likely that no individual involved in counselling the pilot had full knowledge of their behaviour and the counselling sessions did not achieve their intended purpose.

While the safety concerns were discussed with the pilot, no reports were submitted to RAAus and therefore no official action was ever taken. It is possible that there was a reluctance to submit official reports after providing counselling, as this action could make the reporter identifiable and result in a loss of trust between the reporter and their community.  

Two fellow AFT instructors each had experiences with the pilot conducting low level steep turns at high and low speeds and had both advocated to the pilot to manoeuvre their aircraft less aggressively. One of the RPC graduates also experienced the pilot manoeuvring the aircraft aggressively during their pre-RPC check flight in 2023 and conducting a slow speed steep turn overhead a tractor during a private flight in November 2024, 15 days prior to the accident. These reports related to RAAus Topaz and Jabiru aircraft, which both had higher published stall speeds than the Morgan Cougar aircraft. This likely led to an expectation by the pilot that similar manoeuvres could be safely conducted in the Morgan Cougar.

The Morgan Cougar was an amateur-built experimental certificate aircraft, which was subject to a 40-hour flight testing period that included stall testing. However, the stall testing was predominantly limited to 1G clean and configured stalls. The builder was able to recollect one instance of a left turn stall at 30° angle of bank. In this case, the aircraft stalled in a sudden and unexpected manner compared with the 1G stall response, and the builder hypothesised that a stall at a greater angle of bank could exaggerate this effect.

The description provided by the builder was consistent with the warning from the United States (US) Federal Aviation Administration (FAA) that there are no rules for the stall behaviour of an experimental aircraft, and that they can depart controlled flight dramatically without any perceptible warning.

The designer of the Morgan Cougar recommended the builder not attempt accelerated stall testing alone, and this was not done, so the responsiveness of the aircraft to this scenario was unknown. However, the accident pilot invited an AFT RPC graduate for a familiarisation flight in the Morgan Cougar 3 days prior to the accident flight, which the passenger described to the ATSB as for the purpose of demonstrating the responsiveness of the aircraft. During the flight, the pilot demonstrated manoeuvring the aircraft at 70–75° angle of bank, which the passenger described as ‘knife-edge stuff’ and would have required a load factor in the region of 3–4G.

According to the FAA, aircraft with light control forces and/or rapid response are susceptible to overcontrolling by pilots who have not received any type-specific training. Furthermore, low wing aircraft tend to roll into the turn during a turning stall. A stall in a turn will increase the height loss during recovery, as the recovery requires a rolling motion followed by a pitching motion, and therefore, the further the aircraft has to be rolled to restore wings level flight, the greater the height loss.

The syndicate members signed the sale agreement on 5 November, 11 days prior to the accident. However, the builder was unable to accompany them on any familiarisation flights and did not discuss the turning stall behaviour of the aircraft with them. Furthermore, it was concluded from interviews and review of ADS-B data that none of the members had completed any transition training on the aircraft. Therefore, it was very unlikely that the pilot was aware of the specific response of the aircraft in a turning and/or accelerated stall scenario, which was very likely different to the 1G stall and different to the approach to stall and post-stall response of aircraft the pilot had delivered RPC training in at AFT. 

Adventure Flight Training school management

Demonstration of stall at greater than 1G

The RAAus instructor syllabus module for aerodynamic stalling included a stall entry at greater than 1G sequence. This was for the instructor candidate to demonstrate exceeding the aircraft’s critical angle of attack at a higher speed than the 1G stall speed. While this was not part of the RPC syllabus, the instructor syllabus required the demonstration to be performed by the instructor to a high degree of accuracy. However, the AFT instructors interviewed by the ATSB reported that this manoeuvre was not taught on their instructor course and their training records did not include any instructor comments to indicate that it had been completed.

The AFT CFI reported that the stall entry at greater than 1G was taught as a turning stall manoeuvre but could not recall any of the performance parameters for it. Furthermore, the AFT records indicated that a competency code was routinely assigned to their RPC candidates for this manoeuvre as part of their stalling training. Once again, there were no comments within the instructor remarks to indicate that it was taught to those members who had a competency code assigned.

Based on this evidence, the ATSB concluded that this competency was likely not taught at AFT and that the competency code was probably misunderstood.

Instructor supervision

Within the RAAus FTS system, instructors required direct supervision from either their CFI or an approved senior instructor. The purpose of this was to provide continuing mentoring and development of the FTS instructors. The level of supervision could be reduced to indirect (remote) for a senior instructor. However, except for the CFI, none of the AFT instructional staff had progressed to senior instructor. The accident pilot attempted to upgrade to senior instructor in early 2024 but failed the required theory exam component.

When RAAus communicated the pilot’s exam result to the AFT CFI on 29 February 2024, they included their concern about the pilot’s knowledge of aerodynamic stalling and the requirement that the pilot remain under direct supervision. However, the AFT instructors reported to the ATSB that their CFI left the FTS for a trip around Australia in early 2024, with occasional return visits. This was supported by another CFI who had been asked, but declined, to supervise the FTS by the AFT CFI in their absence.

RAAus reported to the ATSB that they were not aware of the AFT CFI’s extended absence from their FTS.

Consequently, the AFT instructors were not under direct supervision for the majority of 2024, even though they had all only received their instructor ratings in 2023. Of note, the instructor who had qualified first, in early 2023, reported to the ATSB that they were all relatively inexperienced as instructors and they did not always conduct a check flight with the CFI during their return visits. This was supported by the accident pilot’s logbook, in which there were no check flights with the AFT CFI recorded in 2024. The fact that the AFT CFI had asked an external CFI to supervise the FTS indicated they were aware of their supervision requirements but ultimately did not comply with them.

Pre-flight video briefings

The RPC graduates from AFT Moama in 2023 and 2024 reported that they did not receive any classroom tutorials or in-person pre-flight briefs. Instead, they had to pay a subscription fee to access a series of flight training videos in which the CFI demonstrated the manoeuvres to be flown for each element of the RPC syllabus. While the CFI stated that the videos were not the pre-flight briefing, the AFT instructors reported that they represented the entirety of the pre-flight briefing, with no in-person pre-flight briefs delivered. 

The use of this medium was not prohibited by the RAAus Exposition, but RAAus had not reviewed the material and therefore had no knowledge of the adequacy of instruction presented. Two RAAus CFIs who had reviewed the videos reported that the quality of instruction in these videos was inadequate as the sole source of pre-flight briefing material.

Within the video sequence for stalling, the AFT CFI demonstrated large rudder inputs near the stall speed and instructed the use of the rudder to level the attitude if a wing drop occurred. The risk of inducing a spin, as described in the CASA flight instructor manual for aeroplanes, was not acknowledged.

Additionally, during the stall demonstrations, the CFI omitted flap limiting speeds for the configured stall and did not demonstrate post-loss of control checks to confirm there was no overspeed or overstress of the flap. If flap is subjected to damage from an overspeed or overstress, further damage and control problems can occur if an attempt is made to retract the flap. In the case of an aircraft with a retractable landing gear, the landing gear could become stuck if an attempt to retract it is made after overspeed damage has occurred.

The stalling video also revealed incorrect terminology by the CFI for their explanation of the effect of lowering flap. This related to the basic lift formula, which should have been taught and reinforced throughout the syllabus. 

While all these discrepancies may have been low risk in the demonstration aircraft, they introduced the potential for negative learning[12] in the lesson, which could be later applied in other aircraft types. The report from one of the AFT instructors, that they believed the accident pilot had copied the CFI in performing dumbbell reversal turns upwind in the circuit to expedite practice landings with students, indicated that negative learning was likely occurring at AFT. 

A component of the instructor assessment was the in-person delivery of a pre-flight brief and post-flight debrief. However, this was not practiced by the staff at Moama after they passed their instructor rating because of the use of pre-flight video. The Moama RPC graduates reported that the lack of access to in-person tutorials and pre-flight briefs contributed to learning difficulties for their flight training and theory exams. The delivery of pre-flight briefs is also important for instructor development because the practice requires them to explain how the theory of flight will be applied in the lesson, check their student’s knowledge, and answer impromptu questions about the topic. It is also the time to discuss any hazards associated with the flight and ensure the student and instructor have a shared understanding of how the lesson will be conducted.

The report from one of the instructors after the accident that they were not aware of the relationship between angle of bank, load factor and stall speed, which is part of the RPC syllabus, may have been the result of knowledge decay because they were not required to deliver briefings. The substitution of video briefs for in-person pre-flight briefs was likely at the expense of both student and instructor development.

Online exams

The AFT CFI introduced an online exam platform used at the Moama Airfield school, for which their students and staff were provided with a login. The ATSB discussed the use of online exams with an instructor and RPC graduate who completed their exams at Riddell Airfield, and they both reported they followed the RAAus paper-based exam process and had no knowledge of the online platform.

The RPC graduates from Moama were prompted by the CFI or staff when they needed to complete a theory exam, which was done online and without supervision. The CFI setup the exams so that 2 attempts could be made and the correct answers to all questions were revealed in the exam report after the first attempt. Consequently, one of the graduates who failed the basic aeronautical knowledge exam on their first attempt photographed all the questions with the correct answers identified and passed the exam on their second attempt. More generally, the online exam setup likely created an attitude from the staff at AFT that candidates would naturally pass the exam on a second attempt if needed. Significantly, there were no failure results from 146 exams in the AFT exam records over a 3-year period.

The accident pilot’s first attempt at the RAAus private pilot licence (aeroplane) (PPL(A)) equivalent exam was completed using the AFT online platform. The software provider had informed the CFI that answer ‘A’ was set as the default correct answer to all questions as they were not provided with the marking rubric. The pilot had used this platform previously for their instructor exam in May 2023 and, given that the other instructor from Moama was aware of how the system was setup, it was very likely that the pilot was also aware of the settings. Consequently, the pilot’s selection of answer ‘A’ to 47/50 questions, the majority of which were technically incorrect, indicated that they were answering to the marking system and not the questions. 

The pilot’s selection of answers may have resulted from the exam report providing the correct answers after a failed first attempt or from the CFI informing the pilot of the default correct response. In either case, the CFI reported that as the administrator, they were the only person who could download a copy of the exam. Therefore, they would have known the result for the exam they submitted to RAAus was almost certainly incorrect based on the default marking. 

Recreational Aviation Australia examination system

The RAAus Exposition, approved by CASA under CASR Part 149, provided a basic overview of their examination system. Multiple-choice exams were provided and the FTSs were to store them securely and not reproduce or distribute them. The exams were distributed to the FTSs via email after each respective CFI had signed a declaration that the exams would be stored securely and not be reproduced or distributed. Candidates for theory exams were provided with an exam answer sheet on which they recorded their answer to each question. All exams were required to be supervised, marked, debriefed and the results recorded and retained by the FTS, with the exception that the RAAus PPL(A)-equivalent exam was to be marked by RAAus. There was no documented exam failure management process.

The RAAus instructor application form indicated that the upgrade to senior instructor was the only time that proof of successful exam completion was required to be provided, which was a change introduced in 2023. Prior to 2023, RAAus did not require proof of completion of any exams for the issue of a qualification or endorsement. In each case they accepted the certification from the examiner that the theory component was met. However, this did not necessarily confirm the examiner had sighted the exam and their certification could be based on the record of result provided by the FTS. The RAAus Exposition required the FTSs to be able to provide exam results on request and RAAus reported that it was the record of exam results that they inspected at audit and not the exam answer sheets. 

Consequently, the AFT CFI was able to progress through their instructor and senior instructor upgrade to CFI approval and the establishment of the AFT FTS, all without providing proof to RAAus that they had completed the associated theory exams. After the FTS was established, the CFI setup a system for online exams that could be completed by AFT members as open-book assessments without supervision. Further, all correct answers were revealed after the first attempt, and the exam could be immediately retaken. This non-compliant system likely existed throughout 2023, unnoticed by RAAus, as AFT’s use of an online platform only came to their attention in January 2024. The accident pilot had used the platform for their instructor exam in May 2023, but proof of completion of the instructor exam was not required to be provided to RAAus. 

The CFI’s upgrade to senior instructor was investigated by RAAus in early 2024 after they discovered the accident pilot’s PPL(A)-equivalent exam failure. They were unable to confirm with the examiner for the CFI’s senior instructor upgrade that the associated exam was done. The setup of the AFT online exam system, and the CFI’s subsequent submission of an exam and certification of remote supervision by a former instructor 2 days after the exam was submitted, all suggested a cultural malaise towards the theory examination requirements. 

The ATSB’s review of the RAAus examination system and the situation that unfolded at AFT, indicated that the only risk control evident in the theory examination system was the CFI declaration to not reproduce or distribute exams. The only effective oversight of exams by RAAus was the marking of the PPL(A)-equivalent exam, as the other oversight activities appeared to be limited to the records of exam results. 

The situation at RAAus contrasted with the CASA examination system, which had multiple controls in place for the access to and conduct of exams, supported by surveillance of the examination centres, which could be unannounced. CASA also had restrictions in place for the exams that could be hosted by an FTS, such that a candidate for an instructor rating would have to conduct some of their theory exams at an examination centre independent of their FTS. 

In 2025, there were a significant number of RAAus FTSs and members, estimated at 160 and 10,000+ respectively based on information from their website. This presented a significant risk management challenge for the integrity of their pilot examination system, particularly noting that their pilots could use their RPC to obtain a CASA licence. Considering the size and complexity of their operation, and what unfolded at AFT as described previously, the ATSB concluded that the RAAus examination system, as described in their Exposition, did not include sufficient controls to prevent the system from being exploited.

Restraint failure

The front seat occupants were ejected from their seats in the accident and the ATSB found the seatbelt latch plates separated from their buckles. However, no evidence was found to indicate the seatbelts were susceptible to false latching, and they were subjected to load testing by the builder. Other mechanisms by which a car seatbelt can fail to perform its function include inadvertent unlatching from occupant flailing in an accident and inertial unlatching. Inertial unlatching is a known phenomenon with car seatbelts in rollover accidents, when they are subjected to vertical accelerations.

The CASA advisory circular guidance for amateur-built experimental certificate aircraft (AC 21.4(2)) recommended that seatbelts comply with the US FAA Technical Standard Order approval for seatbelts. However, the builder did not believe they complied with the recommended standard and that the design was consistent with car seatbelts.

The ATSB reviewed pre-accident photographs of the interior of the aircraft and found the design of the seatbelts was consistent with car seatbelts and inconsistent with aircraft seatbelts. While the release of the front seatbelts would have contributed to the injuries sustained by the front seat occupants, the fatal injuries were likely the result of the ground impact.

Aircraft design and guidance

Energy attenuation

The pathologist reported that all occupants experienced non-survivable, blunt-force trauma injuries. However, the front seat occupants had a common vertebral crushing injury that was not found on the rear seat occupant. A likely source of the discrepancy between the front and rear seat occupant injuries was the location of the front seats above the main wing spar, as per the original design.

There are different mechanisms in which energy attenuation can be incorporated into design, but light aircraft are generally limited to the landing gear and seating. Poorly designed seats can produce spinal fractures in ground impacts as low as 8–10 G. In this situation, an unyielding structure, such as a main wing spar, can transmit a force to the occupant of the seat in excess of the ground impact force and the occupant will suffer injuries greater than those expected from the impact. 

Neither the landing gear nor seating of the accident aircraft appeared to include consideration of crashworthiness in the design. The landing gear separated at impact and did not incorporate any stroking mechanism to absorb vertical energy, and the seating did not incorporate energy attenuation into the design. These 2 design deficiencies contributed to the severity of injuries to the occupants. However, the injuries indicated a minimum force experienced by the occupants and not the actual force they experienced. Therefore, it could not be concluded if a design change would have reduced the forces experienced to a survivable level. Despite that, the ATSB noted that similar accident scenarios in type-certified aircraft have been survivable.

Energy attenuating seat designs, such as stroking mechanisms, deforming box structures and rate-sensitive seat bottom cushions can all play a role in reducing the lumbar load experienced by the occupant in an accident. While there is no requirement for amateur-built aircraft to address this issue, it may be feasible for energy absorbing features to be incorporated into the design of some aircraft. 

The CASA advisory circular guidance for amateur-built experimental certificate aircraft (AC 21.4(2)) recommended the delethalization of the cockpit and installing approved seatbelts but was silent on the issue of energy attenuation for the landing gear and seating. However, a 2013 ATSB aviation research report on amateur-built aircraft accidents found they resulted in a higher rate of fatal and serious injuries than factory‑built and certified aircraft. This indicated that the amateur-built industry could benefit from additional guidance in this area. However, as the CASA AC is guidance material and the recommendations may not be practicable for all builders to implement, it has not been raised as a safety issue. 

Crashworthiness of the fuel system

The pathologist’s examination of the pilot indicated they were deceased prior to the post‑crash fire. However, the wreckage examination revealed a near total destruction of the cabin area by fire, while the extremities of the aircraft were relatively undamaged by fire. This was despite the collision occurring in a relatively level attitude in an open paddock with no penetrating objects. 

The main fuel tank was carrying the flight fuel, and it was installed between the instrument panel and the engine firewall, as designed. This made it susceptible to rupturing in a collision and spraying fuel over the engine and occupants, which occurred in the accident. However, the wing fuel tanks installed aft of the main spar, which were a builder modification, were found intact and provided greater separation of the fuel load from the engine and occupants than the main tank. 

The susceptibility of fuel tanks to rupturing in an accident is not new and there have been published recommended design standards to address this for light aircraft since at least 1980 (Johnson et al. 1980 and 1989). They included guidance for the location of fuel tanks, which should consider the location of occupants, ignition sources and probable impact areas. They recommended fuel tanks be located such that as much aircraft structure as possible can crush before the tanks are exposed to direct contact with obstructions.  

The CASA advisory circular guidance for amateur-built experimental certificate aircraft (AC 21.4(2)) recommended reducing the risk of fire hazard. However, the specific design recommendations were limited to the inclusion of a fireproof firewall between the engine compartment and the cabin. It did not recommend or discuss how to incorporate crashworthiness into the design of the fuel system, and specifically the considerations for the location of fuel tanks. 

Given the susceptibility of aircraft fuel tanks to rupturing and the detrimental effect that it can have on post-crash survival, the ATSB concluded that the amateur-built industry could benefit from additional guidance in this area. However, as discussed previously, the CASA AC for amateur-built experimental certificate aircraft is guidance material and the recommendations may not be practicable for all builders to implement. Therefore, it has not been raised as a safety issue.

Transition training guidance

The accident pilot was a member of a syndicate of 3 pilots who purchased the aircraft on 5 November 2024, 11 days before the accident. While the pilot and another member of the syndicate held instructor ratings, they were for RAAus-registered aircraft, which were 2‑seat aircraft with a maximum take‑off weight of 600 kg. The accident aircraft was a 4‑seat amateur-built experimental certificate aircraft on the CASA register with a maximum take‑off weight of 800 kg.

None of the syndicate pilots were qualified to instruct on this aircraft and none of them met the minimum licence requirements to conduct Phase 1 flight testing, which required a PPL(A) as a minimum. However, they could pilot the aircraft with an RPL as the Phase 1 flight testing of the aircraft was completed by the builder before they purchased it.

In the 11 days after the syndicate purchased the aircraft, ADS-B data recorded 7.7 hours of flying, the majority of which were ferry flights. While the accident pilot likely did most of the flying in the aircraft, the other syndicate members reported that it was unlikely that any aerial work training flights were conducted. One of the syndicate members was concerned about the weight and balance of the aircraft and they had agreed not to conduct any verification flights before the aircraft could be reweighed, which occurred 2 days prior to the accident. In addition, the builder had not conducted any familiarisation flights with them and had not recommended any aerial work exercises for them. Therefore, the ATSB concluded that the pilot had not received any transition training in the aircraft.

A 2013 ATSB aviation research report on amateur-built aircraft accidents found the pilots involved in accidents were significantly more experienced overall than factory-built aircraft accident pilots. However, they were significantly less experienced on the aircraft type that they were flying at the time of the accident, and a quarter of the accidents were from loss of control. 

Previously, in 2012, the US National Transportation Safety Board published a report, which found that pilots who did not seek training for their experimental amateur-built aircraft were overrepresented in accidents. They reported that accidents involving loss of control could be reduced with transition training, which led to a recommendation to the FAA to develop resources for transition training and encourage builders and new owners to complete the training.

The FAA published AC 90-109(A) Transition to unfamiliar aircraft, in 2015. The AC stated that ‘accidents resulting from loss of aircraft control or situational awareness frequently result from pilot unpreparedness for challenges presented by the aircraft’ and provided recommendations for training experience based on aircraft performance and handling characteristics. The AC included an extensive discussion about the variety of stall characteristics that amateur-built aircraft can exhibit and recommended stall avoidance and recovery training from a qualified instructor. 

The FAA AC included a ‘Best Training’ recommendation, which is accomplished in the specific aircraft the pilot intends to fly with a qualified instructor who has recent experience in the same make and model. The accident pilot had previously conducted transition training on the Pitts Special aircraft with an instructor who also had experience with the Morgan Cougar Mk 1 aircraft. Therefore, the ‘best training’ model recommended by the FAA in their AC was an option the syndicate could have pursued.

The CASA advisory circular guidance for amateur-built experimental certificate aircraft (AC 21.4(2)), included recommended safety precautions for the flight-testing phase, which emphasised a graduated process. The purpose of this was for the pilot to learn the behaviour of the aircraft near the centre of the flight envelope before pushing the aircraft out towards the predicted boundary of the envelope. As stated in the AC, ‘Violent or aerobatic manoeuvres should not be attempted until sufficient flight experience has been gained to establish that the aircraft is satisfactorily controllable throughout its normal range of speeds and manoeuvres.’ Despite these recommended precautions for pilots in the flight-testing phase, there were no recommendations for new owners to seek transition training or for sellers to recommend buyers conduct transition training.

The recommended precautionary approach to the flight testing in Phase 1 could equally apply to a new owner of an amateur-built experimental certificate aircraft. Therefore, the ATSB concluded that the amateur-built industry could benefit from further guidance in this area. However, the CASA AC for amateur-built experimental certificate aircraft is guidance material, which may not be practicable to follow in all circumstances, such as a single-seat unique design aircraft. Therefore, it has not been raised as a safety issue.

Civil Aviation Safety Authority management of suspension notices

An individual must be a member of RAAus to exercise the privileges of their RPC. Pilots can then use their RPC, issued by RAAus, to obtain a CASA-issued RPL without completing either a CASA pilot exam or flight test, although a CASA flight review was required to exercise the privileges of the RPL. RAAus is an approved self-administering aviation organisation under Civil Aviation Safety Regulation (CASR) 149, which imposes reporting requirements to CASA under CASR 149.425. The reporting line is from RAAus to the CASA Sport and Recreation Aviation Branch (CASA Sport).

The RAAus mandatory reporting requirements to CASA are detailed in their Exposition, specifically in their occurrence and complaints handling manual (OCHM) under the Formal Inquiry process. However, the RAAus Exposition has a safety related suspension (SRS) notice as a risk management tool within the Informal Assessment process. As the SRS sits within the Informal Assessment process, and is not enforcement action, it does not require notification to CASA. However, RAAus, at their own discretion, can notify CASA that they have issued an SRS where they believe the circumstances warrant such notification. 

In August 2024, RAAus elected to notify CASA of the SRS issued against the AFT CFI because of the position the person held within RAAus. In December 2024, they notified CASA that an SRS was issued against the graduates of AFT because of the number of pilot certificate holders involved. However, the accident pilot had never been issued with an SRS despite their previous exam failures and flying history, and therefore, there was never any cause for CASA to receive a notification about the pilot.

On receipt of the RAAus AFT SRS notifications, CASA Sport entered the details into the CASA records management system, but no further action was taken. CASA had a process for follow-up of notifications, which was their Coordinated Enforcement Process (CEP), detailed in their enforcement manual. Within the CEP an investigator could be appointed to make preliminary enquiries and report findings to the Coordinated Enforcement Meeting for consideration. 

After the ATSB received the details of the persons affected by the SRS issued to the graduates of AFT and their CASA licence status, it was found that 2 members also held RPLs at the time their SRSs were issued. In both cases, their RPL was granted based on their RPC which was subsequently suspended by the SRS. The ATSB spoke to one of those individuals, who reported that nobody from CASA had contacted them, but they had acted immediately to complete the remedial actions to have their SRS lifted. However, the second individual’s membership with RAAus had lapsed and they had not had their SRS lifted when the ATSB received the list of affected persons about 7 months after the SRSs were issued. RAAus confirmed that in this case the individual’s membership profile is flagged to address the remedial action if they re-activate their membership and that there were no continuing reporting requirements to CASA beyond the initial notification.

Consequently, an individual could continue to exercise the privileges of a licence issued by CASA based on holding an RPC while their RPC was suspended. This revealed a missing link within CASA’s internal process for handling the notification of an SRS, with no mechanism in place to ensure CASA Sport forwarded relevant information from the SRS to the CASA CEP for review.

Findings

From the evidence available, the following findings are made with respect to the loss of control and collision with terrain involving a Morgan Cougar Mk1 aircraft, registered VH‑LDV, 19 km NNW from West Sale Airport, Victoria, on 16 November 2024. 

Contributing factors

• The aircraft entered an accelerated stall in a steep turn with insufficient height to recover, resulting in a collision with terrain.
• It was likely that the pilot had an inadequate understanding of the relationship between angle of bank, load factor and stall speed, which contributed to the pilot not fully understanding the risk of conducting slow steep turns.
• The pilot had a reported history of conducting low flying and slow steep turns and was likely unaware that, while the accelerated stall characteristics of the accident aircraft were unknown, there were indications that it would be abrupt.
• The Adventure Flight Training school management practices did not provide the required level of supervision, training and assurance that their graduates had achieved the required level of aeronautical knowledge and understanding for the qualifications they received. (Safety issue)
• The Recreational Aviation Australia pilot theory examination system did not incorporate sufficient risk controls to ensure that their examination processes were followed as intended and their members had achieved the minimum required knowledge in accordance with the syllabus of flight training. (Safety issue)

Other factors that increased risk

• The pilot was counselled about unsafe flying practices but was not reported to any authority and therefore no official follow-up action was ever initiated.
• The aircraft design did not incorporate energy attenuation in the landing gear and seating and located the fuel tank between the engine firewall and instrument panel, which resulted in a post-crash fire. While these factors increased the severity of the injuries to the occupants, it could not be determined if design changes would have made them non-fatal.
• The aircraft’s front seats were likely fitted with car seatbelts, which unlatched in the accident and resulted in the front seat occupants being ejected from their seats. While this exposed them to additional injuries, the fatal injuries were likely from the aircraft‑ground impact.
• The Civil Aviation Safety Authority guidance material for amateur-built experimental aircraft did not recommend consideration of the crashworthiness of seating and fuel tank installation. These characteristics within the design of the aircraft increased the risk of occupant injuries in an accident.
• The pilot had not conducted transition training and the Civil Aviation Safety Authority guidance material for amateur-built experimental aircraft did not include a recommendation for new owners to receive transition training.
• The Civil Aviation Safety Authority (CASA) Sport and Recreation Aviation Branch did not have a process in place to verify if individuals subject to a suspension from a self-administering organisation held a CASA licence and to ensure the information was provided to the CASA Coordinated Enforcement Process for review. (Safety issue)

Safety issues and actions

Adventure Flight Training school management

Safety issue number: AO-2024-058-SI-01

Safety issue description: The Adventure Flight Training school management practices did not provide the required level of supervision, training and assurance that their graduates had achieved the required level of aeronautical knowledge and understanding for the qualifications they received.

Recreational Aviation Australia examination system

Safety issue number: AO-2024-058-SI-02

Safety issue description: The Recreational Aviation Australia pilot theory examination system did not incorporate sufficient risk controls to ensure that their examination processes were followed as intended and their members had achieved the minimum required knowledge in accordance with the syllabus of flight training.

Civil Aviation Safety Authority management of suspension notices

Safety issue number: AO-2024-058-SI-03

Safety issue description: The Civil Aviation Safety Authority (CASA) Sport and Recreation Aviation Branch did not have a process in place to verify if individuals subject to a suspension from a self‑administering organisation held a CASA licence and to ensure the information was provided to the CASA Coordinated Enforcement Process for review.

Safety action not associated with an identified safety issue

Additional safety action by Recreational Aviation Australia

• The draft rewrite of the Recreational Aviation Australia (RAAus) occurrence and complaints handling manual (OCHM) has been updated to include a description of the process for handling a safety related suspension (SRS) for an individual whose membership has lapsed.
• The draft rewrite of the Recreational Aviation Australia (RAAus) syllabus of flight training has been updated to include further development of the stalling element of the syllabus.

Glossary

Sources and submissions

Sources of information

The sources of information during the investigation included:

• accident witnesses
• the aircraft builder
• Airservices Australia
• Bureau of Meteorology
• chief flying instructors from Recreational Aviation Australia
• Civil Aviation Safety Authority
• the former chief flying instructor from Adventure Flight Training
• former instructors and pilot graduates from Adventure Flight Training
• Recreational Aviation Australia
• Victorian Institute of Forensic Medicine
• Victoria Police
• video footage of the accident flight.

References

Australian Transport Safety Bureau (2013) 

(AR-2007-043(2)), accessed 30 May 2025.

Civil Aviation Safety Authority (2000) Amateur-built experimental aircraft – certification (Advisory Circular 21.4(2)), accessed 13 May 2025.

Civil Aviation Safety Authority (2007) Flight instructor manual: aeroplane, accessed 26 March 2025.

Civil Aviation Safety Authority (2022) Experimental certificates (Advisory Circular 21-10 v4.3), accessed 13 May 2025.

Federal Aviation Administration (1986) Static strength substantiation of attachment points for occupant restraint system installations (Advisory Circular 23-4), accessed 24 June 2025.

Federal Aviation Administration (1993) Technical Standard Order: C22g, safety belts (TSO C22g), accessed 24 June 2025.

Federal Aviation Administration (2015) Amateur-built aircraft and ultralight flight testing handbook (Advisory Circular AC 90-89B), accessed 20 May 2025.

Federal Aviation Administration (2015) Transition to unfamiliar aircraft(Advisory Circular 90-109(A)), accessed 3 July 2025.

Society of Automotive Engineers (1986) Aerospace standards: Torso restraint systems (SAE AS 8043), accessed 24 June 2025.

Taylor AM and Moorcroft DM (2023) Seat and occupant response in energy absorbing seats (Civil Aerospace Medical Institute DOT/FAA/AM-23/17), accessed 22 May 2025.

Gratton G (2015) Initial airworthiness: determining the acceptability of new airborne systems, Springer, London.

Johnson NB et al. (1989) Aircraft Crash Survival Design Guide Volume V – Aircraft Postcrash Survival (USAAVSCOM TR 89-D-22E), accessed 3 July 2025.

National Transportation Safety Board (2012) The Safety of Experimental Amateur-Built Aircraft (NTSB/SS-12/01), accessed 28 March 2025.

Payne R and Stech E (1969) Dynamic models of the human body (Aerospace Medical Research Laboratory AMRL-TR-66-157), accessed 3 July 2025.

Roberts et al. (2007) ‘Failure analysis of seat belt buckle inertial release’, Engineering failure analysis, 14(6):1135-1143.

Shanahan DF (28-29 October 2004) Basic Principles of Crashworthiness: Pathological Aspects and Associated Biodynamics in Aircraft Accident Investigation. Madrid, Spain: RTO-EN-HFM-113, accessed 3 July 2025.

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the aircraft builder
• Civil Aviation Safety Authority
• the former chief flying instructor from Adventure Flight Training
• Recreational Aviation Australia. 

Submissions were received from:

• Civil Aviation Safety Authority
• the former chief flying instructor from Adventure Flight Training
• Recreational Aviation Australia. 

The submissions were reviewed and, where considered appropriate, the text of the report was amended accordingly.

Appendices

Appendix A – Examination of the flight controls

Introduction

Examination of the flight control system chainring and bearings included a photographic review of the chainring at the wreckage site and as installed in the aircraft pre-accident, which was behind the instrument panel (Figure 12). 

Figure 12: Location and movement of chainring

Source: ATSB

The part that transmitted roll control from either yoke to the ailerons consisted of 2 chainrings welded together around a hexagonal nut to form one part, hereafter referred to as the ‘chainring’ (Figure 13). The chainring was supported by an inner and outer bearing attached to a support frame. Two grub screws located in threaded holes through the nut were present to secure the chainring to a bearing. 

Figure 13: Front chainring facing pilot (left) and rear chainring facing engine (right)

Source: ATSB

Examination and findings

It was noted that the chainring hexagonal nut appeared to be centrally located on the bearings (Figure 14 left) before the controls were disturbed for onsite examination and that the chainring only separated from the bearings when it was disturbed. Pre- and post‑accident photographs of the flight controls and measurement of the clearance between the chainring and the support frame indicated that the 2 grub screws could only have engaged with the outer bearing (Figure 14 right). 

Figure 14: Location of bolt relative to hexagonal nut (left) and bearings (right)

Source: ATSB

The examination found that the 2 grub screws were not proud of the hexagonal nut inner diameter (Figure 15 [1, 2]) and they had an angular separation of 117° (Figure 15 [3]). The inner bearing and the outer bearing (Figure 15 [4]) were examined, cleaned and re‑examined. No witness marks from the grub screws were identified. The grub screws (Figure 15 [5, 6]) were examined, cleaned and re-examined and no bearing witness marks were identified. Therefore, ATSB examination could not confirm that the grub screws retained the chainring to either bearing.

Figure 15: Condition of grub screws and outer bearing

Source: ATSB

Appendix B – Flight path description

Introduction

The end-of-flight analysis was divided into sections based on the manoeuvring of the aircraft, which have been annotated on the supporting figures. It started with a right turn, followed by a reversal into a left turn followed by 2 full orbits. A third left orbit commenced inside of the second orbit, which led to the stall and collision with terrain. Airservices Australia ADS-B data was used, and altitudes are recorded in 25 ft increments. The last 3 data points, considered unreliable, were inconsistent with the observed CCTV and were potentially predicted points that were not updated prior to the collision.[13] The calibrated airspeed (CAS) range was calculated by the ATSB using a 6 kt mean wind and 12.8 kt wind gust from 124° T recorded at a local weather station 4 km north of the accident site. 

End of flight description

With reference to Figure 16:

• At the start of the right turn (RH turn – yellow) at 1744:17, the aircraft recorded a groundspeed of 98 kt (87‍–‍91 kt CAS) and an altitude of 825 ft (683 ft AGL). Altitude was maintained through the turn, but groundspeed (and estimated CAS) reduced.
• The first orbit (First orbit – blue) started at 75 kt groundspeed (78‍–‍85 kt CAS) and an altitude of 825 ft (689 ft AGL) and the aircraft descended about 250 ft during the orbit.
• The second orbit (Second orbit – orange) started at 82 kt groundspeed (84‍–‍89 kt CAS) and an altitude of 575 ft (442 ft AGL). During the orbit, the aircraft descended and conducted a low pass (Low pass) at 97 kt groundspeed (89‍–‍92 kt CAS) and an altitude of 225 ft (97 ft AGL).
• A brief straight section (cyan) started at 69 kt groundspeed (72‍–‍79 kt CAS) and an altitude of 400 ft (267 ft AGL) and reduced to 64 kt groundspeed (67‍–‍74 kt CAS) at the start of the final turn (Turn – magenta) at 1746:52.
• In the final turn at 1746:59 (Stall), the groundspeed reached a minimum of 56 kt (59‍–‍65 kt CAS) at an altitude of 350 ft (221 ft AGL) as the turn radius tightened and an average of 45° angle of bank was required for this turn radius.
• The last reliable data point was recorded at 1747:02 and indicated a groundspeed of 71 kt (69 kt CAS) at an altitude of 275 ft (143 ft AGL). The abrupt descent and increase in speed were consistent with a conventional stall response.

In the accompanying Figure 17, the start of the right turn (RH turn), start of the first orbit (First orbit), start of the second orbit (Second orbit), low pass (Low pass), start of the final turn (Turn) and stall (Stall) are annotated. The lowest speeds were recorded on the segment from the final turn to the stall, which was also the segment with the smallest turn radius. 

Figure 16: Accident flight path

Source: Airservices Australia, annotated by the ATSB

Figure 17: Plot of ADS-B data and CAS calculations with the start of each orbit

Source: ATSB

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. About ATSB reports ATSB investigation reports are organised with regard to international standards or instruments, as applicable, and with ATSB procedures and guidelines. Reports must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2025   Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the Australian Transport Safety Bureau.  Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

Investigation summary

What happened

On the morning of 22 October 2024, the pilot of a Cessna Aircraft Company 150L, registered VH‑EYU, was conducting a private flight from Bacchus Marsh aircraft landing area, Victoria. Strong and gusting winds were present. After commencing a take-off roll, the pilot rejected the take-off, before taxiing back to the same runway for a second take‑off.

On the second take-off, the aircraft became airborne and climbed to about 150 ft above the runway, before it pitched steeply nose-up, then the nose dropped suddenly, followed by the left wing dropping. The aircraft then entered a vertical descent, rotating approximately 270° before colliding with terrain. The pilot, who was the sole occupant of the aircraft, was fatally injured, and the aircraft was destroyed. 

What the ATSB found

The ATSB found that shortly after take-off, in strong and gusty wind conditions, the aircraft stalled at a height too low to recover before colliding with terrain. It is probable that the aircraft was too slow on take-off into those conditions, and that inputs made to counteract the crosswind increased the angle of attack of the left wing. These factors, combined with the wind conditions, increased the risk of a quick and unrecoverable stall.

Safety message

While an aerodynamic stall can occur at any airspeed, at any altitude, and with any engine power setting, it is most hazardous during take-off and landing when the aircraft is close to the ground. When gusting conditions are present, pilots should consider waiting for more benign conditions. Guidance advises pilots to conduct their own testing in progressively higher winds to determine both their own capability and that of the aircraft. 

Maintaining the aircraft’s attitude and correcting any change in attitude due to wind gusts during climb, is vital to ensure the critical angle of attack is not exceeded. Reducing the angle of attack by lowering the aircraft nose at the first indication of a stall is the most important immediate response for stall avoidance and recovery. 

Pilots must understand and recognise the conditions which make stall more likely and the symptoms of an approaching stall so they can act to prevent a stall before an unrecoverable condition develops. If pilots judge the weather to be suitable, they should consider climbing out at a higher airspeed to provide a buffer above their aircraft’s stall speed for detection and correction of an impending stall. 

The investigation

The occurrence

On the morning of 22 October 2024, at the Bacchus Marsh aircraft landing area (ALA), Victoria, a Cessna Aircraft Company 150L aircraft, registered VH‑EYU, was being prepared for a private flight under visual flight rules[1] to Lethbridge ALA, Victoria, about 35 km to the southwest. The weather conditions at the time were described as having strong, variable and gusty winds with a temperature of about 27°C.

Closed circuit television (CCTV) showed the pilot arriving for their flight at about 1000. Later, at about 1047, another CCTV camera located at a flying school, recorded the aircraft taxiing to the fuel bowser. After fuelling, the pilot drained a fuel sample from the aircraft fuel tanks and checked the sample. The pilot, who was the sole occupant, climbed in, then started the aircraft and taxied to a run‑up area[2] and performed engine run-up and flight control checks. They then taxied toward runway 27[3] for take‑off (Figure 1).

At about 1110 local time, a common traffic advisory frequency[4] (CTAF) recording captured the pilot stating that they were commencing their take‑off roll. Shortly after, the pilot transmitted another radio call stating that they were rejecting the take‑off. There was no further information provided by the pilot to explain why the take‑off was rejected. 

The rejected take-off attracted the attention of witnesses who were now observing VH‑EYU. The pilot taxied the aircraft off the runway and returned to the end of runway 27. At 1114, the pilot commenced a second take‑off roll.

The witnesses included a flight instructor. They identified that the aircraft appeared unstable after take-off. The CCTV showed the right wing dipping twice during this take‑off, with the pilot levelling the aircraft each time. The flight instructor stated that at about 50 ft, the aircraft pitched up quickly, before the nose was pushed down again.

After the aircraft had passed the runway intersection and reached an altitude of about 150 ft, it pitched steeply upward, before the nose and then the left wing rapidly dropped. The aircraft entered a nose down vertical descent to the left, rotating approximately 270° before colliding heavily with terrain. After the collision, personnel from the flying school attended the accident site and found the pilot fatally injured. The aircraft was destroyed. 

Figure 1: Bacchus Marsh ALA and VH‑EYU approximate flight path (yellow) and accident site

Source: Google Earth, annotated by the ATSB

Context

Pilot information

The pilot commenced their flight training in July 2019 and held a recreational pilot licence (aeroplane), which was issued on 14 November 2023. They held a single engine aeroplane class rating. The pilot also held navigation, controlled aerodrome, controlled airspace and flight radio endorsements which were issued on 19 April 2024. 

Overall, the pilot had accumulated about 184 hours total aeronautical experience, of which 71.9 hours were in the Cessna 152 and 3.8 hours in the Cessna 150.

The pilot joined Bacchus Marsh Aero Club on 19 August 2024 and had completed 3 club check flights with an independent instructor during September and October 2024. Since joining the club, the pilot had flown a total of 20.1 hours in Cessna 172, Cessna 152 and Cessna 150 aircraft. They had also flown 3.3 hours in a Cessna 152 the previous day. 

The pilot held a Class 2 aviation medical certificate issued by the Civil Aviation Safety Authority, without medical restrictions, which was valid until 19 March 2026.

Post-mortem examination 

The post-mortem and toxicology examinations did not identify any indication of incapacitation or substances that could have affected the pilot’s capacity to perform the flight.

Aircraft information

The Cessna 150L is a high wing, all-metal, 2‑place, single‑engine aircraft with a fixed tricycle landing gear. It is powered by a 4‑cylinder Teledyne‑Continental O‑200‑A engine, driving a 2‑blade fixed‑pitch propeller. VH‑EYU (Figure 2) was manufactured in the United States in 1974 and first registered in Australia in May 1974. It had been owned by the Bacchus Marsh Aero Club since December 2023. 

The aircraft was fitted with a stall warning horn on the left wing, which produces an audible signal to the pilot when the wing is approaching its critical angle of attack (AoA). The Cessna 150L’s stated stall speed in take‑off configuration with wings level was 48 kt.[5]

No crosswind limitation was published in the C150 L model owner’s manual. There was only a need for the manufacturer to demonstrate crosswind capability up to 8.5 kt (20% of the stall speed in a landing configuration). While it is possible that the aircraft may be capable of meeting the controllability standard in higher winds, this had not been established by the manufacturer.

Figure 2: VH-EYU

Source: Bacchus Marsh Aero Club

Recent maintenance history

The last 100‑hour periodic maintenance inspection was conducted on 19 January 2024. At the time of the accident, VH‑EYU had accrued a total time in service of 8,962.3 hours. Maintenance records also showed that since January, the following maintenance had been performed:

• a 50-hour/6-month oil and filter change
• the left brake was serviced
• the flap position indicator spring was replaced.

The aircraft had flown about 36.3 hours since the last scheduled maintenance which was conducted on 21 April 2024. There were no open defects recorded on the maintenance release and no outstanding or overdue maintenance was noted. 

Aerodrome information

Bacchus Marsh aircraft landing area (ALA) was located about 6.5 km south of Bacchus Marsh, Victoria. It consisted of 2 sealed runways, 01/19 in a north‑south direction and 09/27 in the east‑west direction. The ALA was home to the Bacchus Marsh Aero Club, a pilot training school and several gliding clubs, as well as several privately owned aircraft. 

The ALA was in non‑controlled Class G airspace. Aircraft operating in the area did not require clearance and a common traffic advisory frequency (CTAF) was available for pilot‑to‑pilot communication. 

Bacchus Marsh Aero Club

Bacchus Marsh Aero Club operated several single-engine aircraft that were available to hire for approved club members, including the Cessna 150, 152, 172 and 182 models. Due to its status of being a private flying club and to satisfy insurance purposes, the club had a procedure in place for an independent flight instructor to conduct flight checks on new members prior to them being approved to fly club aircraft. 

Site information 

The accident site was in a barley field, 205 m south of the runway 27 centreline and to the west of runway 19/01 (Figure 1). The fuselage was orientated to the north. Ground impact marks were directly under the wreckage indicating no forward momentum. The damage signatures showed that the aircraft had impacted the field in a steep nose down attitude with the initial ground contact at the leading edge of the left wing. Severe disruption of the cockpit area, wing assembly and rear fuselage had occurred from the impact (Figure 3).

Figure 3: VH-EYU at the accident site

Source: ATSB

Wreckage examination

The ATSB’s examination of the wreckage did not identify any evidence of pre‑existing faults, flight control issues or engine issues and there was no evidence of birdstrike. 

All components were accounted for at the accident site. The right fuel tank had ruptured, while the left tank remained intact. A quantity of fuel was removed from the aircraft fuel tank for onsite testing and was found to be clean and clear of contaminants. Fuel was removed from the carburettor, which was also tested with no water or contaminants found.

The wings and centre fuselage roof section had separated and moved forwards as a result of the impact. Portions of the airframe were removed by first responders prior to ATSB examination, and these were photographed prior to removal. The stall warning horn on the left wing was damaged in the accident sequence and could not be tested for functionality. The flaps were noted to be retracted, which is the position required in the normal take‑off checklist. 

An examination of the seat rails showed that the pilot seat was locked into position and had not moved prior to the accident.

The engine and propeller displayed no pre‑existing damage. The engine was externally examined, and all components were accounted for. The engine was able to be rotated which indicated no significant internal damage had occurred. 

The propeller and flange had fractured from the engine crankshaft and there was evidence of rotation on the fracture surfaces. The propeller displayed minor rotational scoring and rearward bending which was indicative of low rotational energy at the time of impact. 

The throttle control in the cockpit was set at a low power position and had been bent upwards during the impact sequence. 

Survival aspects

The pilot had been wearing a lap/sash seat belt during the accident flight. The extent of the damage to the occupiable space of the aircraft cabin meant that the impact was not considered survivable.

Aircraft stall and spin behaviour 

Aerodynamic stalls

An aerodynamic stall is a rapid decrease in lift and increase in drag caused by the separation of airflow from the wing’s upper surface. A stall occurs when the angle of attack^[6] exceeds the wing’s critical angle of attack,^[7] resulting in the disruption to the smooth airflow over the wing. This can ordinarily occur at angles of around 16° (Figure 4). Due to the sudden reduction in lift from the wing and rearward movement of the centre of lift, an uncommanded nose‑down pitch ensues. 

The US Federal Aviation Administration (FAA) Airplane Flying Handbook (2021) states that:

• Impending Stall—an impending stall occurs when the AOA causes a stall warning but has not yet reached the critical AOA. Indications of an impending stall can include buffeting… or aural warning.

• Full Stall—a full stall occurs when the critical AOA is exceeded. Indications of a full stall are typically that an uncommanded nose down pitch cannot be readily arrested and may be accompanied by an uncommanded rolling motion... 

The FAA Airplane Flying Handbook (2021) also states that for an impending stall the pilot should:

…immediately reduce AOA once the stall warning device goes off, if installed, or recognizes other cues such as buffeting. The pilot should hold the nose down control input as required to eliminate the stall warning. Then level the wings maintain coordinated flight, and then apply whatever additional power is necessary to return to the desired flightpath.

Figure 4: Effect of increasing angle of attack leading to a stall condition

Source: CASA AvSafety, annotated by the ATSB

Aerodynamic spins

A spin can result when an aircraft simultaneously stalls and yaws.[8] The yaw can be initiated by rudder application (through manipulation of the rudder pedals) or by yaw effects from a range of factors that include aileron deflection, torque, wind and engine/propeller effects. A spin is characterised by the aircraft following a downward, corkscrew path and requires significantly more altitude for recovery compared to a wings level stall.

The spin recovery procedure stated in the Cessna 150L handbook was:

For recovery from an inadvertent or intentional spin, the following procedure should be used.

• retard the throttle to idle position

• apply full rudder opposite to the direction of rotation

• after one-fourth turn, move the control wheel forward of neutral in a brisk motion

• as rotation stops, neutralize rudder and make a smooth recovery from the resulting dive. 

Application of aileron in the direction of the spin will greatly increase the rotation rate and delay the recovery. Ailerons should be held in a neutral position throughout the spin and the recovery. Intentional spins with flaps extended are prohibited.

To recover from the spin, the pilot requires sufficient height to conduct the procedure and fly away. During the initial stages of a take‑off, there is insufficient height to perform these actions. 

Control input in a crosswind

In a crosswind, to prevent uncommanded roll, the pilot must turn the control yoke into wind. This will move the ailerons to change the relative angle of attack of each wing (Figure 5). The aileron on the into‑wind wing (right in this case) will move up, create a lower angle of attack and produce less lift. The aileron on the downwind wing (left in this case) will move down, creating a higher angle of attack and more lift. Therefore, resisting the rolling moment created by the crosswind.

Figure 5: Effect of aileron use on angle of attack

Source: Flight Safety Australia

Guidance

The FAA Airplane Flying Handbook (2021) states for take‑off in gusty conditions that:

During take-offs in a strong, gusty wind, it is advisable that an extra margin of speed be obtained before the airplane is allowed to leave the ground. A take-off at the normal take-off speed may result in a lack of positive control, or a stall, when the airplane encounters a sudden lull in strong, gusty wind, or other turbulent air currents. In this case, the pilot should allow the airplane to stay on the ground longer to attain more speed, then make a smooth, positive rotation to leave the ground.

A Civil Aviation Safety Authority publication AC 91‑02 v1.2 – Suitable places to take‑off and land, and the FAA publication Personal minimums for wind both identify that is the responsibility of the pilot in command to consider the winds and determine if the aircraft can be operated safely in the prevailing conditions. The FAA publication advises pilots to conduct their own testing in progressively higher winds to determine both their own capability and that of the airframe.

Meteorological information

Forecast weather

The planned flight from Bacchus Marsh to Lethbridge was within the Victoria graphical area forecast (GAF)[9] region. The Bureau of Meteorology issued a GAF which included the Bacchus Marsh area, at 0900 on 22 October 2024, and was valid from 1000‍–‍1600. The forecast indicated visibility greater than 10 km and no cloud. A Grid Point Wind and Temperature Forecast was issued by the Bureau of Meteorology at 0525 on 22 October 2024. No wind and temperature was available in the Bacchus Marsh area below 5,000 ft. 

The Bureau of Meteorology issued aerodrome forecasts (TAF)[10] and meteorological aerodrome reports (METAR)[11] for Melbourne, Essendon, Avalon and Ballarat airports. A special meteorological report (SPECI)[12] was also issued, which highlighted that a significant wind gust had been recorded. 

There was no record that the pilot had used any personal login to access weather forecasts prior to their flight, from any official sources. It is unknown if the pilot had checked a forecast via other sources which did not require accounts for access.

Nearby airport weather

The actual weather at Bacchus Marsh ALA was not recorded and not available. However, forecasts and observation reports were available for nearby airports. Table 1 shows the recorded winds at Melbourne Airport leading up to the accident. Melbourne Airport is about 38 km on a bearing of 78° True (° T) from Bacchus Marsh. 

Table 1: Wind speed and direction recorded at Melbourne Airport

Source: Bureau of Meteorology 

Table 2 shows the recorded winds at Ballarat Airport leading up to the accident. Ballarat Airport is about 59 km on a bearing of 293° T from Bacchus Marsh.

Table 2: Wind speed and direction recorded at Ballarat Airport

Source: Bureau of Meteorology 

Windsock indication

Figure 6 shows VH-EYU taxiing to the runway threshold in the opposite direction but parallel to the take‑off direction. The visible opening of the orange windsock in the background indicates headwind and crosswind components for take‑off.

Figure 6: VH-EYU taxiing prior to second take‑off

Source: Supplied

Witness observations of the weather

A number of witnesses described the temperature to be ‘very hot’ (27°C) with strong and gusting winds at the time of the accident. The winds were changing in strength (15–30 kt) and direction (between runways 27 and 01) (Figure 7). A flight instructor, who was an eyewitness to the accident stated that they had cancelled a student’s flight which was to occur later in the day due to the gusty conditions. 

FlySto data from a Cessna 172

A Cessna 172 was flying nearby at the time of the accident and landed at Bacchus Marsh ALA 10 minutes after the accident. Data from the aircraft was uploaded to FlySto.[13] This data recorded the average wind from ground level up to 3,600 ft over a 40‑minute period. The wind direction varied between 262° T and 335° T and at speeds from 6–32 kt. At the time of the accident, this aircraft was located 14 km (8 NM) to the south of Bacchus Marsh ALA and had recorded a 27 kt wind from 290° T while on descent. The temperature recorded upon landing was 29°C.

A component of this data will be normal changes in wind speed and direction due to changes in altitude. For this reason, the average winds referenced in FlySto cannot be used to determine exact conditions at ground level at the time of the accident. 

Figure 7: Witness observation (red arc) and recorded data from FlySto (orange arc), showing approximate wind directions and speeds around time of VH‑EYU take‑off

Source: Google Earth, annotated by the ATSB

CCTV and witness video

CCTV recorded the pilot’s arrival at the airport, refuelling, engine run‑up and control checks, and both take‑off runs. All videos showed evidence of strong and gusting winds creating movement in nearby trees and grass. Pitot cover flags on parked aircraft and clothing of people on the apron were observed flapping in the wind. The videos also captured wind noise varying with gusts.

A gliding club located to the east of the ALA had erected a small windsock, which was observed to be moving erratically with the varying wind strength and directions. The witness video provided, showed this windsock to be a smaller commercially available item. Due to its design, it did not meet the standards[14] for wind direction indicators and therefore was not able to provide any information of wind speed. 

Recorded information

CTAF recording

CTAF recordings provided the standard radio transmissions made by the pilot. The recordings also captured the engine sounds each time a transmission was made and showed that the engine sounded normal throughout the duration of the recordings. 

The pilot sounded calm during transmission and voiced no concern with the engine or aircraft after the first rejected take‑off and subsequent return for the second take‑off. 

Aircraft data

The aircraft was not equipped with either a cockpit voice recorder or a flight data recorder, nor was it required to be. Further, there was no active flight tracking equipment or other devices fitted to the aircraft to provide parameters from the accident flight. 

CCTV

The ATSB conducted frame‑by‑frame analysis of the CCTV of the second take‑off. This analysis showed that the groundspeed of the aircraft was 42 kt when the aircraft became airborne.

Related occurrences

AO-2014-023: Cessna 150G, VH-RXM, Loss of control during initial climb, 18 February 2014, Moorabbin Airport

An instructor and student pilot were conducting a trial instructional flight. The aircraft departed with a 3‍–‍4 kt tailwind. The student was operating the aileron and elevator controls, with the instructor operating the rudder. During the initial climb, the student continued to apply back pressure to the control column resulting in a reduction in optimal airspeed, and a higher‑than‑normal aircraft nose attitude. As the instructor attempted to rectify the aircraft’s profile, the right wing dropped, and the aircraft began to descend. 

The instructor’s efforts to recover the aircraft to a normal climb attitude were not successful, and the right side of the aircraft struck the ground. The aircraft bounced, then came to a halt on its left side. The instructor and student egressed through the right door, and both sustained minor injuries. The aircraft was substantially damaged.

NTSB Docket WPR21LA255 Cessna 150L, N1972L, Collision during take‑off, 30 June 2021, Mud Lake Airport (1U2), Terreton, Jefferson County, Idaho, United States

The pilot reported that, upon landing, they saw a crop duster aircraft descending for a short base for landing on the opposite runway. The pilot initiated a go around with the flaps still extended and with a high-density altitude. The aeroplane attained an altitude of about 50 to 100 ft above ground level when the aeroplane stalled, and the left wing dropped. The pilot attempted to recover but did not have enough height before the aeroplane collided with the ground. The aeroplane nosed over and came to rest inverted. The wings and fuselage were substantially damaged. The pilot and passenger sustained serious injuries.

Safety analysis

While there was no evidence that the pilot accessed official weather forecasts on the day of the accident, the pilot may have consulted informal sources, and they were able to experience the weather at Bacchus Marsh prior to departure. Through the movement of the distant windsock, vegetation, pitot covers on parked aircraft and the clothing of people in view of CCTV and video, it was evident that strong gusting winds were present. Noise on the audio track of CCTV also showed gusts were occurring. 

This supported observations of witnesses at the airfield of the conditions throughout the day and at the time of the accident. It is almost certain the wind conditions would have also been evident to the pilot at the time of take‑off. While no weather recording equipment was available at Bacchus Marsh, the evidence available allowed for an estimate of wind varying from west to north at speeds from around 10 kt gusting to 30 kt.  

There was no evidence of problems with the aircraft. The CCTV showed the pilot conducting pre‑take‑off run-up and control checks prior to the first take‑off. Witnesses and analysis of engine sound from CTAF broadcasts from VH‑EYU confirmed that the engine sounded normal. Additionally, post‑accident examination of the aircraft found no evidence of pre‑accident damage which would have affected the flight. 

There was no stated or discernible reason for the first rejected take‑off. The pilot gave no indication of an aircraft serviceability issue in their radio calls. They did not conduct any additional engine run‑up checks or stop the aircraft to perform any exterior airframe inspection. After exiting the runway, the aircraft was taxied without delay to runway 27 for the second take‑off.

On the second take‑off, CCTV analysis showed the groundspeed of the aircraft was 42 kt when the aircraft became airborne. Based on witness observation and the Cessna 150 measurements, the ATSB estimates the aircraft likely had an airspeed of over 50 kt, marginally faster than the 48 kt stall speed of the aircraft. At that time, crosswind was likely to be around 15 kt. 

Witnesses identified and CCTV footage showed that the aircraft’s attitude was unstable after becoming airborne. This indicates that the aircraft was affected by the strong, variable and gusting headwind and crosswind components as the pilot attempted the second take‑off. These uncommanded wind‑driven movements would require constant aircraft attitude adjustments by the pilot.

The flight instructor’s observation of the steep pitch‑up and controlled lowering of the nose which occurred at around 50 ft is consistent with the pilot manipulating the controls to avoid the aircraft descending back onto the runway and to maintain a suitable airspeed and take-off profile. The second uncorrected steep pitch‑up which occurred at around 150 ft, and the subsequent dropping of the left wing and nose resulting in entry into a left incipient spin, was consistent with a fully developed stall and loss of control in flight. This, in turn, was consistent with evidence of the accident site, in which the aircraft wreckage was confined to a small area, with evidence of a high vertical impact and low forward speed. 

In this accident, it is almost certain that, after take‑off and at low level, the aircraft was subjected to a strong and gusting wind. The nature of the prevailing winds increased the likelihood of a drop in airspeed during a phase of flight where the aircraft was flown at a high angle of attack, leading to an impending stall condition. 

It is possible that the impending stall period was very short due to gust strength and the pitch‑up movement created conditions for aerodynamic stall. Further, as the airspeed at take‑off was likely only a few knots higher than the stall speed, there was minimal buffer to account for any sudden drop of wind strength. The evidence indicates that the angle of attack of the wings increased beyond the critical angle, the left wing of the aircraft aerodynamically stalled, and the aircraft entered the incipient phase of a spin. The stalling of the left wing indicates that the angle of attack on the left wing was higher than that on the right. This is likely due to control inputs to counteract a crosswind from the right.

The actions that take place when the aircraft enters a spin require the pilot to retard the throttle. The throttle position in the aircraft was found in a low power setting, which was likely due to the pilot responding to the aircraft entering the incipient phase of a spin. Because the aircraft stalled at a height of about 150 ft, there was insufficient height to recover before the aircraft collided with terrain. 

Findings

From the evidence available, the following finding is made with respect to the loss of control and collision with terrain involving Cessna 150L, VH-EYU, at Bacchus Marsh aircraft landing area, Victoria, on 22 October 2024. 

Contributing factors

• It is probable that the aircraft was too slow on take‑off for the strong and gusty wind conditions and significant crosswind, meaning there was minimal buffer to manage an impending stall.  Shortly after take‑off, the aircraft stalled at a height too low to recover, resulting in a collision with terrain. 

Sources and submissions

Sources of information

The sources of information during the investigation included:

• Bacchus Marsh Aero Club
• Civil Aviation Safety Authority
• Victoria Police
• the maintenance organisation for VH-EYU
• Airservices Australia
• Bureau of Meteorology
• Peninsula Aero Club
• Oxford Aviation Academy
• TVSA Pilot Training
• witnesses
• video footage of the accident flight and other videos taken on the day of the accident
• recorded CTAF communications. 

References

Civil Aviation Safety Authority 2019, Strong and gusty winds, Civil Aviation Safety Authority, Canberra, ACT Strong and gusty winds | Flight Safety Australia

Civil Aviation Safety Authority 2020, Advisory Circular AC 61-16v1.0, Civil Aviation Safety Authority, Canberra, ACT, https://www.casa.gov.au/spin-avoidance-and-stall-recovery-training

Civil Aviation Safety Authority 2020, Part 139 (Aerodromes) Manual of Standards 2019, Civil Aviation Safety Authority, Canberra, ACT, Part139_(Aerodrome)_MOS.pdf pp 196-198.

Civil Aviation Safety Authority 2019, Rudder, ailerons, stalls and spins, Civil Aviation Safety Authority, Canberra, ACT Rudder, ailerons, stalls and spins | Flight Safety Australia

Civil Aviation Safety Authority 2022, Stalls in the circuit, Civil Aviation Safety Authority, Canberra, ACT Stalls in the circuit | Flight Safety Australia 

Civil Aviation Safety Authority 2022, Advisory Circular AC 91-02v1.2, Civil Aviation Safety Authority, Canberra, ACT https://www.casa.gov.au/guidelines-aeroplanes-mtow-not-exceeding-5-700-kg-suitable-places-take-and-land pp21-22.

Civil Aviation Safety Authority 2024, AvSafety: Preventing a stall at low level, Civil Aviation Safety Authority, Canberra, ACT, Preventing a stall at low level

Federal Aviation Administration 2021, Airplane Flying Handbook (FAA-H-8083-3C), Federal Aviation Administration, Washington DC Airplane Flying Handbook 

National Transportation Safety Board 2015, NTSB Safety Alert 19 / Prevent Aerodynamic Stalls at Low Altitude, National Transportation Safety Board, Washington DC NTSB Safety Alert 19 / Prevent Aerodynamic Stalls at Low Altitude

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the Civil Aviation Safety Authority
• the Bacchus Marsh Aero Club
• the National Transportation Safety Board.

Any submissions from those parties were reviewed and, where considered appropriate, the text of the draft report was amended accordingly.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2025 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the Australian Transport Safety Bureau.  Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

Investigation summary

What happened

On the morning of 4 November 2023, a Gulfstream 695A, registered VH‑HPY, was being operated by AGAIR on an instrument flight rules flight from Toowoomba to Mount Isa, Queensland. On board the aircraft were the pilot and 2 camera operators. The purpose of the flight was to conduct line scanning of fire zones located north of Mount Isa. 

About 1 hour and 50 minutes into the flight, while the aircraft was in cruise at flight level 280, air traffic control (ATC) lost radio contact with the pilot. Over the following 30 minutes, ATC made multiple attempts to re‑establish contact, including using alternate frequencies and relaying messages via other aircraft in the vicinity. VH-HPY was observed diverging from track and ATC declared an uncertainty phase for the aircraft.

About 20 minutes later, ATC called the pilot’s mobile telephone, and a brief conversation took place. During the conversation, the pilot’s speech was observed as slow and flat. In response, ATC upgraded the aircraft’s status to an alert phase and initiated their hypoxic pilot emergency procedures. About 10 minutes later, the crew of a nearby aircraft was able to establish contact with the pilot, having been requested to do so by ATC. The alert phase was downgraded to an uncertainty phase and, a short time later, ATC re-established direct contact with the pilot. The uncertainty phase was cancelled 1 minute later.

The pilot confirmed that their oxygen system was operating normally, and they were issued a clearance to undertake line scanning north of Mount Isa. Over the following 4 minutes, the pilot repeated the clearance from ATC 4 times, seeming uncertain about the status of the clearance. The radio recordings during this period indicate that the pilot’s rate and volume of speech had substantially lowered from earlier communications and was worsening. The pilot’s final radio transmission displayed the slowest speaking rate of all their communications during the flight and contained stuttering and operational mistakes. Air traffic control did not attempt to re‑establish contact with the pilot until about 18 minutes later, however no further responses from the pilot were received. 

A short time later, the aircraft departed controlled flight, initially entering a descending anticlockwise turn with an increasing rate of descent. At about 10,500 ft, the aircraft likely transitioned into an aerodynamic spin, with a subsequent average rate of descent of about 13,500 ft/min. The aircraft collided with terrain 55 km south-east of Cloncurry. The 3 occupants were fatally injured, and the aircraft was destroyed by impact forces and a fuel-fed post-impact fire.

What the ATSB found

The ATSB found that the aircraft had a long-term intermittent defect with the pressurisation system that would manifest as a reduced maximum attainable cabin differential pressure. The defect was known about by senior AGAIR management who attempted to have the defect rectified. However, they did not formally record the defect, communicate it to the safety manager, undertake a formal risk assessment of the issue, or provide explicit procedures to pilots for managing it. 

Instead, AGAIR management personnel participated in and encouraged the practice of continuing operations in the aircraft at a cabin altitude that required the use of oxygen, without access to a suitable oxygen supply. This included the pilot of the accident flight, with emails and historical flight data indicating they had a pattern of normalised deviation from safe operating practices by continuing to operate the aircraft when the pressurisation system was defective. In these situations, the pilot was found to have managed the effects of hypoxia by undertaking short descents to lower altitudes and use of the aircraft’s oxygen system, which was designed for emergency use only.

It was identified that during the accident flight the pressurisation system probably did not maintain the required cabin altitude, and the pilot probably continued the flight using the aircraft’s oxygen system, which was unsuitable for this purpose. The pilot’s speech, as captured by air traffic control recordings, demonstrated significant and progressive impairment while the aircraft was operating at about flight level 280. This impairment was consistent with altitude hypoxia, which almost certainly significantly degraded the pilot’s ability to safely operate the aircraft.

While the aircraft was in cruise, both power levers were probably reduced without a descent being initiated, resulting in a progressive reduction of airspeed. The aircraft then entered a descending anticlockwise turn with an increasing rate of descent. At around 10,500 ft control input(s) were almost certainly made, probably an attempt to recover, that transitioned the aircraft from a high‑speed descent to an unrecoverable spin condition that continued until the impact with terrain. 

It was found that the AGAIR head of flying operations (HOFO) did not communicate critical safety information about the known intermittent pressurisation defect when they were phoned by air traffic control about concerns that the pilot was impacted by hypoxia around 37 minutes before the collision. This took place at a time when air traffic control could have taken action to instruct the pilot to descend to a safe altitude. 

Air traffic control personnel involved therefore had no knowledge of the aircraft pressurisation defect from that phone call, and without establishing with the pilot why they had not responded to ATC broadcasts for 1 hour and 13 minutes, they likely reduced their vigilance about hypoxia after being told by the pilot that operations were normal. Consequently, ATC did not re-identify the possibility of hypoxia during the subsequent progressive deterioration of the pilot’s speech. Additionally, the air traffic control ‘hypoxic pilot emergency checklist’ contained no guidance on ceasing the emergency response, which increased the risk of inappropriately downgrading the response during a developing hypoxic scenario. 

It was also identified that AGAIR Gulfstream 690 and 695 aircraft were operated with known defects without being recorded on the aircraft’s maintenance releases, likely as a routine practice. This issue had been reported to CASA in 2019 and a surveillance event was conducted in response. The scope of the surveillance event did not include a crosscheck of maintenance releases against the aircraft logbooks, limiting the ability to determine whether any non-reporting and improper deferral of defects had been taking place at that time.

What has been done as a result

AGAIR amended the organisation’s procedural documentation to provide greater detail on the delegation of management responsibilities, maximum cabin altitude requirements, defect reporting, and the capture of cabin pressure information as part of daily aircraft flight and fuel logs. 

AGAIR also incorporated pressurisation, oxygen and line scanning hazards within the organisation’s hazard register. AGAIR has also contracted a continuing airworthiness management organisation and appointed a new head of aircraft airworthiness maintenance control to monitor defect reporting. 

While the ATSB recognises the changes implemented by AGAIR to date, the actions taken do not address the matters raised relating to effective operational control. The HOFO was responsible for ensuring the operation was compliant with aviation legislation and conformed to company standards. However, the ATSB found multiple instances where these requirements were not met. AGAIR has not addressed how the organisation intends to assure future legislative and procedural compliance by line pilots and management personnel. As such, the ATSB has issued a formal safety recommendation to AGAIR to initiate an independent review of their organisational structure and oversight of operational activities to assure ongoing effective operational control by management.

Airservices Australia advised that it is in the process of conducting a review of the hypoxia in-flight emergency response checklist.

Safety message

This accident highlights the dangers of operational practices that intentionally circumvent critical safety defences. The acceptance of these actions at an individual and organisational level normalises that behaviour and exposes the operation to an unnecessarily increased level of risk. 

This accident also underscores the insidious and deadly potential of altitude hypoxia, and pilots need to be alert to this significant hazard when operating at high altitude. Life support and emergency alerting systems are often the final line of defence against hypoxic incapacitation, and they should only be used in accordance with the manufacturer’s procedures. 

Summary video

The occurrence

Overview

On the morning of 4 November 2023, a Gulfstream 695A, registered VH‑HPY, was being operated by AGAIR on an instrument flight rules[1] flight from Toowoomba to Mount Isa, Queensland, with the callsign ‘birddog 370’. On board the aircraft were the pilot and 2 camera operators. The purpose of the flight was to conduct line scanning[2] of fire zones located north of Mount Isa. The flight had been contracted by Queensland Fire and Emergency Services and was conducted as an aerial work operation.

While the aircraft was in cruise at flight level[3] (FL) 280, air traffic control (ATC) radio contact with the pilot was unable to be maintained. ATC made multiple attempts to re-establish radio communications, but these were initially unsuccessful. ATC also declared an uncertainty phase for the aircraft, later upgrading it to an alert phase. After about 1 hour, the crew of a Royal Australian Air Force (RAAF) aircraft was able to make radio contact with the pilot, and ATC re-established communications a short time later. The alert and uncertainty phases were subsequently cancelled.

A series of radio communications were exchanged between the pilot and ATC, during which the pilot was issued a clearance to undertake line scanning north of Mount Isa. The pilot did not respond to any further calls from ATC. The aircraft departed controlled flight and at 1427 (local time) collided with terrain 55 km south-east of Cloncurry (Figure 1). The 3 occupants were fatally injured, and the aircraft was destroyed.

Figure 1: Flight path overview 

Source: Google Earth, annotated by the ATSB

Departure, climb and cruise

At 1055 on the morning of the accident flight, the aircraft departed Toowoomba Airport with the pilot being provided an ATC clearance for the flight to track to Mount Isa. The pilot was initially cleared by ATC to climb to FL160 and was then issued further instruction to continue the climb to the planned cruise of FL280. The pilot made a brief personal phone call at about 1103 (see Telecommunications), and the aircraft reached FL280 at 1120:30 (Figure 2).

Figure 2: Plot of changes in aircraft altitude and the sequence of radio communication events throughout the accident flight from 1045–1300  

Position information including altitude and time was obtained from ADS-B data that was broadcast from VH-HPY. Source: ATSB

At 1126:55 the flight was transferred to, and the pilot established radio communication with, the controller responsible for the Simpson region on the frequency 126.0 MHz (see Airspace). 

At 1141:12, the pilot contacted the controller and requested clearance to descend to FL150. The requested clearance was provided and, a short time later, the aircraft started to descend. The initial rate of descent reached about 3,900 feet per minute (ft/min), but this slowed as the aircraft continued to descend. At 1151:49, the aircraft levelled off at FL150. At 1157:43, the pilot contacted the controller again and requested clearance to climb back to FL280, which was approved. Shortly after, the aircraft began to climb.

At 1210:19, the Simpson region controller requested the pilot change their radio communication frequency to 122.3 MHz, to maintain radio contact with ground equipment as the aircraft flew further west. The pilot established radio communication on the new frequency and reported to the controller that the aircraft was on climb to FL280. At 1221:49, the aircraft levelled off at FL280. 

At 1245:51, the Simpson region controller requested the pilot change their radio communication frequency to 122.1 MHz as the aircraft continued its journey to the northwest. This change was acknowledged by the pilot, but the controller did not receive radio communications from the flight on the newly-assigned frequency. 

Initial loss of radio communications

Between 1247:51 and 1317:48, the Simpson region controller made 12 separate radio broadcasts attempting to re-establish radio communication with the pilot. The controller also attempted to contact the pilot on high frequency radio, and by relaying messages via the flight crew of a passenger transport aircraft that was operating in the vicinity of VH-HPY. 

During this time the controller identified that VH-HPY was diverging from track, by about 2 km laterally, and the shift manager (SM) was informed (see Air traffic services). At 1318:20, ATC declared an uncertainty phase (INCERFA)[4] (see Emergency phases) and the air traffic management director (ATMD) was made aware of the developing situation (Figure 3). 

Figure 3: Sequence of ATC actions and communication events between 1300–1430

Position information including altitude and time was obtained from ADS-B data that was broadcast from VH-HPY. Source: ATSB

At 1337:46, the ATMD attempted to contact the pilot using the mobile telephone number listed on the flight plan, but the pilot did not answer the call. At 1338:36, the pilot returned the ATMD’s phone call, and they had a brief conversation during which the pilot advised that they had ‘no joy’ on radio frequency 122.4 MHz, rather than the instructed frequency of 122.1 MHz (see Telecommunications). The ATMD determined that the pilot’s speech was ‘slower’ than normal and ‘flat’, and these concerns were shared with the SM at the conclusion of the call. At 1340:00, the INCEFRA was upgraded to an alert phase (ALERFA)[5] (see Emergency phases) and the hypoxic pilot in-flight emergency response (IFER) checklist was initiated (see Hypoxic pilot procedures). 

At 1340:15, the controller commenced radio broadcasts to the pilot as part of the IFER hypoxia checklist. These transmissions included the instructions:

- Oxygen, oxygen, oxygen, descend to one zero thousand feet. 

At the same time, the ATMD called the pilot’s mobile phone, but the pilot did not answer. The ATMD left a voicemail message requesting the pilot check their oxygen and call back ATC. 

At 1341:11, the crew of a RAAF aircraft that was in the vicinity of VH-HPY offered to assist the controller to contact the pilot. The controller agreed and a short time later the RAAF crew reported hearing a broken transmission, possibly from VH-HPY, but they were unable to establish contact with the pilot.

At 1341:31, the pilot of VH-HPY transmitted a radio broadcast on frequency 122.1 MHz, providing callsign, flight level, and radio frequency, but the controller was unable to re-establish 2-way communications. Between 1341:31 and 1350:51, the controller continued to broadcast instruction for the pilot to descend the aircraft to 10,000 ft. The controller also attempted further relays via other aircraft in the vicinity of VH‑HPY on various frequencies, including the international air distress frequency 121.5 MHz. 

At about 1348:00, ATC sent 2 text messages to the pilot’s mobile phone and an email requesting they check their oxygen and pressurisation and contact them on frequency 122.1 MHz. No response was received. 

Re-establishment of radio communications

At 1349:13, the crew of the RAAF aircraft advised the controller that they had heard a ‘weak’ transmission from the pilot of VH-HPY on frequency 118.6 MHz. In response, the controller requested the crew of the RAAF aircraft make another broadcast to include the statement ‘oxygen, oxygen, oxygen descend to one zero thousand feet’. The crew of the RAAF aircraft made 2 such broadcasts and, at about 1350, they established contact with the pilot of VH-HPY. 

During this time, the ATMD and SM telephoned the AGAIR head of flying operations (HOFO), advising that contact had been lost with the pilot of VH-HPY and that they suspected the pilot was potentially affected by hypoxia (see Telecommunications).

At 1350:50 the crew of the RAAF aircraft relayed to the controller that VH‑HPY was ‘ops normal’ and maintaining FL280. ATC subsequently downgraded the ALERFA to an INCERFA. At 1351:08, the controller requested that the RAAF crew instruct the pilot to call ATC on frequency 123.95 MHz. At 1351:59, the controller re-established radio communications with the pilot of VH‑HPY on this frequency and the pilot reported ‘ops normal’. About 1 minute later, ATC cancelled the INCERFA phase.

Between 1352:08 and 1357:34, several communications took place between the controller and the pilot. During this time, and 2 minutes after ATC had cancelled the INCERFA phase, the controller asked the pilot ‘just confirm your oxygen system is ops normal’, to which the pilot responded ‘affirm’. The controller later recalled that they had asked about the oxygen system because they had concerns there was a potential hypoxia event and wanted the pilot to look at the oxygen system in case there was a problem. The ATMD recalled that they requested the controller query the status of the oxygen system as a ‘surety check’. The controller recalled that the pilot’s speech at that time was ‘clear and concise’, and they were satisfied with the pilot’s delivery of speech.

At 1357:34, the pilot was provided with an ATC clearance to undertake operations near Mount Gordon. ATC communication recordings showed that the pilot confirmed the clearance at 1357:43, and then twice requested confirmation that the controller had copied their clearance readback (1359:26 and 1400:15). The controller then responded at 1400:19, advising the pilot that the communications were at low strength and could the pilot adjust their microphone. The pilot replied at 1400:57 and the controller then confirmed they had received the pilot’s confirmation of the clearance. At 1401:23 the pilot then confirmed the clearance again. The controller recalled that, during this time, a lot of activity took place near their console related to the status of the aircraft (see Simpson region controller divided attention). 

The radio recordings indicate that the pilot’s rate and volume of speech had substantially decreased from earlier communications and were worsening. During the radio transmission that commenced at 1401:23 the pilot had difficulty pronouncing the location ‘Cloncurry’ and they incorrectly stated the airwork would take place near ‘Mount Ball’, which was then corrected to ‘Gordon’. 

At 1419:19, the controller requested the pilot change frequency to 122.4 MHz, but no response was received. Between 1419:19 and 1427:15 the controller attempted to contact the pilot 8 times without receiving a response.

Departure from controlled flight

Recorded data indicated that, at 1423:20, the aircraft’s airspeed began to reduce from a cruise airspeed of about 236 KTAS.[6] At 1425:25, the airspeed had decreased to about 138 KTAS and the aircraft departed controlled flight (see Flight performance analysis). The aircraft initially entered a descending anticlockwise[7] turn with an increasing rate of descent. At an altitude of about 10,500 ft, the aircraft transitioned into a tight clockwise helical descent, likely an aerodynamic spin,[8] with a subsequent average rate of descent of about 13,500 ft/min (Figure 4). 

Figure 4: Flight path of VH-HPY during the descent from FL280

Source: Google Earth, annotated by the ATSB

Two witnesses at a nearby mining facility observed the aircraft descending in a nose-down, clockwise, corkscrew motion and described hearing a ‘whirring’ noise. The witnesses recalled that motion momentarily stopped part way down, before re-entering the nose-down corkscrew descent.

At about 1427:15, the aircraft collided with terrain 55 km south-east of Cloncurry. The 3 occupants were fatally injured, and the aircraft was destroyed by impact forces and a fuel-fed post-impact fire.

Context

Personnel information

Pilot

Aeronautical experience 

The pilot held an air transport pilot licence (aeroplane) and a commercial pilot licence (helicopter), issued in February 2005 and August 2009, respectively. At the time of the accident, the pilot had accumulated about 4,900 hours total aeronautical experience, which included about 3,200 hours operating turboprop, jet, and high-performance Royal Australian Air Force (RAAF) military aircraft. This included unpressurised aircraft with supplemental oxygen systems (Pilatus PC-9) and pressurised aircraft (Beechcraft B200 and Learjet L35/36). Training records provided by the RAAF indicated the pilot had completed 2 altitude chamber training exercises,[9] one in 1995 and the second in 2019.

Gulfstream 695A training and experience

In August 2023, the pilot commenced work with AGAIR. They had not previously flown a Gulfstream 695A. 

On 15 August 2023, the pilot undertook Gulfstream 695A training and completed a flight review the following day. This training was arranged by AGAIR, and undertaken in VH-HPY, but the training and review were conducted by an independent training provider. 

During the training, the pilot demonstrated competent use of the aircraft systems including management of the pressurisation system. The pilot also conducted a simulated depressurisation scenario from FL150, which involved the use of oxygen and an emergency descent. The training notes made by the instructor about the pilot’s performance during this activity stated:

Emergency descent - best initiated with roll, using the secondary effect (yaw) to pitch the nose down to the required attitude without causing negative load factor. 

The training and flight review were completed within 2.9 hours of flight time and the pilot was assessed by the instructor as competent to operate the aircraft type as pilot in command (PIC). The pilot commenced flying as PIC for AGAIR on 28 September 2023 and they were initially supervised by the AGAIR chief operating officer (COO) over ‘3 or 4 flights’ (see AGAIR chief operating officer actions). There was no training file kept on the pilot’s performance during the supervised flights. 

In the 3 months after starting with the operator until the accident, they had accumulated a total of about 102 hours flight time, all flying VH-HPY mostly undertaking line scanning flights from Toowoomba.

After review of the draft ATSB investigation report the operator provided a record indicating the pilot of the accident flight completed a ‘line check’ flight in VH-HPY on 9 August 2023 with the AGAIR head of flying operations (HOFO). 

Medical information

The pilot held a class 1 aviation medical certificate that was issued on 27 February 2023 and was valid at the time of the accident. Their certificate had a restriction requiring reading correction to be available while exercising the privileges of their licence. The pilot’s aviation medical records were provided for the period 2022–2023 and their general practitioner records were provided for the period 2021–2023. Overall, these records indicated no significant medical conditions or abnormal physical findings. 

At the time of the accident, the pilot was taking medication for high cholesterol. In 2019 they underwent a coronary angiography, which showed no calcium and no soft plaque formation. The pilot had also visited a cardiologist in December 2021 due to family history, and undertook a stress electrocardiogram in November 2022, which identified no issues. In April 2023, the pilot injured their Achilles tendon and underwent surgical repair. The injury was reported to the Civil Aviation Safety Authority (CASA) on 18 April 2023, and the pilot was cleared to resume flying duties on 22 May 2023. The pilot was reported to have recovered well from their Achilles injury. Overall, the pilot was reported to have been fit, active and healthy, with no known stressors. 

Recent history

The pilot had 8 duty free days prior to the commencement of their most recent period of duty. This period started on 1 November 2023. They conducted a 1.3 hour flight from Essendon, Victoria, to Hay, New South Wales, on 1 November, and a 3.7 hour flight from Hay to Toowoomba on 2 November.

The pilot was reported to have gone to bed at around 2030–2100 the night prior to the accident and was known to wake early and undertake morning exercise. The collision with terrain occurred mid-afternoon after they had been flying about 3.5 hours that day. The ATSB reviewed their recent work-rest history and based on the available evidence, it was considered very unlikely that the pilot was experiencing a level of fatigue known to adversely affect performance.

Camera operator 1

Aeronautical experience

Camera operator 1 joined AGAIR in July 2021. They were not employed as a pilot by the organisation, but they held a commercial pilot licence (aeroplane), issued in February 2020. At the time of the accident, they had about 434 hours total aeronautical experience, including 72 hours on multi-engine piston aircraft.

Medical

Camera operator 1 held a class 1 aviation medical certificate that was issued on 14 November 2022 with no restriction. The medical certificate was valid at the time of the accident. Their aviation medical records were provided for the period 2021–2022. These examinations indicated no significant medical conditions or abnormal physical findings. Camera operator 1 was reported to be in ‘very good health’ with no known medical conditions.

Camera operator 2 

Aeronautical experience

Camera operator 2 was a United States citizen who had experience in the construction and operation of the imaging system fitted to VH-HPY (see Aerial survey camera system). They joined AGAIR in October 2023, and had conducted 5 line scanning flights in VH-HPY prior to the accident flight. They did not hold a flight crew licence, but they had received about 4 hours instructional flight training in the year prior to the accident. 

Medical

Camera operator 2 did not hold an aviation medical certificate, nor were they required to. They were reported to be ‘very healthy’ with no known medical conditions.

Post-mortem and toxicology 

Autopsy results

The post-mortem examinations determined that the occupants of the aircraft had sustained multiple injuries during impact that proved fatal. The results of the examinations did not indicate any significant natural disease that could have contributed to the accident. However, the examinations were limited due to the nature of the impact and resulting fire. There were no indications that the occupants of the aircraft had inhaled products of combustion.

Toxicology results

Toxicology testing was conducted and no drugs were detected, however the validity of the testing was degraded due to changes that occur post-mortem. Alcohol and carbon monoxide testing could not be completed using the samples obtained. 

Aircraft information

General information

The Gulfstream 695A is a high-wing, pressurised, twin-engine aircraft powered by 2 Garrett TPE331-10-511K turboprop engines. The aircraft was designed as a business and personal aircraft with seating capacity of up to 11 people.

The accident aircraft, serial number 96051, was manufactured in 1982 and in January 1983 commenced operations in South Africa. During this time the aircraft’s air conditioning system was replaced with an approved alternative system.[10] In 2014, prior to the aircraft being exported to Australia, the aircraft underwent refurbishment, which included a new avionics suite and interior, and the aircraft was repainted. Additionally, the original Dowty Rotol propellers were replaced with Hartzell propellers under a supplemental type certificate.[11]

The aircraft was first registered in Australia as VH-HPY on 11 November 2014. Its registration was held by AGAIR since 14 September 2016 and was initially used for birddog flights[12] (Figure 5). 

The aircraft was configured with 2 crew seats, 4 passenger seats, and a bench seat in the rear. The last periodic inspection was completed on 1 November 2023. At this time, the aircraft had accumulated 7,566.1 hours total time in service.

Figure 5: VH-HPY August 2023

Source: Cameron Marchant

Aircraft systems

Aerial survey camera system

To expand its operational capabilities, AGAIR elected to modify VH-HPY to undertake aerial surveys of natural disasters such as bushfire and flood by fitting an Overwatch Imaging TK‑7 camera system. 

To modify the aircraft, AGAIR engaged an approved aircraft design organisation to prepare the engineering order,[13] and the installation was carried out by General Aviation Maintenance (GAM). Work on the modification began in June 2021 and had been partially completed when the aircraft recommenced operations in August 2021. In November 2021, VH‑HPY returned to GAM and the modification was completed and certified on the maintenance release.[14] The engineering order, associated drawings, and a flight manual supplement specific to VH-HPY, were approved by the aircraft design organisation in February 2022.

Pressurisation system

Generally, aircraft that are intended to be operated at altitudes over 10,000 ft are equipped with a pressurisation system. As the aircraft climbs, the air pressure outside the cabin decreases, and at the same time the aircraft’s pressurisation system maintains the pressure inside the cabin to a level that allows normal breathing (without the use of supplemental oxygen). The environment maintained by the pressurisation system is known as the cabin altitude. The difference between the pressure inside the cabin and the pressure outside the cabin is known as cabin differential pressure. Pressurised aircraft have a stipulated maximum differential pressure because of the loads that pressurisation places on an aircraft’s fuselage.

The Gulfstream 695A is pressurised by ducting air from both engines (known as bleed air) into the cabin and controlling its flow overboard via outflow safety valves to maintain the desired cabin pressure. The source of bleed air can be selected within the cockpit. A cabin pressure controller, also located within the cockpit, is used to manage the cabin pressure from take-off, through climb, cruise, and descent. The controller also prevents exceedance of the maximum differential pressure of 6.8 psi (see Appendix A – Gulfstream 695A systems information). The Gulfstream 695A is certified to operate up to 35,000 ft above mean sea level. At this altitude, and at the maximum differential pressure, the cabin altitude would be 9,600 ft. The pilot’s operating handbook (POH) requires the pilot to ‘limit flight altitude to maintain 10,000 ft cabin altitude’ should the cabin altitude exceed the selected value.

Figure 6: VH-HPY cockpit layout 

Note: Image captured prior to the accident. Source: Cameron Marchant, annotated by the ATSB

The Gulfstream 695A is fitted[15] with a cabin altitude visual and aural warning system that activates when the cabin altitude is at or above 11,000 ft (±500 ft) (Figure 6). When activated, ‘CABIN ALT’ illuminates in red on the glareshield annunciator panel and flashes for 10–20 seconds before remaining steady. This is accompanied by an aural tone that pulses 6 times per second. The aural warning can be silenced by pressing a button on the left engine power lever (see Appendix A – Gulfstream 695A systems information).

In the event of illumination of the ‘CABIN ALT’ annunciator, accompanied by the aural warning tone, the POH requires the pilot to don their oxygen mask, verify passengers were receiving oxygen, and initiate a descent to 12,000 ft or below (Figure 7).

Figure 7: Cabin altitude annunciator emergency procedure

Source: Ontic

Oxygen system

The Gulfstream 695A is equipped with an oxygen system that provides life support in the event of an emergency. The POH states that:

The airplane is equipped with a high pressure, gaseous oxygen system which provides supplemental breathing oxygen to the crew and passengers in the event of cabin depressurization during high altitude operation, or in the event cabin air becomes contaminated. The system will provide oxygen for sufficient time to permit a planned descent to an altitude where supplemental oxygen is no longer required.

Oxygen is stored in a cylinder located in the rear fuselage and, when full, can supply oxygen to 3 people for about 29 minutes. The cylinder is full when filled to 1,800 psi. The passenger oxygen system switch is recessed into the sidewall on the right side of the cockpit, alongside a cylinder pressure gauge for the aircraft oxygen system (see Appendix A – Gulfstream 695A systems information).

The pilot and copilot oxygen masks are designed for rapid donning and are positioned on hooks immediately behind the pilot and copilot seats for ease of access. The masks incorporate a microphone for radio communications. Passenger oxygen masks are stowed in containers at various locations in the cabin lining above the passenger seats (see Appendix A – Gulfstream 695A systems information). 

Autopilot

The autopilot fitted to VH-HPY was a Collins AP-106 and it was integrated with the aircraft’s instruments. The Collins AP-106 is a 3-axis system that stabilises the aircraft about its roll, pitch, and yaw axes. The system can operate in various modes including pitch hold, heading, navigation, approach, back-course, altitude, and indicated airspeed. Both pilot and copilot control wheels have an autopilot release switch (see Appendix A – Gulfstream 695A systems information). 

A subcomponent of the autopilot system, the trim servo monitor, has fault detection and diagnostic capabilities that automatically disengage the autopilot if a discrepancy or malfunction is detected. One such potential fault condition is the exceedance of threshold voltages within a servo as it works against an aerodynamic or mechanical force. 

The ATSB interviewed 3 pilots who had previously flown VH-HPY for AGAIR. Two pilots described the autopilot as being unreliable at times. One recalled that the autopilot would not hold altitude well and would ‘chase’ the target by +/- 100 ft. Another recalled that the system would be fine in smooth air, but if the aircraft experienced turbulence that required multiple control inputs, the autopilot would disconnect without any prior indication after about 10 minutes. Another pilot regarded the autopilot favourably. Maintenance records for VH‑HPY show multiple instances of autopilot defects and subsequent rectifications.

Engine controls

The Gulfstream 695A engines are controlled from the cockpit using a power lever and a condition lever for each engine. The autopilot does not interface with the engine controls.

Radios

The aircraft was fitted with very high frequency (VHF) and high frequency (HF) radios, along with an additional communication unit for birddog flights and a satellite phone. Pilots wore headsets with boom microphones and were able to transmit by pressing a thumb-operated button on the outboard grip of each control wheel. Handheld microphones were also stowed on each control column.

On the day of the accident, routine communications between air traffic control and VH-HPY were via VHF. VHF radio is limited to ‘line of sight transmissions’, with communication range increasing with aircraft altitude.

Maintenance history

Recent maintenance

The ATSB reviewed the maintenance records for VH-HPY. This included records from when the aircraft was operating in South Africa (from 1983 to 2014) and the Australian records (from 2014 to 2023).

The last maintenance activity prior to the accident was carried out by General Aviation Maintenance (GAM) at Essendon Airport, Victoria, in late October 2023. The work carried out was predominately scheduled maintenance along with some minor defect rectifications. The maintenance provider also carried out checks on the left and right engine bleed air valves after being informed by the AGAIR chief operating officer (COO) that the pressurisation system was malfunctioning (see Aircraft pressurisation defects). The aircraft was released for service on Wednesday 1 November 2023, 3 days prior to the accident flight. The maintenance provider advised that after the first flight, the pilot who accepted the aircraft called and reported to them that the aircraft systems including pressurisation were working normally.

Aircraft pressurisation defects

In 2011, while the aircraft was operating in South Africa, the cabin door seal was replaced to address a pressurisation issue. In 2013 a defect was recorded where the maximum cabin differential pressure of 6.8 psi could not be reached. It was determined that cabin air was leaking from the cabin doorstep area, and this was rectified. Correspondence showed that, when preparing the aircraft to be exported to Australia, the aircraft was not capable of attaining the maximum cabin differential pressure. Significant work was carried out to rectify the issue, including major component replacements, and the cabin interior was removed for access to seal the fuselage.

When VH-HPY was purchased by AGAIR in 2016, maintenance was then provided by GAM at Essendon Airport. The aircraft was reportedly difficult to pressurise when it arrived, which was identified to be because of a leak from a sub-component of the pressurisation system known as a volume tank. Additionally, to address the pressurisation issue a few minor cabin leaks were repaired. A pilot who had flown VH-HPY when it initially entered service with AGAIR recalled that its pressurisation system did function, however if the aircraft rate of climb was high, the pressurisation system would malfunction.

Two of the pilots who had previously flown VH-HPY for AGAIR recalled intermittent pressurisation issues, where the aircraft would not pressurise higher than 2 psi differential pressure. The third pilot reported the pressurisation was okay but had noticed the high rate of climb issue. The unreliability of the pressurisation system reportedly could be managed by selecting the maximum flow of bleed air to the cabin (which can be used at any time except take-off and landing), and by turning the cabin heating up. Additionally, it was also reported that pressurisation seals in the cockpit for the rudder controls were known to leak, and during a flight in late August 2020, the seal dislodged and depressurised the aircraft. On 4 August 2023, the AGAIR HOFO said to GAM that the pressurisation system was working ‘perfectly’.

On 16 October 2023, the pilot of the accident flight emailed the AGAIR COO stating that the pressurisation of VH-HPY was ‘stuck on 2.0 differential for [a] prolonged period’ and because they needed to operate at FL280, they had ‘used a bit of oxygen’ (see Pilot of the accident flight actions). According to the Gulfstream 695A POH, operating at FL280 with a differential pressure of 2.0 psi will result in a cabin altitude of 19,800 ft. The email also requested the aircraft oxygen cylinder be refilled by a maintenance provider at Toowoomba, Queensland where the aircraft was based at the time. Records from the maintenance provider showed that the oxygen cylinder was serviced (refilled) from 1,000 psi to 1,700 psi on 18 October 2023 (see Appendix A – Gulfstream 695A systems information).

On 22 October 2023, the pilot of the accident flight emailed the AGAIR COO and chief executive officer (CEO), who also held the positions of HOFO and head of aircraft airworthiness maintenance control (HAAMC), advising them of issues relating to the pressurisation system of VH-HPY. The email stated there was ‘no change…same cycles and fixes’. The defect was described in the email as the cabin differential being stuck at 2.2 psi (see Pilot of the accident flight actions). 

On 27 October 2023, the AGAIR COO operated the aircraft as PIC and captured a video that showed the aircraft at FL280 with a cabin altitude of 19,000 ft (see AGAIR chief operating officer actions). The COO attempted to ascertain why the pressurisation system was malfunctioning by using the bleed air selector (see Appendix A – Gulfstream 695A systems information) to shut off engine bleed air from each engine in turn. When the pilot selected ‘RIGHT CLOSE’, there was no change in cabin altitude, or when ‘BOTH OPEN’ was re-selected. When ‘LEFT CLOSE’ was selected, the cabin vertical speed indicator showed the cabin altitude climbing at 2,000 ft/min. 

The video was sent to the maintenance provider and the aircraft was flown to their facility on 29 October 2023 for scheduled maintenance. The left and right engine bleed air valves were removed and functionally checked in-house before being refitted to the aircraft. The maintenance provider reported that no faults were found during the valve functional checks or when the pressurisation system was later checked on the ground. The maintenance provider stated that, prior to the completion of maintenance, the aircraft oxygen system was refilled. A maintenance release was issued on 1 November 2023 and the aircraft re-entered service.

Service letters to address cabin leaks

In September 2008, the then type certificate holder for the Gulfstream 695A, and other aircraft in the series, issued 2 service letters with guidance for addressing cabin pressurisation leaks. Service letter 382 was for aircraft in the series that were pressurised ‘to the floor’, while service letter 383 was for aircraft that were pressurised ‘to the skin’. Service letter 383 was applicable to the Gulfstream 695A and it stated:

A recurring problem in pressurized Twin Commanders is maintaining cabin pressure when flying at high altitude. This publication is presented in an effort to standardize the procedure for sealing the known and most significant leakage areas.

The service letter advised that to establish a leakage rate, the aircraft was to be pressurised on the ground using either the engines or with a pressurisation unit. Aircraft that exceeded the maximum allowable leakage rate required rectification. The service letter identified the locations where the most significant leaks occur and provided detailed instructions to address them.

Operations with unserviceable pressurisation system components

The Gulfstream 695A POH contains a minimum required equipment list (MREL) detailing components and systems that must be operable for the aircraft to be considered airworthy. It also lists components and systems that can be inoperable provided that certain operating limits were followed. For inoperative pressurisation system components, the MREL operating limitation requires the aircraft to be only operated unpressurised (see Supplemental oxygen legislative requirements).

Recording of aircraft defects

Requirements

The maintenance release document used for VH-HPY was a standard Civil Aviation Safety Authority (CASA) form 918. The document was used to identify the maintenance release period of validity, list scheduled maintenance due in that period, and to record the hours flown along with landings and pressurisation cycles.[16]

Another principal function of the maintenance release was to record defects and major damage that occurred during the maintenance release period of validity and show the actions taken to rectify them. Part 4B of the Civil Aviation Regulations 1988 did not make a distinction between minor and major defects. However, major defects were defined as:

… those that have caused, or that could cause either: a primary structural failure, a control system failure, an engine structural failure, or a fire. 

Parties required to make entries (known as endorsements) on the maintenance release for defects or damage included the holder of the certificate of registration, the operator, and the flight crew. When a defect was endorsed on the maintenance release, the aircraft was not able to be flown until a formal assessment and deferral of the defect was carried out, or an entry was made to ‘clear’ the original endorsement (known as a clearing endorsement). Clearing endorsements were generally made by approved maintenance personnel, and in accordance with approved data such as the aircraft maintenance manual.

The AGAIR operations manual (OM) required the PIC to record defects and their symptoms on the aircraft’s maintenance release. The PIC was then required to liaise with the HAAMC, who would in turn liaise with the maintenance provider to determine what action was required.

Provision was given in the OM to defer defects that ‘do not impinge on the airworthiness of the aircraft’. Examples of this were given in the manual:

...the Pilot-in-command must consider whether or not the defect will render the aircraft unserviceable for a particular category or type of operation. For instance an unserviceable landing light would not render the aircraft unserviceable for day VFR operations but would render it unserviceable for night operations.

…

…some minor defects such as paint scratches or dents in the structure would not normally impinge on airworthiness whereas cracks in a wing spar certainly would.

The OM contained provision for the use of minimum equipment lists (MEL) supplied by the aircraft manufacturer. Prior to their use by AGAIR, an MEL was required to be approved by CASA, specific to a particular aircraft and operator. The MEL[17] provisions stated in the Gulfstream 695A POH were not approved for use with VH‑HPY at the time of the accident.[18]

Unapproved recording of defects

Some defects that were identified on VH‑HPY and another AGAIR aircraft, VH‑LVG, were recorded using unofficial means to the operator or maintenance provider. On 21 April 2021, the AGAIR HOFO emailed GAM requesting various tasks to be carried out on VH‑HPY, VH‑LVG, and VH‑LMC when the aircraft arrived for maintenance. The email also listed defects on each of the aircraft. None of the 4 defects listed for VH‑HPY in the email had been entered on the relevant maintenance release. Other examples included emails from the pilot of the accident flight to AGAIR managers describing a pressurisation defect with VH‑HPY (see Recording of pressurisation defects), and an internal GAM email listing defects on VH‑LVG.

The ATSB interviewed pilots who had flown VH‑HPY for AGAIR. One pilot recalled that defects would be communicated by phone to GAM. Other pilots recalled that defect lists were compiled to be rectified during the aircraft’s next scheduled maintenance. 

The ATSB reviewed a total of 15 expired maintenance releases¹⁴ that had been retained with the maintenance logbooks from VH-HPY. These maintenance releases dated from November 2014 when VH‑HPY was first registered in Australia. Of these maintenance releases, 13 were from when the aircraft commenced operations with AGAIR in September 2016, and defect entries had been made on 6 of these. The defect entries had been predominately made by the maintenance provider, and the remaining 7 maintenance releases were either blank or had entries for scheduled maintenance activities.

Recording of pressurisation defects

After VH-HPY sustained an in-flight depressurisation in August 2020, an entry for the defect and a clearing endorsement was made by a licensed aircraft maintenance engineer (LAME) on the maintenance release. 

Of the remaining known instances of pressurisation defects, there were no relevant entries on the aircraft’s maintenance releases (Table 1).

Table 1: Recording of known pressurisation defects affecting VH‑HPY since 2016

Meteorological information

Meteorological records[19] from the Bureau of Meteorology (BoM) at the time of the accident were reviewed by the ATSB. This predicted westerly winds at 40 kt, temperature −30°C, with no significant nearby weather events at FL280.

Meteorological conditions were also recorded by the BoM automatic weather station at Cloncurry Airport (55 km north-west of the collision location). At 1430 the surface wind was 6 kt from 190° true, visibility greater than 10 km, no detected cloud, temperature 40°C, dew point 2°C, and no rainfall since 0900.

Recorded data 

The aircraft was not fitted with a flight data recorder or a cockpit voice recorder, nor was it required to be. During the accident flight, data was being transmitted by the automatic dependent surveillance broadcast (ADS-B) and Mode S transponder[20] equipment fitted to the aircraft. Flight data was also being broadcast from a TracPlus[21] unit fitted to the aircraft, which could be used by the fire services and AGAIR to track the location of the aircraft during flight. A navigational application (OzRunways) was installed on a tablet computer on board the aircraft and that device also broadcast flight data. The OzRunways data was recorded at 5 second intervals. The parameters captured from all systems were: time, aircraft position, GPS and pressure (barometric) altitude, altitude rate of change, groundspeed, and heading.

Navigation system

A Garmin GTN-750 navigation system was recovered from the accident site and transported to the ATSB Canberra technical facility. Examination of the unit identified that it was not recording flight data. 

ADS-B data

The ADS-B data provided the highest reporting frequency (~0.5 seconds), and altitude was reported to the nearest 25 ft. This data was captured from shortly after departure until the aircraft descended to about FL240 during its final descent (Figure 8). 

Figure 8: Altitude profile of the accident flight throughout its duration with key moments (phases) displayed

The blue trace represents pressure altitude and the green trace represents GPS altitude. Source: ATSB

Pressure and global positioning system altitude discrepancy

The ADS-B data that was broadcast from the aircraft during the accident flight contained a discrepancy between the pressure altitude and the GPS altitude (Figure 8).[22] At the start of the second cruise phase, the broadcast pressure altitude was 28,000 ft while the GPS altitude was 29,400 ft. At the end of the second cruise phase (approximately 2 hours later), the broadcast pressure altitude was 28,050 ft while the GPS altitude was 29,750 ft. The difference in pressure and GPS altitudes over the entire flight varied with altitude and flight time and is shown on a scatter plot below (Figure 9).

Figure 9: Scatter plot of pressure and GPS altitude discrepancy with altitude (left) and over time (right)

Source: ATSB

When the above data was corrected for local barometric pressure and GPS ellipsoid modelling, the difference in altitudes at the end of the second cruise phase of flight was about 1,400 ft. The GPS altitudes from ADS-B, OzRunways and TrackPlus, which had independent GPS sources and data processing, were broadly aligned over the entire flight, and it is therefore likely that the pressure altitude was reading low and the aircraft was likely flying at FL294 (i.e. the actual position of the aircraft was likely higher than indicated). The reason for the discrepancy could not be determined, although a static source leak inside the cabin could not be discounted. 

Initial descent to FL150

At 1141:12, while at FL280, the aircraft commenced a descent to FL150. The aircraft’s flight profile during this period was erratic with a fluctuating rate of descent that peaked to about 4,200 ft/min. The aircraft’s heading remained steady during the descent. The aircraft then maintained FL150 for a period of about 6 minutes before climbing back to FL280. No reason for the descent was provided to air traffic control and it was not part of the submitted flight plan. The AGAIR COO stated there was no operational reason for the descent to occur.

Flight performance analysis

General

The ADS-B, OzRunways and TrackPlus position and groundspeed data, combined with aircraft performance data, forecast conditions, and actual environmental conditions, were used to formulate likely aircraft performance during the flight. The engine power (maximum continuous power (MCP)), knots true airspeed (KTAS), knots calibrated airspeed (KCAS),[23] and vertical speed was calculated at points in time during the initial cruise, initial descent and the secondary cruise (Table 2). 

Table 2: VH-HPY performance assessment