Safety Summary

What happened

On 11 September 2016, the pilot of a Cessna 172RG, registered VH-MKG (MKG), was observed moving the aircraft out of a hangar at Parafield Airport. The aircraft was positioned on the apron in front of this hangar. The pilot then hand swung the propeller to start the engine, with no one at the aircraft controls. Following the hand start, the uncontrolled aircraft taxied a short distance before colliding with a parked Piper PA-32 Saratoga. Although not struck directly by the propeller, the pilot was fatally injured either by being struck by the aircraft or in the subsequent fall as the aircraft taxied away. The pilot's dog was unsecured in the aircraft.

What the ATSB found

The ATSB found that the battery installed in MKG had insufficient charge to start the engine, and that the pilot started the engine by hand swinging the propeller. The aircraft was not adequately secured during the hand start, resulting in fatal injuries to the pilot and damage to another aircraft when it taxied without pilot control.

Safety message

Hand swinging an aircraft propeller is recognised across the aviation industry as a hazardous procedure. Although hand swinging is permitted under the civil aviation regulations, it should only be undertaken when no other alternatives exist to start the aircraft engine and all necessary precautions have been taken to mitigate the hazards.

Additionally, unrestrained animals in the aircraft cabin have the potential to adversely affect safety during aircraft operations.

Final position of VH-MKG against the Saratoga

Source: ATSB

The occurrence

At approximately 1300 Central Standard Time^[1] on Sunday 11 September 2016, the owner/pilot (pilot) of a Cessna 172RG aircraft, registered VH-MKG (MKG), arrived at Parafield Airport. MKG was located in a hangar on the aerodrome, where the pilot was employed on a contract basis as a check and ferry pilot and aircraft maintenance engineer.

The ATSB was advised that the pilot had been conducting part of a 100 hour inspection, and other scheduled maintenance, on MKG throughout the weekend. The battery installed in MKG had reportedly been on charge during this maintenance.

At around 1600, witnesses reported seeing the pilot manually reposition MKG outside of the hangar. The aircraft was parked, facing approximately south-west, into the wind. The witnesses observed an initial pull through of the propeller by the pilot, before the pilot returned to the cockpit area for a short time.

The pilot then returned to the front of the aircraft and hand swung the propeller for a second time, resulting in the aircraft engine starting. MKG then taxied without pilot control, turning approximately 45 degrees on a left arc, before colliding with a Piper PA-32 Saratoga, registered VH-HYM, that was parked on the apron, approximately 35m from MKG.

Throughout the engine start and uncontrolled taxi, the pilot avoided being struck directly by the propeller. However, possibly in an attempt to re-enter the cockpit to regain control of the aircraft, the pilot's fatal injuries likely resulted either from being struck by MKG as it taxied or in the subsequent fall.^[2]

The impact of the collision pushed the Saratoga about 10m from its parked location. Both aircraft came to rest approximately parallel to each other, facing in opposite directions, with MKG's propeller embedded in the underside of the Saratoga's left wing. The nose cowl of MKG was also wedged under the Saratoga's wing, lifting its left main wheel clear of the ground.

The pilot's dog was found unrestrained in the aircraft cabin and was removed by emergency responders approximately 90 minutes after the accident.

Figure 1: The approximate initial and final positions of VH-MKG and VH-HYM, and the approximate track of MKG. Inset shows the final position viewed from behind MKG

Source: Google Earth, annotated by ATSB.

Starting procedures

The starting procedures for normal operations were contained in the pilot operating handbook (POH) for the Cessna 172RG. It included a checklist of actions to be taken before starting the engine and a starting engine checklist.

In normal operations, the aircraft electrical system was used to start the engine. This required the battery to have sufficient charge to engage the starter motor. Although the battery had been on charge the preceding day while maintenance was undertaken, it was not capable of maintaining sufficient charge to start the engine.

The aircraft was equipped with a ground service port where a ground power unit (GPU) could be connected. The service manual indicated a GPU was intended as a power source for prolonged ground maintenance requiring the use of electrical power. It also indicated, without restricting it to these conditions, that it could be used for cold weather starting. A GPU was available in the hangar where the aircraft was located.

Hand starting procedures

There were no specific procedures to hand start MKG. Civil Aviation Regulation 231 - Manipulation of propeller (CAR 231) permitted the pilot in command to hand swing a propeller to start the engine, provided no assistance was readily available, no passengers were on board the aircraft and adequate provision was made to prevent the aircraft moving forward.

Generic guidance on hand swinging a propeller, published by the Civil Aviation Safety Authority (CASA), the US Federal Aviation Administration (FAA) and various pilot forums, covered topics including:

• deciding to hand start
• positioning the aircraft
• securing the aircraft
• setting the engine controls
• having assistance.

While CAR 231 permitted hand swinging, the guidance available highlighted the increased risk associated with this starting method, and that it should be considered an emergency procedure, used only when absolutely necessary.^[3]

The aircraft was positioned appropriately according to the guidance, outside of the hangar, on firm, flat, level ground, with no obstacles directly ahead.

The guidance advised that:

• chocks of an appropriate size and material should be applied to both main wheels
• the aircraft should be tied down adequately, using an appropriate restraint
• the brakes should be set
• the fuel system and engine controls set for a normal start.

CAR 231 requires the person manipulating the propeller to know the correct starting procedure for the aircraft. Additionally, it allows for assistance to be provided by having a qualified person at the controls of the aircraft, if a suitably qualified person is available. The FAA handbook noted that 'the procedure should never be attempted alone.'^[4]

Securing the aircraft

Wheel Chocks

A single set of small wooden chocks were located about 15m from the hangar doors, in the approximate area MKG was positioned prior to start-up. The distance between the chocks was consistent with both the nose and main wheels of MKG, with a small gap. It was probable that this gap resulted from forward chock sliding along the ground a short distance as the aircraft rolled over it. A set of aircraft chocks consisting of two aluminium angles connected by a chain were located in the aircraft.

Brake system

The aircraft had a single disc, hydraulically actuated brake on each main landing gear wheel. The brakes were operated by applying pressure to the top of the rudder pedals. When the aircraft was parked, both main wheel brakes were able to be set by using the parking brake. The POH instructed that 'to apply the parking brake, set the brakes with the rudder pedals, pull the handle aft, and rotate it 90˚ down.' A ratchet spring then holds the park brake in position.

On-site examination of the aircraft brake system established that the park brake was inoperative. The ratchet spring from the park brake handle had fractured, which rendered the park brake system unable to independently remain locked and set. A thorough search of the aircraft cabin did not locate the remainder of the ratchet spring. Examination of the park brake assembly at the ATSB's technical facilities in Canberra was unable to indicate whether the park brake mechanism was operative prior to the accident.

Tie down

A tie down kit was located in the aircraft, but there was no provision for a tie down in the location the aircraft was parked.

Throttle control

The throttle control was of the push-pull type, incorporating a friction lock, which is rotated for the desired friction level. The throttle is open in the fully forward position and closed in the fully aft.

Post-accident inspection of the aircraft controls found the throttle to be at about one third of its possible travel. The friction knob was consistent with no friction on the throttle control.

The measured throttle position was equivalent to a higher setting than the POH engine start checklist position. However, as the friction lock was not set, it could not be determined if this was the same position as when the aircraft propeller was hand swung.

Related occurrences

A review of the ATSB occurrence database identified 39 other reported incidents involving hand starting an aircraft resulting in injuries and substantial damage to property. The database contained all reported occurrences from 1969. The majority of incidents identified inadequate aircraft restraint and excessive throttle settings as factors in the aircraft moving after a hand start. Of these, a number were identified where the aircraft park brake and wheel chocks were used but were not adequate to restrain the aircraft. This included the investigation detailed below.

ATSB investigation 199401851

The pilot attempted to start the engine for the return flight to Darwin, but the starter motor failed to operate. He then applied the handbrake, chocked the nose-wheel and hand-swung the propeller. After several attempts the engine fired then ran at a high RPM speed causing the aircraft to jump over the chock and head towards the airport fence. After unsuccessfully attempting to enter the cabin the pilot tried to grab a main wheel, but missed. He next grabbed at the tailplane but was knocked to the ground. The empty aircraft then ran through the airport fence, across a road and into a ditch, where it came to rest suffering substantial damage.

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1. Central Standard Time (CST): Coordinated Universal Time (UTC) + 9.5 hours
2. At the time of publication, the Coroner's report had not been finalised. This report will be updated if there are any significant changes to the preliminary findings
3. CASA Safety Video - Prop Swinging available at https://www.youtube.com/CASABriefing
4. FAA Airplane Flying Handbook, FAA-H-8083-3A, 2004

Safety analysis

Starting procedures

Normal operating procedures for the aircraft relied on the battery having sufficient power to start the engine. Evidence gathered during the investigation indicated that the battery was known by the pilot to be unserviceable prior to the accident. It could not be determined why the battery had not been replaced prior to conducting the ground run. Similarly, it was unable to be determined why the available GPU was not used.

The pilot was known to have hand swung aircraft previously, including MKG. The use of either the park brake or wheels chocks, or a combination of both, may have been sufficient to hold the aircraft on previous occasions. However, the aircraft manufacturer indicated that neither the use of chocks nor the park brake were designed to hold the aircraft during an engine start, and were only intended to hold a parked aircraft.

The pilot was hand starting the aircraft unassisted, using only small chocks and without tying down the aircraft, and would therefore have been relying on the park brake being set. If the spring was broken prior to the park brake being set, or broke at the time the brake was set, the pilot would have been alerted to this as the park brake handle would have returned to its initial position. It remains possible that the spring failed between the time the brake was set and the time the engine was started, leaving the pilot unaware that the park brake was not set. This reinforces the recommendations to have a qualified second person at the controls when attempting to hand start.

Other factors that increased risk

Unrestrained animal

Civil Aviation Regulation 256A - Carriage of animals, allows animals to be transported on aircraft. The regulation requires any animal to be in a container or adequately restrained in order to prevent adversely affecting the safe operation of the aircraft.

While it could not be determined in this instance if the presence of the dog had any impact on the accident, an unrestrained animal in the cockpit or cabin area of an aircraft increased the risk of inadvertent interference with aircraft control settings.

Findings

From the evidence available, the following findings are made with respect to the ground handling accident involving Cessna 172RG, registered VH-MKG, Parafield Airport, South Australia on 11 September 2016.

These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• The aircraft battery had insufficient charge to start the engine, resulting in the pilot starting the engine by hand swinging the propeller.
• The aircraft was not adequately secured during the hand start and had no one at the controls, resulting in fatal injuries to the pilot and damage to another aircraft when it taxied away.

Other factors that increased risk

• Unrestrained animals in the aircraft cabin can adversely affect safety during aircraft operations.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• Witnesses
• Maintenance staff
• the Civil Aviation Safety Authority
• Adelaide Airport Limited
• Cessna (Textron Aviation)
• South Australia Police

References

FAA-H-8083-3A, Airplane flying handbook. (2004). U.S. Dept. of Transportation, Federal Aviation Administration, Flight Standards Service.

Information Manual, Cessna Model 172RG. (1983). Cessna Aircraft Company, Wichita, Kansas USA

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act 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 Cessna (Textron Aviation), the Civil Aviation Safety Authority and the United States National Transportation Safety Board.

Submissions were received from the Civil Aviation Safety Authority and the United States National Transportation Safety Board. 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 2017 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

What happened

On 7 September 2016 at 1720 UTC,^[1] Scoot Airline flight TZ026, a Boeing 787 aircraft, registered 9V‑OFG, departed Singapore on a scheduled passenger transport flight to Melbourne, Victoria.

Flight TZ026 made an approach to Melbourne Airport runway 34 and landed without incident at 0021 UTC on 8 September 2016. During the landing roll, the flight crew used maximum reverse thrust in order to vacate runway 34 at Taxiway F (Figure 1). After the aircraft exited the runway onto Taxiway F, air traffic control (ATC) instructed the flight crew to change radio frequency to the ATC Ground frequency. The surface movement controller (SMC) then provided the flight crew with their taxi instructions.

The flight crew proceeded to taxi the aircraft from Taxiway F, right onto Taxiway T, then another right onto Taxiway A. As they started to taxi down Taxiway A, they heard a comment on the Ground frequency about smoke. The flight crew were unsure if the comment was in reference to their aircraft, so they queried the SMC. The SMC responded that flight TZ026 had smoke coming from their right engine. The captain elected to stop the aircraft on the taxiway and request an inspection from the aviation rescue and fire-fighting (ARFF) services.

Figure 1: Aircraft ground track at Melbourne Airport

Source: Google earth, annotated by ATSB

The ARFF vehicles arrived in front of the aircraft on Taxiway A and an ARFF officer communicated their observations of the right engine to the SMC. The SMC directed the flight crew to monitor the frequency in use by the ARFF. Consequently, the flight crew heard the ARFF officer report to the SMC that the smoke they saw ‘appeared to be normal’. The aircraft captain was aware that the aircraft engines can emit smoke from the engine oil system and cross-checked their engine indications. There were no abnormal indications present and therefore the captain elected to taxi the aircraft to their allocated parking bay and conduct a normal shut down with ARFF in attendance. The aircraft was shut down without further incident.

Maintenance fault finding

After the passengers had disembarked, the captain informed one of the company maintenance engineers that smoke had been observed coming from the right engine after landing, but all engine indications were normal. The engineer conducted a general visual inspection of the engine and reported to the captain that there was no obvious sign of a fault. The captain documented the incident in the aircraft technical log and signed-off duty.

During the turn-around inspection, another company maintenance engineer noted that the right hydraulic system was at the refill level. The engineer conducted leak checks on the right hydraulic system and found a damaged hydraulic hose in the right engine pylon hydraulic bay (Figures 2 and 3). The damaged hose was located downstream of the right engine thrust reverser stow line.

Figure 2: Location of aircraft hydraulic systems and leak

Source: Boeing, annotated by ATSB

Figure 3: Location of hydraulic hose

Source: Boeing

Flight data recorder

The engine thrust reversers are electrically controlled, but hydraulically powered systems. The right hydraulic system powers the right engine thrust reverser and the left system powers the left engine thrust reverser. Flight data recorder information indicated that the three hydraulic systems were at the same quantity when the aircraft landed. When the thrust reversers were applied to assist braking, the left and right hydraulic system quantities reduced, as required, to power the thrust reverser actuators. However, when the thrust reversers were stowed only the left hydraulic system returned to the normal quantity. The right system quantity continued to reduce, which was consistent with a leak in the hydraulic system.

Aircraft manufacturer findings and recommendations

The failed hose was part of the thrust reverser retraction circuit and is otherwise isolated during flight. The thrust reverser circuit is the only location where this part is installed on the aircraft. Boeing note that the leak has previously been observed either as drip from the aft fairing of the engine pylon after flight, or during landing as a mist sprayed from the engine exhaust during thrust reverser retraction. Boeing has advised operators to heighten their awareness of the issue, and in the event of an observed leak at the aft pylon fairing module, to check the incident part number hose for a rupture. Boeing has recorded several in-service failures of this part number hose and investigated the fault with the part manufacturer.

Engine manufacturer findings

During development testing of the engine, the manufacturer, Rolls Royce, identified the potential for a visible white-coloured mist from the engine oil breather to occur at any stage of engine operation. They stressed that this is a normal characteristic of the engine, which is a result of incomplete air/oil separation, and ‘does not represent an increase in engine oil consumption.’

Aircraft captain comments

The captain noted that during the inspection from the ARFF services, the flight crew were asked by the SMC to monitor the ARFF frequency, but they were not allocated a discrete frequency for communications with ATC. This resulted in interruptions from other traffic using Ground frequency for routine communications and at times the captain felt they could not immediately relay information to ATC.

Airservices comments

Airservices noted the captain’s comment regarding the need for a discrete frequency. This is currently not standard practice and has the potential to create confusion for ATC at times of high workload. The use of a published frequency can aid in situational awareness for other operators and ARFF services throughout the emergency.

Safety analysis

Hydraulic leak

During the turn-around inspection of the aircraft, the right hydraulic system fluid level was found to be low due to a ruptured hydraulic hose. This hydraulic hose is only installed in the engine thrust reverser retraction circuit and is otherwise isolated inflight. The flight data indicated that the reduction of fluid in the right hydraulic system, consistent with a hydraulic fluid leak, coincided with the thrust reverser retraction after landing.

Engine smoke

At the time that the aircraft stopped for a visual inspection by ARFF, what was reported as smoke appears to be mist emanating from the vicinity of the engine oil breather (Figure 4). The presence of mist is consistent with the Boeing investigation into the failures of the affected hydraulic hose that indicates a rupture of this hose. However, the location of the mist suggests the source could have been (by itself or in addition to the hydraulic fluid) due to the engine oil breather. This is because the mist was also consistent with what Rolls Royce had previously noted as a visible white-coloured mist that can be observed emanating from the engine oil breather as a result of incomplete air/oil separation.

Figure 4: Aircraft stopped for inspection

Source: Melbourne Airport

Findings

These findings should not be read as apportioning blame or liability to any particular organisation or individual.

• The hydraulic hose in the right engine thrust reverser retraction circuit ruptured when the right engine thrust reverser was retracted on landing.
• The reported engine smoke was probably mist from the right hydraulic system leaking hydraulic fluid into the engine exhaust, or mist from the engine oil breather as a result of incomplete air/oil separation, or a combination of both conditions.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Aircraft manufacturer

As a result of this occurrence and previous occurrences, Boeing has advised the ATSB they have taken the following safety action:

A ‘capture and control in production’ process was introduced. This process has identified and screened out defective parts. Their own investigation has identified the likely root causes of the failures and identified the population of hoses affected. They have communicated recommended actions to aircraft operators, which describes how to identify and replace potentially affected hoses.

Aircraft Operator

As a result of this occurrence, Scoot Airlines has advised the ATSB they are taking the following safety action:

As per the aircraft manufacturer’s recommendations, a 787 fleet check was conducted, potentially affected hoses identified, and replacement hoses ordered.

Safety message

At each stage during this incident: after the aircraft had landed, when the engineering inspection detected a low hydraulic system fluid level, and subsequently when the manufacturer received the failed part, the exact nature of the problem was unclear. However, at each stage, precautionary action was taken to investigate the problem, which mitigated the risk to the safety of personnel and serviceability of the aircraft.

Short Investigations Bulletin - Issue 55

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.  Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

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1. Coordinated Universal Time (UTC): the time zone used for aviation. Local time zones around the world can be expressed as positive or negative offsets from UTC. Singapore local time is UTC +8 and Melbourne Eastern Standard Time (EST) is UTC +10.

What happened

On 7 September 2016, an Emirates Boeing 777-31HER aircraft, registered A6-EGA, was operating a scheduled passenger flight from Dubai, United Arab Emirates, to Brisbane, Queensland. On board were 22 crewmembers and 308 passengers.

At about 1916 Central Standard Time (CST), the left engine oil quantity started to decrease from 16.4 quarts, stabilising at 2 quarts at 1927, when the aircraft was about 650 km north-west of Adelaide, South Australia, and at flight level (FL) 353.^[1] The flight crew contacted company engineering and operations staff and advised them of the situation.

The flight crew received a left engine low oil engine-indicating and crew-alerting system (EICAS) message and conducted the associated non-normal checklist. At about 1951, the flight crew shut the left engine down (Figure 1).

Figure 1: Flight data plot including oil pressure and engine shutdown

Source: Aircraft operator analysed by ATSB

The flight crew contacted air traffic control, declared a PAN^[2] and conducted a diversion to Adelaide Airport, which was the nearest suitable airport. The flight crew commenced a gradual descent to FL 270, and were subsequently cleared for the area navigation (RNAV) approach to runway 05 at Adelaide. The aircraft landed without incident, and arrived at the parking bay at 2056. There was no damage to the aircraft or injuries to crew or passengers.

A subsequent engineering inspection found the left oil supply line to bearings numbers 4 and 5 had fractured and the associated clamp was broken (Figure 2).

Captain comments

The captain commented that the flight crew managed the situation in accordance with their procedures. The weather in Adelaide was beautiful and the aircraft performed well and handled exactly as it did in the simulator in training.

Engine manufacturer investigation

The manufacturer is investigating the following aspects:

• Turbine centre frame (TCF) Supply Tube 2061M79G02:
• evaluating high cycle fatigue (HCF) capability of the TCF tube when a clamp is separated/broken
• studying tube dynamic behaviour, due to broken clamps and its interaction with external components.
• Numbers 4 and 5 Oil Supply Tube 2034M68G01:
• evaluating effects of missing piston ring and clamp separation on the external hardware
• correlating finite element analysis (FEA) (stress analysis) with event findings
• running analysis to verify integrity of current system.
• Clamp Damage:
• mapping broken clamp findings from operator data and shop inspections
• reviewing installation procedures and design characteristics and their effect.

Figure 2: Fractured oil supply line

Source: Aircraft operator

Safety analysis

The left oil supply line to bearings numbers 4 and 5 fractured, resulting in a loss of oil and oil pressure from the left engine. The flight crew received a left low oil pressure warning and followed the associated checklists, shut down the left engine and diverted the aircraft to Adelaide.

Findings

These findings should not be read as apportioning blame or liability to any particular organisation or individual.

• The oil supply line to bearings 4 and 5 fractured at a welded joint and its support clamp was broken, resulting in an oil leak and therefore low oil pressure and quantity in the left engine.
• Following the receipt of a left low oil pressure warning, the flight crew completed the non-normal checklist, shut down the left engine and conducted a diversion to Adelaide.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following safety action in response to this occurrence.

Aircraft operator

The operator performed a fleet-wide inspection and found no leaks or cracks on any other engine.

Safety message

This incident provides an excellent example of effective crew resource management techniques when faced with an abnormal situation. Additionally, regular proficiency checks in the simulator including scenarios of a single engine failure allow flight crew to respond appropriately in the event of such an occurrence in flight.

Aviation Short Investigations Bulletin - Issue 56

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

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1. Flight level: at altitudes above 10,000 ft in Australia, an aircraft’s height above mean sea level is referred to as a flight level (FL). FL 353 equates to 35,300 ft.
2. PAN PAN: an internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance.

What happened

On the morning of 27 August 2016, a Van’s RV-7 aircraft, registered VH-VTZ, and a Glaser-Dirks DG-400 motor-glider, registered VH-XJZ, were both prepared for flight from Gympie aircraft landing area (ALA), Queensland.

The pilot taxied the motor-glider from the Gympie ALA glider hangars and back-tracked on the grass alongside runway 14 (Figure 1). Before entering the runway strip, the pilot made a radio broadcast on the common traffic advisory frequency (CTAF) 126.7, that they were entering and back-tracking runway 14. On arrival at the runway threshold, the pilot made another broadcast that they were lining-up on runway 14. The pilot taxied the motor-glider onto the threshold of runway 14 and conducted their engine run-up checks. After about 10–15 seconds, they made a broadcast that they were rolling on runway 14 and released the brakes for take-off.

At about the same time as the motor-glider was backtracking runway 14, the pilot of the RV-7 made a broadcast on the CTAF that they were taxiing from the general aviation hangars. At the runway holding-point, the pilot then made a broadcast that they were entering and back-tracking runway 14 (Figure 1). Neither pilot heard the broadcasts from the other pilot.

The motor-glider started the take-off roll from the threshold of runway 14 and as it approached take-off speed, the pilot noticed the top of another aircraft (RV-7) appear on the horizon. Both pilots applied their aircraft brakes and veered to their right. The aircraft came to a stop next to each other on the runway abeam the glider hangars at about 1110 Eastern Standard Time (EST). The pilots performed a radio check and verified they could hear each other and both were broadcasting on the CTAF 126.7. They then proceeded on their planned flights without further incident.

Gympie runway slope

From the runway 14 threshold, runway 14 slopes upward to a crest, which is in line with the glider hangars (Figure 1). Runway 14 then slopes downhill to the threshold of runway 32. The motor-glider pilot commented that in an aircraft low to the ground, such as a glider, stationed at the threshold of runway 14, the pilot would not be able to see an aircraft such as the RV-7, back-tracking runway 14, until the other aircraft was abeam the glider hangars (Figure 1). The RV-7 pilot commented that when back-tracking runway 14 in their aircraft they cannot see another low profile aircraft, such as a glider, until they are about 300 m from the threshold of runway 14.

Aircraft radios

The RV-7 has one radio antenna located on the underside of the aircraft. The motor-glider pilot was unsure of the location of their radio antenna, because they are integral to the airframe in order to minimise drag. Both aircraft radio systems are capable of monitoring two frequencies, but can only broadcast on one. Both pilots confirmed they had 126.7 CTAF set and in use as their active frequency at the time of the serious incident. However, the RV-7 pilot commented that their radio microphone may not have been up against their mouth, which would have reduced the volume of their transmissions.

Figure 1: Gympie ALA and ground tracks of the aircraft

Source: Google earth, annotated by ATSB

Previous incidents

Both pilots commented that there have been previous incidents of traffic conflicts between aircraft, which started with missed radio calls when the aircraft were at opposite ends of the main runway (runway 14/32). On these previous occasions, aircraft airborne in the circuit could hear the radio calls of opposite end traffic on CTAF, despite the traffic on the ground not hearing each other.

A search of the ATSB notifications database indicated that in 2016 there were two incidents at Gympie ALA, where the reporter has indicated that a broadcast was either not made, or not heard. It is unknown if terrain shielding contributed to these events.

ATSB comment

The ATSB notes that it is reported that traffic at Gympie ALA is increasing and therefore exposure to the risk presented in this report is increasing. Despite the fact that both pilots made all the required radio calls for their planned operation, a runway conflict occurred. There is currently no reference to the potential for terrain shielding of radio calls in the Gympie ALA Enroute Supplement Australia entry.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

RV-7 pilot

As a result of this occurrence, the pilot of the RV-7 has advised the ATSB that they are taking the following safety action:

Radio checks

The pilot of the RV-7 indicated they would introduce a radio check broadcast, when circumstances permit, during their start checks to verify their transmission volume and readability.

Aerodrome Operator

As a result of this occurrence, the Gympie Aerodrome Operator has advised the ATSB that they are taking the following safety action:

Enroute Supplement Australia

The Gympie Aerodrome Operator indicated they intend to add a note to the Gympie entry in the Enroute Supplement Australia, under ‘Additional Information’, to advise pilots that poor radio propagation between aircraft operating on the ground at opposite ends of the main runway may be experienced.

Safety message

A potential accident was avoided by the actions of both pilots who responded to the presence of the other aircraft by braking and veering to the right. Rather than continuing their flights with the assumption the other made a mistake, they performed a radio check with each other to verify there was no fault with their respective aircraft radios.

Aviation Short Investigations Bulletin - Issue 54

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

Safety summary

What happened

On 7 September 2016, the pilot of a Jabiru J170-C aircraft, registered 24-5215, approached to land, or perform a ‘touch-and-go’ manoeuvre, on runway 09 at Yarram aerodrome, Victoria, as part of a solo training flight. The pilot mishandled the landing attempt and lifted off to perform a go-around. The aircraft was observed at 50 to 100 ft above the aerodrome in a left wing down 30° angle of bank prior to it entering a steep descent consistent with an aerodynamic stall. The aircraft collided with the terrain and the pilot was fatally injured.

What the ATSB found

The ATSB found that the aircraft was likely subject to mechanical turbulence at the threshold of runway 09 at Yarram aerodrome. Trees and hangars on the north-eastern perimeter of the aerodrome were known locally to cause turbulence in the last 50 ft of the approach when the wind gusted out of the east-northeast. This information was not published in the Airservices Australia En Route Supplement Australia entry for Yarram aerodrome. The pilot was also likely affected by physical and mental fatigue given their age, medical history and recent physical labour. Fatigue’s effect on attention, reaction time, and vigilance likely exacerbated the pilot’s mishandling of the landing attempt and the subsequent go-around.

Safety message

Pilots and flying school operators should ensure they have thorough knowledge of the effects of weather on the pilot’s destinations and plan accordingly prior to flight. They should also remain cognisant of the effects of fatigue on the individual at different stages of their life. All pilots need to take into account how lifestyle changes, age, medical history, and medication may affect their fatigue.

The occurrence

At about 1333 Eastern Standard Time on 7 September 2016, a Jabiru Aircraft Pty Ltd J170-C, registered by Recreational Aviation Australia (RAAus) as 24-5215, departed from Tooradin aerodrome, Victoria. The aircraft contained the pilot only.

The pilot planned to fly from Tooradin to the Latrobe Valley airport, Fish Creek, Yarram, Foster and then back to Tooradin as part of obtaining an RAAus solo cross-country navigation certificate endorsement. The endorsement syllabus required that the pilot perform either a full stop landing or conduct a ‘touch-and-go’^[1] manoeuvre at Latrobe Valley airport and Yarram aerodrome. The pilot landed at Latrobe Valley at 1421 and stayed on the ground for about 25 minutes before proceeding with the flight.

At about 1544, the aircraft approached runway 09^[2] at Yarram aerodrome, Victoria. A witness, who was also the Yarram Aerodrome Reporting Officer (ARO) and a pilot, was positioned about 0.7 km west of the accident site. The witness first heard and then saw the aircraft on final approach to runway 09 when it was about 500 m from the runway and at a height of about 300 ft. The witness stated that at this point, the aircraft and engine were both operating normally.

At that time, the witness was outside of their house in front of a machinery shed and adjacent to a shearing shed. The witness then walked into the shearing shed and, approximately 20 seconds later, heard a short application of power from the aircraft, like a ‘quick burst’. The witness thought that the pilot was possibly having some issues at the runway threshold as easterly and northerly winds may result in mechanical turbulence (refer to section titled Yarram aerodrome – Mechanical turbulence). On hearing the throttle ‘ease up’, the witness thought that the pilot must have decided to land further along the runway.

Subsequent examination of the dirt runway 09/27 showed marks where the aircraft attempted to either land or perform a ‘touch-and-go’. The first marks showed that both main wheels touched down about the same time, about 4 m to the left of the centre line. The aircraft then travelled on the right main wheel for about 54 m bouncing from the runway three times, missing runway cones and lights denoting the beginning of the landing area. The aircraft then rolled left and travelled on the left main wheel for 1.4 m before levelling out onto both main wheels, again bouncing, and then striking the lower empennage fairing once. The aircraft rolled right and travelled on the right main wheel for about 3.7 m, again striking the lower empennage prior to lifting off. During that sequence, the aircraft travelled about 96 m and about 15° to the left of the runway centre line. Neither wing tip nor nose wheel contacted the runway. In total, the aircraft bounced about eight times.

Following the quick power burst, the witness then looked out of the shed window and observed the aircraft in the air, away from the runway centreline in a 30° left angle of bank. The witness estimated the aircraft to be 50-100 ft above the ground. The aircraft continued to the left and the bank angle increased. The lower wing then dropped and the aircraft descended in a near to vertical attitude. The aircraft had turned 180° from the original flight path. The witness then lost sight of the aircraft as it went behind the trees at the western end of the aerodrome boundary, but they heard the aircraft impact the ground (Figure 1).

Figure 1: Overhead view of Yarram aerodrome incorporating runway 09/27 with the ATSB assessment of post lift-off flight path, runway markings, pertinent landmarks, wind direction, barriers pertinent to mechanical turbulence and wreckage site

The witness called out to their spouse, a registered nurse, and they drove to the aerodrome. The witness rang the emergency services on the way. Once at the site, they removed the pilot from the aircraft and began providing medical assistance while waiting for the emergency services to arrive. The pilot died from the injuries sustained in the accident. The aircraft was destroyed.

Personnel information

General information

The pilot held a valid RAAus Pilot Certificate, issued on 21 May 2013, and maintained the required medical standard. The pilot’s logbook included the following endorsements: human factors, high performance, nose wheel, passenger carrying, and RAAus flight radio.

The pilot’s logbook showed a total flying experience of 191.4 hours to the last recorded flight on 4 July 2016. The pilot’s total flying experience on the Jabiru J160 and J170 was 75.5 hours and 102.8 hours respectively. In the previous 90 days, the pilot had flown a total of 10.3 hours. The logbook also recorded 174 landings since July 2013.

Pilot training and experience

The pilot’s initial training took longer than the minimum 20 hours required, however, the pilot was reported as being conscientious and passionate. The pilot’s instructors stated that the pilot had been focussed on the cross-country endorsement for the previous two months and had successfully completed two navigation flights with an instructor. The pilot was considered competent to conduct the solo navigation flight and was reportedly very good at self-assessment and aware of their capabilities.

Two years prior to the occurrence, the pilot was involved in a landing accident at Tooradin aerodrome. When on final approach to runway 22, the Jabiru J170’s airspeed decayed and the aircraft stalled from a height of about 20 ft above ground level. The aircraft descended and when contacting the ground, the pilot applied full power and the aircraft bounced. The aircraft then yawed left and the left wing contacted the ground. It then rolled right, the nose contacted the ground, and continued rolling onto the right wing. The aircraft settled down onto the nose. The aircraft sustained substantial damage to the wings and fuselage. At that time, the wind was from the south-west at 5 kt and the pilot’s total flying experience was 125.2 hours, of which 100 hrs was on the Jabiru.

Go-arounds and turbulence

The pilot had conducted a considerable number of go-arounds and was considered ‘pretty good’. The instructor was confident that the pilot would make the appropriate decisions if an approach was unsuitable. The instructor also noted that when close to the runway, the Jabiru, like any high wing aircraft of a similar design, had a tendency to pitch-up when full flap and throttle were applied. Forward pressure on the control stick would have to be used to counteract this tendency. The pilot had practiced go-arounds in this configuration, and had also practiced crosswind circuits and go-arounds. Crosswinds at Tooradin were commonly experienced. The instructor reported that they had not experienced much turbulence at Yarram, but had so at Tooradin. After practice, the pilot handled the turbulent conditions well and had done a considerable number of circuits at Tooradin.

Recent history

On 4 September and 5 September, the pilot had slept from about 2100 until 0700, however, the sleep was reportedly disrupted due to the pilot being sore and tired due to physical labour. On 6 September, the pilot rested for the navigation endorsement flight the next day. The pilot reportedly went to bed at about 2100 and woke at 0700 on 7 September having slept well.

Medical information

Upon initial application as a student pilot with RAAus, the pilot signed the annual medical declaration on 3 December 2011. By signing the form, the pilot was affirming that their health was of a standard equivalent to that required for the issue of a private motor vehicle. On the date of the accident, the pilot held a current and appropriate medical authorisation.

The pilot had reportedly suffered from chronic pain and sleep issues for a number of years, including sleep apnoea. The pilot had had a major illness in the past and, at the time of the accident, was 72 years of age.

Aircraft information

The Jabiru Aircraft Pty. Ltd. J170-C is a two-seater, fibre-reinforced, light sport aircraft with a high wing and tricycle undercarriage. The aircraft was first registered on the RAAus aircraft register on 11 January 2007 and at the time of the occurrence, was fitted with a Jabiru 2200B 4-cylinder engine.

Meteorological information

The Bureau of Meteorology provided data recorded by the automatic weather station at Yarram. At the time of the occurrence (1544), the wind was from 080° at 13 kt gusting to 18 kt. This would have resulted in about a 5-7 kt left crosswind and a 12-17 kt headwind.^[3]

Yarram aerodrome

Yarram was a registered aerodrome^[4] maintained by the Wellington Shire Council. The aerodrome had two runways, runway 05/23 and runway 09/27. Runway 09/27 was constructed of yellow granitic sand and was 756 m in length. At the time of the accident, runway 05/23, a grass runway, was not in use due to surface water.

Mechanical turbulence

Any obstruction to the wind flow, including buildings and trees, can produce disturbed air that can manifest as mechanical turbulence. The intensity of mechanical turbulence is largely dependent on the wind speed, surface roughness, and atmospheric stability. The intensity increases as the wind speed and surface roughness increases, and when the airflow is forced by obstacles to diverge around, or converge through, gaps in barriers. For example, the Bureau of Meteorology (1988) stated that large scale disturbances to airflow may occur when strong winds strike a mountain range or large hill. Likewise, sometimes moderate winds of 15-20 kt may significantly disturb the airflow.

It was reported that mechanical turbulence due to trees and hangars on the north-eastern perimeter of the aerodrome could be experienced when operating on runway 09 (Figure 1). This occurred when there was a north-easterly wind, and could catch pilots by surprise, particularly if they were not expecting it.

A representative from the Yarram Aero Club stated that when landing on runway 09, turbulence could be experienced from about 50 ft and then, when at 10 ft, ‘things would be moving around quite a bit’. The representative also recommended that new users to the aerodrome should contact the ARO to ascertain the conditions. They also suggested a note in the Airservices Australia En Route Supplement Australia (ERSA) may bring attention to this phenomenon.

Radio broadcasts

The pilot had been trained on the use of the radio and was aware of the inbound and circuit broadcasts required when approaching an aerodrome. When departing from Tooradin, the pilot broadcast a departure call. However, the pilot did not make the required calls on the Yarram common traffic advisory frequency.^[5] Examination of the aircraft post-accident found ‘post-it’ notes on the pilot’s flight plan with a script of the call and the required frequency showing the pilot had intended to make the calls.

Operational information

Flight route

The pilot was conducting a solo navigation exercise from Tooradin to the Latrobe Valley airport, Fish Creek, Yarram, Foster and return to Tooradin requiring that they conduct either a full stop landing or a ‘touch-and-go’ manoeuvre at Latrobe Valley airport and Yarram aerodrome. A review of the data from a handheld GPS device recovered from the aircraft showed that the actual flight route was similar to that planned. However, the track from Latrobe Valley was more consistent with overflying Foster Township rather than Fish Creek Township (Figure 2). The aircraft then tracked around the mountain ranges to Yarram.

Figure 2: Google earth image overlayed with the aircraft’s actual flight route on the leg from Latrobe Valley to Yarram downloaded from the recovered handheld GPS unit bypassing Fish Creek – a required navigation point for the solo navigation exercise.

Source: Google earth, modified by the ATSB

Wreckage examination

On-site examination of the wreckage found that:

• the aircraft travelled about 200 m from the lift-off point on the runway to where it came to rest
• the aircraft collided with terrain in a left wing and nose down attitude
• the wreckage trail was relatively short signifying a low speed, high angle of attack impact into soft muddy terrain
• the wing flaps were in the full down position (as appropriate for landing or for a go-around from final approach)
• the fuel quantity at the time of the accident could not be established due to the left wing and left-wing fuel cap being separated from the fuselage, however, the aircraft had a significant quantity of fuel in the right wing
• debris was identified in the throat of the engine’s carburettor venturi, but these substances may have been sucked into the venturi during the accident sequence
• fragments of the propeller were found displaced radially about 10-15 m either side of the wreckage.

The debris in the venturi, radial distribution of propeller fragments, as well as the distance the aircraft travelled after becoming airborne from the runway were all consistent with an engine producing thrust prior to the aircraft colliding with terrain.

Subsequent engine and instrumentation examination performed by the ATSB found no evidence of an engine, airframe or mechanical failure that may have contributed to the accident.

During the engine examination, the ATSB found that the aircraft’s engine had been replaced and had recently had an overhaul completed. However, the aircraft’s maintenance logbook did not state when the engine was certified and installed into the aircraft.

The aircraft maintenance logbook’s instruction page stated that where components were installed, removed, or replaced, complete details were to be recorded in Part 3 – modification and component change record. The RAAus technical manual stated that component changes must be recorded in the maintenance logbook and the logbook must have a section for this record titled ‘Modification and Components Record’. The logbook did have the appropriate section, however, a sheet for recording weight and balance changes had been pasted over it and component changes could not be recorded in this part.

The ATSB also found anomalies with the manufacturer’s instructions regarding certain aspects of the engine overhaul in their overhaul manual. These were subsequently identified and rectified by the manufacturer and no further action has been deemed necessary by the ATSB.

__________

1. Practice landing in which the aircraft is permitted to touch the runway briefly; in many cases, flaps are moved to the take-off setting while the aircraft’s weight is on the wheels.
2. Runways are named by a number representing the magnetic heading of the runway.
3. The Jabiru J170-C pilot operating handbook (Section 3.3) stated that the maximum allowable crosswind velocity was dependant on pilot capability and aircraft limitations. With average pilot technique, direct crosswinds of 14 kt could be handled safely.
4. www.casa.gov.au/aerodromes/standard-page/aerodrome-categories-under-casr-part-139
5. A common traffic advisory frequency is the frequency on which pilots operating at a non-controlled aerodrome should make positional radio broadcasts.

Safety analysis

Introduction

While landing on runway 09 at Yarram aerodrome, the pilot of Jabiru Aircraft Pty Ltd J170-C, 24‑5215, was unable to effect a safe landing, or ‘touch-and-go’ manoeuvre. The pilot then attempted to go-around but was unable to prevent a departure from controlled flight at low altitude. The departure from controlled flight was consistent with the aircraft entering an aerodynamic stall prior to colliding with terrain. This analysis will consider factors that potentially contributed to the accident.

Mishandled landing, go-around and subsequent aerodynamic stall

Examination of runway 09/27 shortly after the accident revealed aircraft tyre and empennage strike markings that indicated that the pilot had inadvertently mishandled an attempt to either land the aircraft or perform a ‘touch-and-go’ manoeuvre. The aircraft initially touched down on both main wheels but was 4 m to the left of the runway centreline, at a heading of 15° into the wind. The aircraft bounced and rolled on either one or both main wheels for approximately 96 m incurring two rear empennage strikes prior to lifting off. It is likely that the pilot was initially attempting to correct the landing or ‘touch-and-go’ attempt but then decided to lift off and go-around.

About this time, the witness heard the pilot apply a brief ‘burst’ of power and then saw the aircraft airborne at 50-100 ft height and in a left wing down 30° angle of bank. The aircraft continued to bank to the left prior to the left wing dropping, with the aircraft entering a nose down steep descent and then colliding with terrain.

Mechanical turbulence

The witness and other pilots with experience of the conditions at Yarram stated that, when approaching runway 09 with the wind from the north-east at between 10-15 kts, the final 10 ft prior to landing could be quite turbulent and become ‘a handful’ for an unaware or inexperienced pilot. It is likely that, given the conditions on the day, the aircraft was subject to mechanical turbulence at the threshold of runway 09. In addition to the pilot’s fatigue and level of experience (see below), it is likely this has resulted in the mishandled landing or ‘touch-and-go’ attempt.

At the time of the occurrence, the Airservices Australia’s En Route Supplement Australia did not indicate that a hazard such as mechanical turbulence could be experienced at Yarram aerodrome. Other locations such as Katoomba and Canberra specifically mention ‘turbulence and wind shear during winds above 15 kt’ and ‘during strong westerly winds TURB may be experienced in touch down area LDG RWY 35’ in the ‘Additional information’ sections. Highlighting the risk of an aircraft encountering mechanical turbulence during times when gusty north-easterly wind conditions are present could reduce the risk of a mishandling event during a critical phase of flight. It was unknown if the pilot was aware that these conditions could exist at Yarram.

Fatigue and experience

Researchers have stated that fatigue leads to lapses in attention, slowed reaction times, and reduced vigilance that can result in individuals overlooking or skipping tasks or parts of tasks. Researchers have also stated that older individuals still require the same amount of sleep as younger individuals but tend to get less due to increased nighttime awakenings. The decline in nightly sleep is accompanied by increased daytime fatigue (Battelle Memorial Institute, 1998). Researchers have also found that chronic pain is biologically linked to fatigue and 75 per cent of people with chronic musculoskeletal pain report having fatigue (University of Iowa, 2008).

The pilot was past retirement age and had a history of health and chronic pain issues including sleep apnoea. It was reported that the pilot had slept well leading up to the accident flight but had been physically fatigued through outdoor labour two days prior. There were a number of indicators of fatigue effecting the pilot’s performance, including not continuing to the Fish Creek navigational point, as well as neglecting to make a radio call on approaching Yarram aerodrome despite reminders in the cockpit to make the call and of the appropriate radio frequency.

Researchers have stated that experienced individuals will often make better decisions than inexperienced individuals due to their ability to recognise similar situations they have been in before and diagnose appropriate actions required to overcome problems quicker. They also state that an experienced individual will often be able to expend less cognitive effort in decision making as they do not need to do as much option evaluation as a novice, and thus will not experience as much decision, or cognitive, fatigue. The higher cognitive effort an inexperienced individual needs to solve a problem may further exacerbate the effects of any fatigue they may be experiencing (Wickens, Hollands, Banbury and Parasuraman, 2013).

The pilot did not have a great deal of flying experience given that they had recorded 191 hours total flying over a five-year period. This was their first solo cross-country navigation flight and the pilot had experienced an accident in a landing situation two years prior. It is likely that the pilot’s inexperience would have exacerbated the effects of the fatigue felt as discussed.

It is likely that, once the aircraft had been affected by mechanical turbulence, fatigue and experience level have led to the pilot’s inability to correct the aircraft’s departure from a controlled landing and controlled flight in time to prevent an aerodynamic stall and collision with terrain.

Aircraft maintenance logbook

During the engine examination, it could not be established when the accident aircraft’s engine had been certified and installed into the aircraft as this component change had not been recorded in the aircraft maintenance logbook. This action, while not contributing to the accident, increased safety risk as not recording component changes (such as the removal and installation of an engine) can result in an inability to trace changes to an aircraft’s life-limited components.

Findings

From the evidence available, the following findings are made with respect to the collision with terrain involving a Jabiru Aircraft Pty. Ltd. J170-C, Recreational Aviation Australia aeroplane, registered 24-5215, at Yarram aerodrome, Victoria on 7 September 2016. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• Upon reaching the threshold of runway 09 at Yarram aerodrome, the aircraft was likely subject to mechanical turbulence resulting in the mishandling of the landing or 'touch-and-go' attempt.
• The pilot inadvertently mishandled the subsequent go-around leading to the aircraft's low altitude aerodynamic stall and collision with terrain.

Other factors that increased risk

• Fatigue and level of experience likely affected the pilot's ability to respond to the demands required to correct the aircraft's departure from controlled flight during the landing attempt and subsequent go-around.
• While locally known, the En Route Supplement Australia entry for Yarram aerodrome did not highlight the risk of an aircraft encountering mechanical turbulence on runway 09 during the gusty wind conditions present on the day, increasing the risk of a mishandling event during a critical phase of flight.
• The aircraft’s maintenance logbook did not state when the engine was certified and installed into the aircraft resulting in an inability to trace changes to its life-limited components.

Safety issues and actions

Proactive safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

The Wellington Shire Council, as the operator of the Yarram Aerodrome, initiated an entry into the En Route Supplement Australia entry for Yarram aerodrome highlighting the risk of an aircraft encountering mechanical turbulence on runway 09 during the gusty wind conditions present on the day of the accident. In a letter dated 29 June 2017, Wellington Shire Council informed the ATSB that:

The draft report has identified mechanical turbulence as a risk factor which Council was not previously aware existed at Yarram Aerodrome. Council has initiated a new entry in ERSA in line with the draft report.

Processes for updating aeronautical information publications have also been examined and changes made whereby the aviation community will be formally consulted in the review and amendment of publications.

Sources and submissions

Sources of information

The sources of information during the investigation included the:

• Yarram aerodrome reporting officer
• Vice President Yarram Aero Club
• Wellington Shire Council
• Tooradin Flying School
• Jabiru Aircraft Pty Ltd
• Latrobe Valley Aero Club and Flying School
• Civil Aviation Safety Authority
• Recreational Aviation Australia
• Victorian Police Coronial Support Unit
• Victorian Police Force
• Bureau of Meteorology
• Directorate of Defence Aviation and Air Force Safety.

References

Battelle Memorial Institute (1998). An Overview of the scientific literature concerning fatigue, sleep, and the circadian cycle. Report prepared for the Office of the Chief Scientific and Technical Advisor for Human Factors, US Federal Aviation Administration.

Bureau of Meteorology. (1988). Manual of meteorology, part 2: Aviation meteorology. Canberra: Department of Administrative Services.

University of Iowa. (2008). Biological link between pain and fatigue discovered. ScienceDaily. Retrieved January 17, 2017 from 

Wickens, C.D., Hollands, J.G., Banbury, S. and Parasuraman, R. (2013). Engineering psychology and human performance (4th Edition). Abingdon, UK: Routledge.

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act 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 next of kin, the Yarram aerodrome reporting officer, chief flying instructor, flying instructor and Level 2 maintainer at Tooradin Flying School, Wellington Shire Council, the aircraft manufacturer, the coroner’s representative, Recreational Aviation Australia and the Civil Aviation Safety Authority.

Submissions were received from the next of kin, the Yarram aerodrome reporting officer, Wellington Shire Council, the aircraft manufacturer, Recreational Aviation Australia and the Civil Aviation Safety Authority. 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 2017 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

What happened

On 5 September 2016, at about 0737 Central Standard Time (CST), a Cessna 441 aircraft, registered VH-NAX (NAX), departed from Adelaide Airport on a charter flight to Coorabie aircraft landing area (ALA), South Australia. On board were the pilot and nine passengers.

At about 30 NM from Coorabie, the pilot of NAX broadcast on the common traffic advisory frequency advising that they were inbound to the aerodrome. The pilot of another aircraft operated by the same company, that had landed some minutes earlier on runway 14 at Coorabie ALA, responded to the broadcast, advising the pilot of NAX to use runway 32 due to the downwards slope on runway 14 (Figure 1). The pilot of NAX had not previously operated into Coorabie ALA, but had studied prior to the flight the information provided by the operator (see Pilot hazard awareness below) with respect to any hazards associated with their landing. In addition, as the other company aircraft had landed safely, they elected to conduct a straight-in approach to runway 32. The pilot then positioned the aircraft on about a 10 NM final to runway 32.

Figure 1: Coorabie ALA facing south

Source: ALA operator

At about 0900, when the aircraft was on final approach to runway 32, the pilot reported that the aircraft decelerated suddenly (from about 120 to 110 kt). At the same time, there was a slight shudder of the right engine and a change in the sound of the propeller pitch. The pilot immediately increased the power to both engines and levelled the aircraft off. The pilot checked the engine instruments and the annunciator panel, and there were no abnormal indications.

The pilot then conducted a go-around and a left circuit at about 1,100 ft above ground level. The aircraft subsequently landed on runway 32. While back-tracking, the pilot sighted a power pole on a hill beyond the runway 32 threshold (in the direction from which the aircraft had just approached). After shutting the aircraft down, the pilot noticed damage to the right propeller blades and suspected that the aircraft had struck a powerline (Figure 2). Witnesses on the ground confirmed that they had seen and heard the aircraft strike the powerline.

The pilot and passengers were not injured. The aircraft sustained minor damage.

Figure 2: Coorabie ALA showing the powerline 370 m from the threshold

Source: ALA operator

Pilot comments

The pilot of NAX had planned to overfly the runway, inspect the landing area and then join the circuit on the downwind leg for runway 14. The pilot commented that if they had overflown the airstrip prior to commencing the approach, they may still not have identified the powerline as the poles and wire were difficult to see. There was one pole near a house and the next pole was some distance away on terrain rising from the runway threshold. The company pilot who had landed before NAX did not sight the powerline during their strip inspection (overflying the runway).

The pilot further commented that if they had conducted a steeper approach they may not have struck the powerline.

Pilot hazard awareness

The pilot reported that they had not been alerted to the presence of the wire before operating at the aerodrome. The pilot had reviewed the company strip guide information for Coorabie ALA and photos of the runway provided by the aerodrome operator.

The information provided included a sketch of the runway and its direction (14/32), the latitude and longitude, length (900 m), width (25 m), elevation (75 ft) and under Special procedures: ‘Slight rise to NW end Small hill’.

Wire marking standards

The requirements for mapping and marking powerlines and their supporting structures were published in Australian Standard AS 3891.1, Part 1, Permanent marking of overhead cables and their supporting structures and AS 3891.2, Part 2, Marking of overhead cables for low level flying. The ALA was not used as described in Clause 3.2 of AS 3891.1 nor were the powerlines in an area involved in planned low-flying operations as described in AS 3891.2. The powerlines did not require marking in accordance with either Australian Standard.

Advisory material

The Civil Aviation Advisory Publication (CAAP) 92-1(1) Guidelines for aeroplane landing areas, provided guidance on how pilots may determine the suitability of an aeroplane landing area (ALA) such as the recommended obstacle clearance standards and suggested landing area markings. The CAAP defined an obstacle free area to mean ‘there should be no wires or any other form of obstacles above the approach and take-off areas, runway, runway strips, fly-over areas or water channels’. The minimum landing area physical characteristics recommended in the CAAP for aircraft (other than single-engine and centre-line thrust aeroplanes not exceeding 2,000 kg maximum take-off weight) for day operations is depicted in Figure 3. This shows the approach and take-off area should be clear of wires within 900 m of the runway ends above a 5 per cent (3°) slope.

Figure 3: Recommended landing area characteristics

Source: Civil Aviation Safety Authority

Powerline

The powerline was located about 370 m from the runway threshold and about 7.5 m above ground level. The powerline was below the recommended slope gradient of 5 per cent (Figure 3).

The operator of the ALA reported that they had spoken to a representative from the aircraft operator and advised them of the existence of the powerline prior to the flight. The ALA operator had identified the powerline as a hazard and reported that they had requested the infrastructure provider to fit markers to the powerline about 12 months prior to the incident.

The power insfrastructure provider advised the ATSB that the ALA operator had enquired with the then distribution licensees about the fitting of markers to the powerline in 2012 and 2015. In 2012, the distribution licensee investigated and determined that the span of the powerline was too long to take the additional load of the markers. In 2015, the request for the markers was raised again by the ALA operator in conjunction with a request for a quote on a transformer upgrade. There was no follow-up with the provider about these requests.

Runway illusions

The profile of Coorabie ALA runway 32 and the approach area of 900 m (based on the recommended dimensions specified in Figure 3), obtained from Google earth, is depicted in Figure 4. The cleared area commencing from the runway threshold was about 1,170 m in length. Along that length, the profile rose from 9 m (30 ft) to 22 m (72 ft) elevation at the nominated runway length of 900 m, with higher ground rising to about 29 m (90 ft) beyond 900 m. The information provided to the operator by the ALA operator was that the runway length was 900 m, suggesting that the rising terrain beyond that point was not part of the runway. The stated runway elevation was 75 ft (23 m).

As can be seen in Figure 4, the terrain at the powerline was about the same height as the runway 32 threshold, with a dip in between. The glide path from a powerline 7.5 m above the terrain to the runway threshold was about 1°. A normal approach path is about 3°.

Runway slope is one environmental condition that can affect a pilot’s perception of the aircraft’s position relative to a normal approach profile. Flight Safety Foundation Approach and landing accident reduction tool kit briefing note 5.3 – Visual illusions stated that an uphill slope creates the illusion of being too high. That illusion may induce the pilot to ‘correct’ the approach resulting in a lower flight path, or may prevent the pilot from detecting when the aircraft is too low during the approach.

The briefing note advises that to reduce the effects of visual illusions, flight crews should assess approach hazards and be trained to recognise and understand the factors and conditions that cause visual illusions.

Figure 4: Coorabie ALA runway 32 and 900 m approach area profile

Source: Google earth annotated by ATSB

ATSB comment

It is essential for pilots to be aware of hazards prior to operating into an aerodrome. The location of known hazards and obstacles such as powerlines should be included in aerodrome information that is provided to pilots and aircraft operators who are permitted to operate at the airfield. As runway slope can result in visual illusions that may affect a pilot’s judgement of the approach profile, runway slope information should also be included in operational information.

CAAP 166-1(3): Operations in the vicinity of non-controlled aerodromes stated that straight-in visual approaches are not a recommended standard procedure. They can be conducted provided certain conditions are met, including that pilots must be able to assure themselves of the aerodrome’s serviceability and that hazards have been identified.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following safety action in response to this occurrence.

Powerline owner

Following the incident (at the time of repairing the wire), the infrastructure provider marked the wire with three round orange markers (Figure 5).

Figure 5: Powerline with orange markers

Source: ALA operator

Aircraft operator

As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:

Notice to operational crew

The company issued the following directives in a notice to operational crew:

• Operations to new ALAs require specific chief pilot approval.
• ALAs that have not been used by company aircraft for more than 12 months are treated as new.
• All operations to ALAs require an overhead join to check the runway.
• Straight-in approaches to ALAs are not permitted.

Safety message

Research conducted by the ATSB found that 166 aircraft wirestrikes were reported to the ATSB between July 2003 and mid-June 2011 and another 101 occurred and were unreported but identified by electricity distribution and transmission companies. The majority of wirestrike occurrences were associated with aerial agriculture operations, however, 22 occurrences (8 per cent) involved private operations. Further information is in the research report, Under reporting of aviation wirestrikes.

The ability of pilots to detect powerlines depends on the physical characteristics of the powerline such as the spacing of power poles, the orientation of the wire, and the effect of weather conditions, especially visibility.

Depending on the environmental conditions, powerlines may not be contrasted against the surrounding environment. Often the wires will blend into the background vegetation and cannot be recognised. In addition, the wire itself can be beyond the resolving power of the eye: that is, the size of the wire and limitations of the eye can mean that it is actually impossible to see the wire. As such, pilots are taught to use additional cues to identify powerlines, such as the associated clearings or easements in trees or fields that can underlie the powerline, or the power poles and buildings to which the powerlines may connect.

Risks associated with operations to private airstrips can be mitigated by ALA owners assessing their airstrips against the guidance in CAAP 92-1(1) Guidelines for aeroplane landing areas. Such risk assessments would benefit from giving consideration to first time users of the ALA.

ATSB research report An overview of spatial disorientation as a factor in aviation accidents and incidents stated that ‘runway illusions can be mitigated against by pilots being aware of the characteristics of their destination airfield in advance, and by being aware of the potential for such illusions to occur’.

Short Investigations Bulletin - Issue 55

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

What happened

On 4 September 2016, at about 1655 Western Standard Time (WST), an amateur-built Van’s RV-9A aircraft registered VH-KLV (KLV), departed Albany Airport, Western Australia (WA), for a flight to Jandakot Airport, WA. On board the private flight were a pilot and one passenger.

About 15 minutes into the flight, the aircraft was north-west of Mount Barker and climbing through about 4,000 ft. At this time, the pilot observed an oil temperature indication greatly exceeding the normal operating limit, all other engine indications appeared normal. The pilot immediately reduced power to idle and turned the aircraft towards an airstrip to the west of Mount Barker (Figure 1). As the aircraft descended through about 2,500 ft, the pilot assessed that they did not have sufficient altitude to glide to the airstrip. The pilot then elected to conduct a precautionary^[1] landing.

Figure 1: Approximate flight path of VH-KLV

Source: Google maps, modified by ATSB

The pilot identified a section of disused road as suitable to conduct the precautionary landing and positioned the aircraft to make a curving approach to the road. At about 200 ft above ground level, the pilot detected the aircraft becoming low and applied power to continue the approach. The engine responded briefly before losing all power. The pilot identified that they did not have sufficient height to glide to the disused road. To avoid powerlines located next to the disused road, the pilot elected to fly the aircraft into trees.

The aircraft struck the tree canopy and slowed to a near stop before falling onto the disused road. The aircraft landed nose first before overturning and coming to rest inverted (Figure 2). The weight of the aircraft prevented the pilot from opening the sliding canopy. The pilot and passenger exited through the broken windscreen.

The pilot and passenger sustained minor injuries and the aircraft was substantially damaged.

Figure 2: VH-KLV after the accident

Source: Western Australia Police

Pilot comments

The pilot of VH-KLV provided the following comments:

• After the pilot identified the high oil temperature, they prepared for a precautionary landing. They did not consider a forced^[2] landing until the engine failed.
• The pilot advised that when they are flying, they are always looking for places to land as if the engine fails there is only a short time to decide where to land.
• The aircraft is fitted with a four point harness. This worked extremely well and prevented more serious injuries.

Engineering examination

Due to the limited scope of this investigation a post-accident engineering examination was not conducted. The cause of the high oil temperature indication was not determined.

Safety message

This incident highlights the importance of actively managing an emergency situation. The pilot identified the abnormal engine indication and elected to conduct a precautionary landing while the engine continued to develop power. Once an engine malfunction is identified it is important to consider that remaining power may be inconsistent and unreliable.

The US Federal Aviation Administration airplane flying handbook chapter: Emergency procedures provides information on effective management of precautionary and forced landings.

The RV-9A is not an aerobatic aircraft, however, KLV was fitted with a four-point aerobatic type harness. Four-point harnesses provide superior occupant protection during an accident, in particular when an aircraft overturns. The fitment and use of the four-point harness most likely prevented more serious injuries to the occupants.

Aviation Short Investigations Bulletin - Issue 54

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

__________

1. A landing conducted when the pilot considers further flight inadvisable.
2. An immediate landing made when the aircraft engine does not continue to produce power.

What happened

On 19 August 2016, a JetGo Australia Embraer EMB-135LR, registered VH-JTG (JTG), operated scheduled passenger flight JG65 from Tamworth, New South Wales (NSW), to Brisbane, Queensland (Qld). At 2104 Eastern Standard Time (EST), the aircraft began to taxi from parking bay 1 to runway 30 right (30R) with the taxiway and runway lights not activated (Figure 1). At 2107, the captain taxied the aircraft onto the runway and immediately began the take-off run. During the take-off run, at a speed of about 70 knots, the first officer detected the runway lights were not illuminated and activated them using the pilot activated lighting (PAL) (Figure 2). The flight crew continued the take-off.

Figure 1: Taxi path overview (both incidents)

Source: Airservices Australia, modified by ATSB

Figure 2: Take-off run of JTG on 19 August showing runway lights not activated (left) and then activated (right)

Source: Airport Operator

On 28 August 2016, the same aircraft operated scheduled passenger flight JG65 from Tamworth to Brisbane. At 1937, the aircraft began to taxi from parking bay 1 to runway 30R. As the aircraft taxied, the runway and taxiway lights extinguished (Figure 3). The flight crew continued to taxi, lined up on runway 30R and selected the aircraft landing lights on. At 1940, 48 seconds after lining up, the aircraft began the take-off run and departed runway 30R with the runway lights not activated.

No persons were injured, and the aircraft was not damaged in the incidents.

Figure 3: JTG taxiing on 28 August with runway lights illuminated (left) and then extinguished (right)

Source: Airport Operator

Runway and taxiway lighting

The taxiway and runway lighting at Tamworth Airport was controlled by a PAL system combined with an aerodrome frequency response unit (AFRU), known as AFRU + PAL. To activate the lights, pilots were required to transmit a sequence of three transmissions on the common traffic advisory frequency (CTAF). Each transmission was to have a maximum duration of 1 second with the break between transmissions being a maximum of 1 second. On receipt of the appropriate transmission sequence, the airport lights were activated and the AFRU broadcast the automatic message: ‘Tamworth Airport CTAF, runway lighting on’ on the Tamworth CTAF.

Once the AFRU + PAL system was activated, the airport lighting remained on for 30 minutes. If it was reactivated during this period, the lighting would remain on for 30 minutes from the time of reactivation. 10 minutes prior to the end of the 30-minute activation period, the primary wind indicator (windsock) lights commence flashing to warn users that the airport lighting is about to extinguish (Figure 4). In addition, an automated message ‘Tamworth Airport CTAF, lights 10 minutes remaining’ was broadcast on the CTAF to advise 10 minutes of runway lighting remaining.

Figure 4: Flashing primary wind indicator showing the windsock illuminated when the runway lights were active (left) and not illuminated (right)

Source: Airport Operator

On 19 August, at 2039, the AFRU broadcast ‘Tamworth Airport CTAF, lights 10 minutes remaining’, the lights then extinguished at 2049. At 2107, during the take-off run of JTG, the first officer broadcast an AFRU + PAL activation sequence on the Tamworth CTAF and the runway lights illuminated.

On 28 August, at 1928, the AFRU broadcast ‘Tamworth Airport CTAF, lights 10 minutes remaining’, the lights then extinguished at 1938. At 2007, an AFRU + PAL activation sequence was broadcast by another aircraft and the runway lights illuminated.

There was no indication that the AFRU + PAL system was malfunctioning on the nights of the incidents.

Captain comments

The same pilot was operating as captain of JTG during both incidents. The captain provided the following comments:

• The captain did not notice that the runway lights were extinguished during either incident and were not aware until notified after each incident.
• The taxiway lights at Tamworth are of the recessed centreline type. The taxi from bay 1 to runway 30R is over a rise. Therefore, only three to four taxiway lights are normally visible from the point at which you turn onto the taxiway. The captain remarked that the raised type taxiway side lights found at other airports are more easily visible.
• Wind information for pre-flight planning is obtained through the flight crew electronic flight bag or automatic weather information service (AWIS). Therefore, they will only observe the windsock as a back-up, if it is available and close.
• During turn-around between flights, the flight crew do not wear headsets and will not hear the 10 minutes remaining broadcast if it occurs during this time.
• The responsibility for ensuring the airport lighting would be active was not assigned to either flight crewmember. There was no procedure for ensuring the airport lighting would be illuminated for the departure.
• Both incidents occurred at the end of long duty days, so fatigue may have been a factor.

First officer comments – 19 August

The first officer of the 19 August incident provided the following comments:

• The tiller in the Embraer 135 is located on the captain’s side. Therefore, the first officer always acts as pilot monitoring^[1] (PM) during taxi. The taxi from bay 1 to runway 30R is short and a period of intense workload. During this time, the first officer did not look outside the cockpit.
• The first officer did not look outside of the cockpit until the aircraft began moving during the take-off run. Once they looked outside, they immediately felt that something was not right. About five seconds later, the first officer detected that the runway lights were not illuminated.
• The first officer was PM for this flight. As PM, they were able to quickly activate the PAL and resolve the issue, and did not consider aborting the take-off.
• The first officer used the take-off data card for wind information and did not look at the windsock prior to departure.

First officer comments – 28 August

The first officer of the 28 August incident provided the following comments:

• The first officer did not notice that the runway lights were extinguished and was not aware until notified after the incident.
• The primary wind indicator at Tamworth is situated so that it is illuminated by light from the adjacent apron lighting and a red obstacle light is located above the windsock. On subsequent flights to Tamworth, the first officer has observed that this gives the appearance of the windsock being illuminated when the runway lighting is extinguished (Figure 4).

Aircraft lighting

The Embraer 135 is fitted with three landing lights and two taxi lights. The combination of these lights provides a substantial amount of illumination in front of the aircraft.

The taxi lights are used from the beginning of taxi until after departure. Prior to commencing the take-off run, the landing lights are also selected on. The landing lights provide considerably more illumination than the taxi lights.

All flight crew described the aircraft lighting as extremely effective at illuminating the runway ahead of the aircraft and reported no controllability issues during the take-off runs.

Parking apron lighting

Prior to both incidents, the aircraft parked at bay 1 for the embarkation of passengers (Figure 5). This bay is substantially lit by apron floodlights. These lights are not part of the PAL system and remain illuminated when the PAL system extinguishes the runway and taxiway lights.

All three flight crew commented that the apron lighting degraded night-vision and the short taxi from bay 1 to runway 30R did not allow time for eyes to adjust to the dark surrounds of the runway.

Figure 5: JTG parked at bay 1

Source: Airport Operator

Environmental conditions

Last light^[2] on 19 August 2016 occurred at 1757, three hours and ten minutes before the take-off. At 2017, the moon was 19 degrees above the horizon and about 99 per cent visible. There was a clear sky.

Last light on 28 August 2016 occurred at 1802, one hour and 38 minutes before the take-off. The moon was below the horizon and the sky was clear.

ATSB comment

Two different PAL systems exist at Australian airports, PAL and AFRU + PAL. The activation sequence for each system is different.

CTAF recordings for the period surrounding each incident showed multiple unsuccessful attempts by other aircraft to activate the AFRU + PAL using the sequence of transmissions for a PAL system.

AIP ERSA INTRO paragraphs 23.4 and 23.5 detail the differences between the two systems and the correct transmission sequence to activate each system.

While this did not contribute to the incidents, pilots are reminded to be familiar with the identification and use of the different systems.

Safety Analysis

The illumination provided by the aircraft taxi and landing lights made it difficult to detect that the PAL was not activated. Due to the rise on the taxiway, the crew would only have been able to see a few lights ahead of the aircraft, and these would have been illuminated by the aircraft lights. Adding to this, both crew did not have an expectation that the lights may have been extinguished as the cues available did not assist. The auditory 10-minute PAL extinguishing warning could not be heard without headphones, and the windsock flashing light warning was not noticed as the crew obtained wind information using the flight crew electronic flight bag or AWIS.

As the company standard operating procedures did not assign a task of ensuring the runway lights were selected on to a specific role prior to taxi, there was also no procedural prompt to the crew.

The short taxi with a high workload further reduced the chance of detection.

Findings

• The crew did not activate the airport lighting and did not detect that the lighting was off prior to the take-off run.
• Available lighting from the aircraft taxi and landing lights, a lack of crew expectation, a short taxi with high workload, and no assigned role or procedure to check for runway lighting resulted in the crew not detecting the lack of runway lights.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to these occurrences.

Aircraft operator

As a result of these incidents, the aircraft operator has advised the ATSB that they are taking the following safety actions:

Changes to procedures

• When activating the aircraft taxi lights the pilots must ensure that they confirm the status of the PAL.
• When conducting night operations at an unmanned airport, the pilots must activate the PAL or AFRU + PAL by keying the microphone on the appropriate frequency unless the aircraft immediately ahead has already done so. For example, if the aircraft 10 minutes ahead has turned the lights on it will not be necessary to activate the lights again as the lights will normally remain on for a period of 30 to 60 minutes depending upon the installation.
• If no traffic is evident then the pilots must activate the PAL prior to taxi for departure and within 15 nm of the aerodrome and whilst above the lowest safe altitude for arrival.

Safety message

These incidents demonstrate the impact workload stress can have on operations. The short taxi created a high workload situation which impacted on the flight crews’ ability to detect the extinguished runway lighting.

The incident on the 28 August also highlights the hazards associated with change blindness, inattention blindness and expectation bias.

Change blindness occurs when a person does not notice that something is different about the visual environment relative to before the change. Research has shown that in some cases, quite dramatic changes are not detected, particularly if changes occur when the observer is not looking at the relevant part of the visual environment at the time. In this incident the flight crew did not detect the runway lights extinguish during taxi prior to departure.

The Transport Canada article Deadly Omissions includes further information on change blindness, inattention blindness and expectation bias.

Aviation Short Investigations Bulletin - Issue 56

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

__________

1. Pilot Flying (PF) and Pilot Monitoring (PM) are procedurally assigned roles with specifically assigned duties at specific stages of a flight. The PF does most of the flying, except in defined circumstances; such as planning for descent, approach and landing. The PM carries out support duties and monitors the PF’s actions and the aircraft’s flight path.
2. Last light: the time when the centre of the sun is at an angle of 6° below the horizon following sunset. At this time, large objects are not definable but may be seen and the brightest stars are visible under clear atmospheric conditions. Last light can also be referred to as the end of evening civil twilight.

What happened

On 25 August 2016, a Robinson R44 helicopter, registered VH-EYD (EYD), departed from Bankstown Airport on a training flight to Camden Airport, New South Wales. On board were a student pilot and a flight instructor. After completing exercises in the Camden area, the helicopter returned towards Bankstown.

According to air traffic control (ATC) audio data, at about 1607 Eastern Standard Time (EST), the instructor of EYD contacted the Bankstown aerodrome controller (ADC), advising that they were at inbound reporting point 2RN at 1,000 ft (Figure 1). The ADC instructed EYD to track via, and report at, ‘Choppers South’ reporting point at 500 ft. EYD then tracked via Choppers South at 500 ft, but the instructor omitted to advise ADC when they were overhead that point.

Figure 1: Extract of Sydney Visual Terminal Chart

Source: Airservices Australia – annotated by ATSB

At about 1610, the solo student pilot of a Cessna 152 aircraft, registered VH-MRC (MRC), who was conducting circuit training at Bankstown Airport, contacted the ADC and stated that MRC was on the downwind circuit leg, and requested clearance to depart the control zone on the upwind circuit leg. The ADC instructed the pilot of MRC to ‘go around from base, maintain 1,000 ft and depart on upwind’.

The pilot of MRC asked the ADC to repeat the instruction and then read back ‘MRC going around from base and depart at 1,000 ft’. The pilot of MRC then continued their approach, descending on the base leg and final approach to about 300 ft above the runway before commencing a go-around. At about 1613, passing about 500 ft on climb, the pilot of MRC advised the ADC that they were going around and departing at 1,000 ft upwind.

The ADC reported that they sighted MRC about mid-way along the runway, lower than the assigned altitude of 1,000 ft, and also sighted EYD about 200 m away at about the same altitude (Figure 2). The ADC immediately issued a safety alert^[1] to the pilot of MRC advising of a helicopter (EYD) to their left crossing midfield at 500 ft. The ADC then issued a safety alert to EYD advising of the Cessna (MRC) in the go-around.

The instructor of EYD had already sighted MRC and commenced a right turn to increase separation. On receiving the safety alert, the pilot of EYD continued the right turn to pass behind MRC. EYD landed at the western helipad without further incident. MRC departed to the training area, before returning to land at Bankstown Airport, also without further incident.

Figure 2: Indicative aircraft tracks

Source: Airservices Australia – annotated by ATSB

Aerodrome control and radio frequencies

There were two Tower frequencies and two ADC positions at Bankstown, with ADC1 having responsibility for arrivals and departures on runways 29 right/11 left and 29/11 centre; ADC2 was responsible for the training circuit with runway 29 left/11 right.

The two Tower frequencies at Bankstown were combined at the time of the incident, and one controller occupied the ADC position. When combined, pilots of aircraft operating on either the circuit Tower frequency or the arrivals and departures Tower frequency would have been able to hear transmissions on the other frequency. Although the pilots of MRC and EYD had different radio frequencies selected, they were combined such that the transmissions made on both frequencies could be heard on either frequency.

Pilot comments

Pilot of MRC

The pilot of MRC was a student with 41 hours of aeronautical experience, six of which were solo. They provided the following comments:

• They had not departed from the circuit runway to the training area previously and were not sure how to do so or what to expect from ATC.
• Their understanding of a go-around was to descend as if on a normal approach to the runway, discontinue the approach on final at about 300 ft, apply full power and commence a climb, and diverge to the left of the runway.
• They misunderstood the ADC’s instruction, but were unsure why the controller had not noticed the aircraft descending on base and final before it commenced the go-around.
• They were not aware of the Choppers South arrival procedure until after the incident.
• If the instruction had been sequenced differently, with the direction to maintain 1,000 ft first, it would have made the ADC’s expectations clearer.

Controller comments

The ADC commented that if the pilot of MRC had maintained 1,000 ft there would not have been a separation issue. Having issued the instruction to maintain 1,000 ft, the ADC turned their focus to monitoring other aircraft and communicating with the pilots of other aircraft in the control zone.

The controllers have a liaison role with local flying schools, which involves visiting them and talking to the students, and they also invite students to the tower during quiet periods. This liaison fosters a safer working relationship between pilots and air traffic control.

Go-around

Aeronautical Information Package (AIP) En Route (ENR) 1.1 – 16.4 stated:

At Class D aerodromes with parallel runways where contra-rotating circuit operations are in progress, if ATC instructs, or a pilot initiates a go around, the pilot must:

commence climb to circuit altitude

position the aircraft on the active side and parallel to the nominated duty runway, while maintaining separation from other aircraft and

follow ATC instructions or re-enter the circuit from upwind.

The Manual of Air Traffic Services defined a go-around as a ‘procedure in which the pilot discontinues the approach immediately and rejoins for another circuit, or proceeds as directed by ATC’.

The ADC commented that when they issued the instruction to go around, they expected the pilot of MRC to terminate their approach and maintain 1,000 ft while continuing to fly the circuit geographically.

En Route Supplement Australia

The ERSA entry for Bankstown included the following under the heading Class D:

‘CAUTION: HELICOPTERS OVERFLY RUNWAYS MIDFIELD AT 500FT.’

Operator comments

The operator of MRC provided the following comments:

• Helicopter pilots inbound via Choppers South should be aware that crossing a training circuit runway is inherently risky as a go around can occur at any time and is obviously more likely to occur with low time student pilots who are more likely to not have their approach to land stabilised.
• It is also very likely that during their initial solo circuit training students will be more likely to be focussing on the preceding traffic they are following and will be less likely to see crossing helicopter traffic in their peripheral vision.
• Bankstown is a very busy training environment, which can have sudden increases in traffic volume. ATC needs to be aware of this as it is very difficult for student pilots to monitor traffic and radio calls and make broadcasts when conjoined frequencies are in operation, and there is a heavy traffic load.
• It is, and it always will be, company policy to safely fly the aeroplane first, navigate to the southern side of the runway and then communicate their intentions/actions.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Operator of VH-MRC

As a result of this occurrence, the operator of MRC has advised the ATSB that they are taking the following safety actions:

Amended operations manual

The operator of MRC is proposing to amend their operations manual to read:

Unlicensed solo pilots are not permitted to request circuits on arrival or when inbound to Bankstown. Unlicensed solo pilots may only depart the training circuit after they have demonstrated proficiency in the procedure to an instructor and a note has been made in the training record to that effect

Safety message

The Civil Aviation Safety Authority booklet, Class D airspace, advises pilots that when operating in Class D airspace, they must sight and maintain separation from other aircraft. Pilots and ATC have a dual responsibility to maintain situational awareness of other traffic.

Aviation Short Investigations Bulletin - Issue 54

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

__________

1. ATC will issue a Safety Alert to aircraft, in all classes of airspace, when they become aware that an aircraft is in a situation that is considered to place it in unsafe proximity to: terrain; obstruction; active restricted or prohibited area; or other aircraft.

What happened

On 31 May 2016 at 1018 Eastern Standard Time (EST), Virgin Australia Airlines flight VA1615, an Embraer ERJ 190 aircraft, registered VH-ZPJ (ZPJ), departed Melbourne Airport on a scheduled passenger service to Mildura Airport, Victoria. On board the aircraft were 2 flight crew, three cabin crew and 81 passengers. The aircraft captain was the pilot flying (PF) and the first officer was the pilot monitoring (PM).^[1]

About 40 NM from Mildura and just prior to ZPJ leaving controlled airspace, air traffic control (ATC) passed the flight crew traffic information about two aircraft operating above 10,000 ft to the west of Mildura Airport. In addition, there was also a public transport flight inbound to Mildura from Broken Hill and a light twin-engine aircraft inbound to Mildura on a converging track to ZPJ. The PM on board ZPJ contacted the light twin-engine aircraft and confirmed they would arrive at Mildura after ZPJ. The estimated arrival time for the public transport flight at Mildura was also later than the estimate for ZPJ, and consequently the flight crew on board ZPJ did not consider any of the traffic passed to them by ATC would conflict with their own arrival.

The aircraft operating to the west of Mildura were a GippsAero GA10 aircraft, registered VH-XGY (XGY), conducting spin testing supported by a Gippsland Aeronautics GA-8 ‘chase plane’, registered VH-XGA (XGA), from the same company.

ZPJ joined the Mildura Airport circuit on the crosswind leg for a left visual circuit to land on runway 09.

On the base leg of the circuit, the flight crew on board ZPJ heard their traffic collision alert system (TCAS) announce a traffic advisory (TA) aural alert (see TCAS limitations on approach). They glanced at their TCAS display to check the relative position of the traffic, which indicated it was to their right (position 1 in Figure 1). The flight crew looked out the right window of the flight deck and identified the traffic to their right and high against the skyline. The traffic appeared to them to be stationary in the windscreen relative to their own aircraft and with a high closure rate (from TCAS data the aircraft were 1.25 NM apart at the time of the TA alert).^[2]

The PM on board ZPJ contacted the other traffic on the radio and requested their intentions. The other traffic was XGA, which was leading XGY back to Mildura Airport for a straight-in approach to runway 09. When the pilot of XGA responded that they were tracking for a straight-in approach to runway 09, the PM assessed they were on a collision course on their present track. They also recognised that there would be a potential risk of collision if both aircraft performed a go-around to the south of the main runway. Therefore, the PM responded to the pilot of XGA to immediately turn and remain south of the airport. The pilot of XGA identified ZPJ ahead of them on approach to runway 09 and responded that they would discontinue their approach and manoeuvre to the south of the airport.^[3]

The PF on board ZPJ decided to discontinue their approach to land on runway 09, as they were too late for their turn onto final and therefore not in a stabilised condition.^[4] However, the PM indicated to the PF that they could not execute a go‑around manoeuvre because there was another aircraft joining the circuit on crosswind (the light twin-engine aircraft). The PF decided that continuing the approach to land was not an option and therefore executed the go‑around to the south of runway 09, maintained separation from the other traffic on crosswind and then landed from the subsequent circuit. During the go-around manoeuvre, the aircraft’s TCAS detected XGA pass about 200 ft above and 0.125 NM behind ZPJ (position 7 & 8 in Figure 1).

Figure 1: Traffic conflict between ERJ 190 (VH-ZPJ) and GA-8 (VH-XGA)

Source: Google earth, annotated by ATSB based on Virgin Australia Airlines TCAS data (numbers indicate the relative positions of the conflict aircraft at the same time)

Airspace

Class E airspace

A Class E controlled airspace corridor extends from Melbourne to overhead Mildura Airport with a lower limit of FL 125.^[5] In Class E airspace, instrument flight rules (IFR) traffic, such as ZPJ, require a clearance. Visual flight rules (VFR) traffic, such as XGA and XGY, do not require a clearance, but should monitor the Class E airspace air traffic service frequency. In Class E airspace, IFR flights are separated from other IFR flights and receive traffic information on VFR flights as far as practicable. ZPJ left Class E airspace on descent to Mildura about 37 NM from Mildura Airport, at which point ZPJ entered Class G airspace for the remainder of the flight.

Class G airspace

Class G airspace is non-controlled airspace. IFR and VFR traffic are permitted without a clearance and there is no separation service provided by ATC. Mildura Airport is a non-controlled aerodrome with a discrete common traffic advisory frequency (CTAF), which is a different frequency from the surrounding Class G airspace area frequency. About 10 NM to the north-west of Mildura Airport is Wentworth Aerodrome. Wentworth uses the same CTAF as Mildura.

Radio broadcasts at non-controlled aerodromes

The following Table 1 indicates the non-controlled aerodrome radio broadcast requirements for inbound aircraft in accordance with the aeronautical information publication (AIP).

Table 1: Summary of broadcasts required for inbound aircraft at non-controlled aerodromes

Incident flight radio broadcasts

During the spin testing of XGY, XGY was classified as ‘lead’ aircraft and XGA as ‘in-trail’. The pilot of XGA set one of their two radio frequencies to their company frequency, for communication with XGY, and the other to area frequency, for communication with other traffic if required. While operating on the area frequency, the pilot of XGA heard a broadcast from ZPJ that they were inbound to Mildura from Melbourne, and a broadcast from another public transport aircraft inbound to Mildura from Broken Hill. On completion of the spin testing, XGA assumed the lead from XGY at about 10,000 ft and 11–12 NM from Mildura Airport. Shortly after the lead change, the pilot of XGA changed from area frequency to the Mildura CTAF.

The pilot of XGA made a 10 NM broadcast on CTAF, which included their position, altitude and intentions for a 5 NM straight in approach for final approach to runway 09. They received an immediate response from the public transport aircraft tracking from Broken Hill, who provided an estimated time of arrival for their 5 NM final approach position for runway 09. The pilot of XGA responded with a revised estimate for their arrival on the ground at Mildura Airport, which was the same time as the other aircraft’s estimate for their 5 NM final position. At the end of this exchange, XGA, with XGY in-trail, was about 7 NM from Mildura Airport tracking to the north-east to intercept a 5 NM final position, at 140–150 kt airspeed, descending at about 2,000 ft per minute. The pilot of XGA heard no radio broadcasts from ZPJ on CTAF and assumed they had already landed.

XGA made a right turn onto final approach for runway 09 at about 3,200 ft, 4.5 NM^[6] from the runway threshold. Shortly after the turn, the pilot of XGA heard a broadcast requesting their intentions from ZPJ. Following the initial exchange of broadcasts with ZPJ, the pilot of XGA visually identified ZPJ about 2 NM ahead on approach to runway 09. They recognised that ZPJ had right-of-way and made a broadcast that they were ‘breaking off’ their approach to runway 09 and turning south.

The PM duties on board ZPJ included managing the radio communications with other traffic. During the approach to join the circuit, and subsequently while flying the circuit, the captain was preoccupied with PF duties and did not comprehend all the radio broadcasts. However, the PM made several CTAF broadcasts, which started at 42 NM from Mildura at 01:06:35. The last broadcast before entering the Mildura circuit was just prior to ZPJ crossing overhead runway 09 to join crosswind at 01:15:27. The next CTAF broadcast made by ZPJ was at 01:18:16, after they turned base. The flight crew received a TA at 01:18:31 and subsequently made a broadcast to challenge the intentions of XGA at 01:18:43.

Incident aircraft geometry

The following Table 2 indicates the positions of ZPJ and the conflict aircraft XGA. Figure 2 depicts the geometry of traffic in the vicinity with numbering in accordance with Table 2. The positions of the aircraft are based upon TCAS data from ZPJ.

Table 2: Aircraft geometry

Figure 2: Aircraft geometry from Table 2

Source: Google earth, annotated by ATSB based on Virgin Australia Airlines TCAS data.

TCAS limitations on approach

The traffic alert and collision avoidance system (TCAS) II, will display traffic to the flight crew as: other traffic, proximate traffic, traffic advisory,^[7] or resolution advisory.^[8] However, only traffic advisories and resolution advisories trigger an aural alert to the flight crew.

The collision avoidance system logic is based on the concepts of sensitivity level (SL), threshold time (tau) for issuing a traffic alert or resolution advisory, and protected volume of airspace around the TCAS equipped aircraft. The higher the SL, the greater the volume of protected airspace. As SL reduces, the volume of protected airspace reduces and TCAS functions may become inhibited.

Tau is an approximation of the time, in seconds, to the closest point of approach of another aircraft. This forms the basis for the alerting functions and therefore the volume of protected airspace. Therefore, a reduction in the TCAS SL reduces the volume of protected airspace by reducing the value of tau.

Below 1,000 +/-100 ft above ground level, the TCAS SL reduces from SL3 to SL2. For the ERJ 190 this equates to 900 ft when on descent and 1,100 ft when on climb. From SL3 to SL2 the tau reduces from 25 seconds to 20 seconds and resolution advisories are inhibited. Below 500 +/-100 ft above ground level, TCAS aural alerts are inhibited. For the ERJ 190 this equates to 400 ft when on descent and 600 ft when on climb. Close to the ground, the windshear and ground proximity warning system alerts have a higher alert priority.

The PM on board ZPJ commented that during the visual circuit they changed the focus of their scan from inside the cockpit to outside the cockpit. They suspect that XGA was probably displayed as other traffic on their TCAS before they received the TA alert. However, there are no company procedures specific to the use of TCAS at non-controlled aerodromes. Company procedures emphasise the importance of flight crew maintaining a ‘constant lookout when operating within a CTAF’, and use positive altitude separation or alternatively coordinate a track deviation with conflict aircraft.^[9]

Limitations with visual sighting

Three limitations to sighting other traffic, of interest to this incident, are:

• alerted search versus unalerted search
• lack of relative motion on collision course
• effects of complex backgrounds

Alerted search versus unalerted search

Traffic alerts may come from radio calls or TCAS at a non-controlled aerodrome. Knowing where to look has been shown to improve visual detection of other traffic. The PF on board ZPJ was alerted to the potential conflict by TCAS, and then visually identified XGA. The pilot of XGA was alerted to the potential conflict following ZPJ’s radio broadcast on the base circuit leg, and then visually identified ZPJ.

Lack of relative motion on collision course

The PF on board ZPJ commented that when they visually sighted XGA, the aircraft appeared to be stationary in the windscreen, which indicated a potential collision course. In this case ZPJ would also appear stationary to the pilot of XGA. Lack of relative motion against a background reduces the probability of visual detection.

Effects of complex backgrounds

When the PF on board ZPJ visually identified XGA, XGA was above the horizon (higher altitude relative to ZPJ) and against a background of sky. For the pilot of XGA, ZPJ was lower and against a background of terrain. The pilot of XGA was therefore required to detect the contrast between the aircraft and terrain to detect ZPJ. A terrain background may create a complex background and reduce the probability of visual detection.

Safety analysis

The AIP directs pilots to the minimum required radio broadcasts when operating at non-controlled aerodromes and the pilots of ZPJ and XGA complied with these requirements. However, it is likely that the pilot of XGA was not on the Mildura CTAF when the PM on board ZPJ made a broadcast that they were joining the Mildura circuit. When the pilot of XGA switched to the Mildura CTAF they were initially occupied with communicating with another public transport aircraft inbound from the north and considered this aircraft to be their only potential conflict. It could not be determined why the flight crew on board ZPJ did not comprehend the presence of a potential conflict from this radio traffic. However, the flight crew of ZPJ had previously dismissed these two aircraft (XGA and XGY) as a potential conflict for their arrival.

After ZPJ turned onto the base leg for runway 09, the PM made a base radio broadcast. It could not be determined why the pilot of XGA did not comprehend the presence of a potential conflict from this broadcast. However, the investigation could not rule out the possibility that other aircraft operating at Mildura or Wentworth made broadcasts which interfered with one or several of the broadcasts made by ZPJ or XGA.

Shortly after the base leg radio broadcast from the PM in ZPJ, the flight crew were alerted to the presence of XGA by a TCAS TA aural alert. At this time ZPJ was below 900 ft and therefore TCAS resolution advisory was inhibited. However, the TCAS visual display of the relative position of XGA cued their visual search and facilitated a quick identification. XGA appeared to the flight crew on board ZPJ as stationary against a background of sky. Therefore, to the pilot of XGA, ZPJ was probably against a more complex background with no relative motion, contributing to the difficulty for the pilot of XGA to detect ZPJ before they were alerted by the radio call by ZPJ.

The radio broadcast from the PM on board ZPJ directed to the ‘traffic inbound to Mildura from the west’ alerted the pilot of XGA to the presence of other traffic and cued them to search for the conflict. The PM on board ZPJ then directed the pilot of XGA to ‘turn immediately away to the south’ to avoid a potential collision either during their turn onto final approach or in the event that both aircraft attempted a simultaneous go-around manoeuvre on the south side of runway 09.

After receiving an acknowledgement from the pilot of XGA, the flight crew on board ZPJ turned their attention to the execution of their go-around manoeuvre as their turn onto the final leg of the circuit was late due to their preoccupation with monitoring XGA. However, during their turn to join the upwind circuit leg for runway 09 on the south side of the runway, XGA continued to converge to a closest point of 0.125 NM behind and about 200 ft above ZPJ before making an abrupt turn to the south. This was the result of the intention of the pilot flying XGA to join the upwind leg of the circuit to the south of runway 09, before they realised that ZPJ was also conducting a go-around from their approach.

Findings

These findings should not be read as apportioning blame or liability to any particular organisation or individual.

• The pilot of XGA was probably not monitoring Mildura CTAF when the PM on board ZPJ broadcast joining the Mildura circuit.
• The flight crew of ZPJ did not detect the broadcast from XGA that they were intending to join a straight in approach to runway 09.
• After a separation strategy was agreed, XGA continued to close on ZPJ to a closest point of approach of 0.125 NM behind and 200 ft above ZPJ when ZPJ started their go-around.
• Both aircraft made the required broadcasts on the CTAF.
• The flight crew on board ZPJ were cued to the conflict by their TCAS traffic advisory alert.
• The pilot on board XGA was cued to the conflict by the radio broadcast from ZPJ.

Safety message

Despite compliance with the radio broadcast requirements, a traffic conflict occurred in an environment with limited manoeuvring options for a high-capacity public transport aircraft. This incident highlights the importance of an alerted search to the successful identification of potential conflict traffic. Further information is available from ATSB Research report: Limitations of the See-and-Avoid Principle.

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 relates to safety around non-controlled aerodromes.

Aviation Short Investigations Bulletin - Issue 56

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 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 Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: 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.

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1. Pilot Flying (PF) and Pilot Monitoring (PM): procedurally assigned roles with specifically assigned duties at specific stages of a flight. The PF does most of the flying, except in defined circumstances; such as planning for descent, approach and landing. The PM carries out support duties and monitors the PF’s actions and the aircraft’s flight path.
2. Traffic that is closing, but appears stationary in the windscreen, is indicative of a collision course. In this case, the ERJ 190 will also appear stationary in the windscreen of XGA.
3. Traffic in the circuit have ‘right-of-way’ over traffic tracking for a straight-in approach.
4. Stabilised approach criteria is used for identifying the need for a go-around or missed approach. For the ERJ 190 this included being established on runway centreline with wings level by 500 ft above ground level.
5. Flight level: at altitudes above 10,000 ft in Australia, an aircraft’s height above mean sea level is referred to as a flight level (FL). FL 125 equates to 12,500 ft.
6. This position is based upon TCAS data from VH-ZPJ and is indicative only.
7. An indication given by TCAS to a flight crew when an aircraft has entered, or is projected to enter, the protected volume of airspace around their own aircraft.
8. An indication given by TCAS II to a flight crew that a vertical manoeuvre should, or in some cases should not, be performed to attain or maintain safe separation from another aircraft.
9. Aircraft not equipped with transponders may be operated in non-controlled airspace, in which case they will not be detected by TCAS.