On 2 July 2016, at about 1420 Eastern Standard Time (EST), a de Havilland DH-82A aircraft, registered VH-ARU, departed Shute Harbour aircraft landing area (ALA), Queensland, for an aerobatic joy flight. On board were a pilot and one passenger.
When the aircraft reached about 4,500 ft over water, the pilot advised air traffic control (ATC) that they were commencing aerobatic operations. The pilot reported that they then raised the aircraft nose and reduced the throttle to idle. The aircraft then pitched nose-down and the pilot initiated a rotation to the left. After about one and a half rotations, the pilot levelled the aircraft wings and stopped the rotation. As the airspeed was then about 110 kt, which was the entry speed for the next manoeuvre (a loop), the pilot raised the aircraft nose and applied full power as the nose passed the horizon.
The aircraft was then passing about 3,500 to 4,000 ft on climb, when the pilot and passenger heard a bang. The pilot saw a small object fly past to their left in close proximity, and the passenger saw that the on-board camera had been knocked.
The pilot discontinued the manoeuvre and stabilised the aircraft in a glide attitude. As the aircraft continued to descend, the pilot elected to return to Shute Harbour ALA. The pilot reported that the aircraft was not vibrating and the tachometer was indicating maximum RPM. The pilot also assessed that the engine was not producing any thrust, regardless of the throttle position. The pilot advised ATC that they had completed operations and were returning to Shute Harbour. At no time did the pilot inform ATC that there was an emergency.
As the aircraft passed the highest terrain en route to Shute Harbour ALA, the pilot assessed that they were not going to be able to reach the ALA (Figure 1). The pilot then turned the aircraft to land on the beach at Funnel Bay, but sighted boats moored on the beach. The pilot therefore aimed to land the aircraft at Funnel Bay on the mudflats. The pilot conducted a forced landing onto the mud and the aircraft continued onto some rocks. After landing, as the pilot inspected the aircraft, they noticed that the propeller was missing.
Figure 1: Shute Harbour ALA and Funnel Bay
Source: Google earth – annotated by ATSB
The pilot was uninjured, and the passenger sustained minor injuries. The aircraft sustained substantial damage (Figure 2).
Figure 2: Accident site showing damage to VH-ARU
Source: Aircraft owner – modified by ATSB
Pilot comments
The pilot had completed a daily inspection of the aircraft earlier in the day and had subsequently flown it for about 6 minutes to assess the weather conditions. The incident flight was the first commercial flight of the day. During the pre-flight inspection, the pilot reported having made a visual check of the propeller for defects, gravel rash and any chips, but had not detected anything abnormal.
The pilot had asked the passenger their weight prior to the flight, and although they did not complete a weight and balance calculation, assessed that the aircraft was within its weight and balance limitations for aerobatic flight.
At the time of the incident, they were operating about 4 to 5 NM from the ALA, and over water. The pilot thought that the aircraft probably struck a bird resulting in the propeller failing.
When they realised that the aircraft was unable to reach the runway at Shute Harbour, the pilot had a secondary plan to land on the beach at Funnel Bay. They commented that their training helped to deal with the situation by being aware of their surroundings and having a series of plans in case of emergency.
Engineering report
The aircraft maintenance engineer assessed the aircraft after the incident and sent the remnants of the (timber) propeller that had remained attached to the aircraft to the ATSB. The engineer also spoke to the manufacturer of the propeller and was able to trace its history. The manufacturer suggested the propeller failure was indicative of a propeller overspeed, although they did not inspect the propeller remnants. The propeller was not retrieved as it failed when the aircraft was over water.
ATSB analysis
Video footage
The ATSB analysed the data card from the on-board camera. The camera was facing rearwards and no evidence of a birdstrike was visible on the footage when viewed frame-by-frame. Analysis of the sound component of the recording was conducted to determine the engine frequency at the time of the propeller failure, but the results were inconclusive due to background noise including a radio transmission.
From the video footage, it was evident that the aircraft entered a spiral manoeuvre that involved substantial rudder and aileron input such that the aircraft was in balance (not skidding or slipping sideways). The wings were then levelled and the aircraft pulled out of the dive. The propeller failed just as the aircraft nose passed back up through the horizon at the start of the next manoeuvre and power was applied. The propeller was under substantial load at this stage.
Propeller remnants
The ATSB examined two fragments of the propeller that were identified as parts of the hub section. An area of interest, depicted in Figure 3, showed evidence of bending consistent with the blade breaking away from the hub while under load. No bird remains were found on the fragments. The factors contributing to the propeller failure could not be determined from the timber fragments.
Figure 3: Propeller remnants
Source: ATSB analysis
ATSB comment
One of the findings of ATSB investigation AO-2013-226, In-flight break-up involving de Havilland DH82A Tiger Moth, VH-TSG, 300 m E of South Stradbroke Island, Queensland, 16 December 2013, was that ‘publicly-available video recordings showed that some Australian commercial Tiger Moth operators conducted aerobatic flick (otherwise known as ‘snap’) rolls and tailslide manoeuvres, which were prohibited by the Type Design Organisation’. However, the on-board video recording showed that the types of aerobatic manoeuvres conducted during the accident flight were all permitted for the aircraft type.
The ATSB cautions commercial vintage aircraft operators about the risks associated with aircraft age and the importance of understanding the originally-intended use of the design before commencing their operations.
Safety message
This incident highlights the value of always having a consideration of landing areas available in case a forced landing is required. Alerting air traffic control as emergencies arise enables them to provide the necessary and appropriate assistance.
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
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.
On 4 July 2016, at about 0940 Eastern Standard Time (EST), a Piper PA31‑325 aircraft, registered VH-ETW (ETW), departed from Birdsville Airport, Queensland for a scenic flight to Lake Eyre, South Australia and refuelling at Marree. The pilot and four passengers were on board the charter flight.
On the return flight to Birdsville, at about 1410, the pilot broadcast on the common traffic advisory frequency (CTAF) indicating that they were about 30 NM south-west of Birdsville for a landing on runway 32. Later a pilot of a SAAB 340 aircraft also broadcast on the CTAF that they were about 15 NM east of Birdsville for a straight in approach, landing on runway 32, with a similar arrival time to ETW.
The pilot of ETW overflew the airport at about 2,500 ft on the upwind end of runway 32 to reduce the possibility of a conflict with the arriving SAAB (Figure 1). ETW joined for a wide downwind leg of the circuit and the pilot lowered the landing gear. The pilot observed that the SAAB that had now landed had not vacated the runway, so the pilot retracted the landing gear and extended the downwind leg to allow further time for the SAAB to vacate the runway.
Figure 1: Birdsville airport showing the location of runway 32, the parking apron and where the birds (hawks) were generally located off the end of runway 32 (orange circle).
Source: Google earth, modified by the ATSB
The pilot conducted the downwind checklist that included checking that the landing gear was down and locked, however, as the landing gear was in the up position, this part of the checklist was not conducted. When the aircraft was towards the end of the downwind leg, the pilot selected the landing gear handle down. The pilot noticed that the landing gear selector moved out more easily than normal, but the pilot identified that three landing gear down green lights were illuminated, indicating that the landing gear was down and locked.
While the pilot was scanning out the window, they noticed a flicker of the instrument lights. When they looked back inside the cockpit, they observed that the GPS had gone back into initialising mode, which indicated that it may have lost power. During the turn onto the base leg of the circuit, the pilot gave a broadcast on the CTAF and conducted the base leg checklist items (they did not include checking the landing gear). The pilot noticed that the SAAB had not vacated the runway, but was getting close to exiting onto the apron. As the aircraft completed the turn onto the base leg, the pilot felt something against their right knee. The pilot reached down and found that it was the landing gear selector handle, which had become partially detached from the selector lever (Figure 2). The pilot took hold of the handle to ensure it was not lost and confirmed that there were three green landing gear down lights illuminated.
The pilot inserted the handle back into the landing gear selector lever and retracted and extended the landing gear to ensure that everything was operating correctly. The pilot removed the handle and kept hold of it and then gave a final leg broadcast, turned onto the final leg and conducted the finals checklist items. This checklist included a landing gear check, but the pilot could not remember clearly if there were three green lights.
At about 200 ft on final approach, the pilot observed a significant number of birds (hawks) (see orange circle in Figure 1). Due to a 15kt crosswind, as the pilot flared the aircraft for landing, the aircraft moved to the right side of the runway and the pilot then noticed that the aircraft had a slightly higher nose attitude than normal. As the attitude kept increasing, the pilot slowly advanced the throttles, then the rear footstep touched the runway and made a scraping noise. The pilot decided not to close the throttles as the aircraft was not on the runway centreline and they continued to advance the throttles. As the speed increased, the aircraft attitude adjusted and the propellers struck the runway. The aircraft speed had increased to take off speed and the pilot assessed that the safest option was to continue with a take-off. The pilot did not notice any abnormalities with the engines.
The pilot conducted a circuit, selected and held the landing gear handle in the down position and the aircraft landed without further incident. The pilot and passengers were uninjured and the aircraft had minor damage to the propellers (Figure 3).
Figure 3: Damage to ETW propellers
Source: Pilot, modified by the ATSB
Pilot comment
The pilot reported that when the landing gear was selected down when on the final approach, the landing gear selector was easier than usual to pull out and move past the neutral stop to the gear down position.
The pilot reported hearing a continuous horn sounding while in the landing flare just as the throttle was advanced and believed that it was the stall warning horn. The pilot believed that the landing gear horn would not have sounded as the throttles were not decreased past the location of the limit switches, which is where the throttles are almost closed (see Landing gear system below).
The pilot indicated that after parking the aircraft on the apron, when the avionic switch was moved to the off position, the avionics remained on and it was not until the switch had been cycled several times between the on and off position did the avionics turn off.
The pilot returned to the aircraft a few days later and noted that when the electrical master switch was turned on there were no green landing gear indicator lights despite the wheels being down, indicating the aircraft still had an avionics defect.
The pilot indicated that a maintenance release inspection (the periodic (100 hourly or 12-month) maintenance inspection) had been completed on 13 May 2016 and about 15 hours prior to the occurrence. The pilot had been the only pilot to fly the aircraft since the 100 hourly inspection and had flown a flight earlier that day and not noticed any issues with the aircraft.
Landing gear system
The landing gear handle is attached to the landing gear lever by a sleeve that fits over the end of the lever and is held in place by a pin, which is retained by a split pin. In this incident, the pin and split pin had fallen out of the landing gear handle and lever. In addition to connecting the handle to the lever, the pin also interacts with a gear handle stop (Figure 4). The landing gear handle is designed so the handle is spring-loaded to a forward position (towards the instrument panel). The pin on the inboard side of the handle rests against the gear handle stop for the neutral up and neutral down position. This ensures that the landing gear handle cannot unintentionally be moved beyond the neutral stop.
To select the landing gear down, the gear handle is pulled away from the instrument panel, down and over the gear handle stop to the full down position. When the landing gear is fully extended and locked, the landing gear handle will then return automatically to the down-neutral position where it is held by the pin against the gear handle stop.
Located on the instrument panel, above and to the right of the landing gear handle are one red and three green indicator lights (Figure 4). The red light will illuminate when the gear is not locked and the gear handle is either in the up or down position. When each of the individual gear is down and locked the respective green light will illuminate. There is no indication light when the gear is up and locked. When power from either engine is reduced below 10 to 12 inches of manifold pressure, a horn in the cockpit should sound if the gear is not down and locked.
Figure 4: Landing gear selector handle showing the gear handle, lever assembly, gear handle pin and the up and down neutral positions. In addition, the red unlocked light and the green down locked lights.
Source: Canada Transport Safety Board, modified by the ATSB
Operator report
The operator conducted an investigation into the occurrence and determined that the aircraft’s avionics were found to start up with the battery master switch, even though the avionics master switch was selected off. In addition, although the landing gear was down and locked, there were no green lights to indicate that this was the case. There was no indication of what the mechanical fault was in this system.
An inspection of the aircraft determined that when the gear handle was moved to the landing gear down position, it would normally return to the down neutral position. However, on the occurrence flight, the gear handle pin fell out. Without the gear handle pin to stop the landing gear lever at the gear handle stop, the lever continued to the gear up position (past the down neutral position to the up position) The landing gear retracted without the pilot being aware. However, the gear down and locked lights should have still illuminated prior to landing if the landing gear was down and locked.
Distractions for the pilot included the landing gear handle becoming detached, an issue with the avionics on downwind, numerous birds (kite hawks) that were flying around on final and the 15 kt crosswind.
Safety analysis
When the pilot had discovered that the landing gear selector handle had become detached, they used the detached handle to move the lever to retract and extend the landing gear to determine that there were no issues with the landing gear prior to the landing. The pilot then removed the handle to ensure that it did not fall and become inaccessible in flight, just in case the landing gear needed to be retracted and extended again. They believed that there were three green landing gear down indicator lights but was unaware that with the stop pin missing, the landing gear would self-retract after the landing gear handle was released. As a result, the pilot was not aware that the landing gear had retracted prior to landing.
There were a number of interruptions and distractions during the approach and landing phase of the flight. These included waiting for another aircraft to vacate the runway and subsequent alteration of the circuit to accommodate separation, issues with the GPS, the landing gear handle becoming free, large birds under the final approach and the crosswind during the landing. The combination of these interruptions, distractions and abnormal conditions likely contributed to the pilot flaring the aircraft for landing without realising the landing gear was in the retracted position.
Findings
These findings should not be read as apportioning blame or liability to any particular organisation or individual.
The landing gear selector handle became detached and the landing gear retracting without the pilot’s knowledge.
Numerous distractions existed during the approach and landing that may have contributed to distract the pilot resulting in the aircraft landing with the landing gear in the retracted position.
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 operator
As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:
The pilot has undertaken comprehensive successful flight checks.
Aircraft defect rectification to ensure the aircraft is serviceable before further flight.
The aircraft operations manual will be amended to include actions to be taken when experiencing any abnormality with the aircraft’s landing gear. This will refer to the emergency procedures checklist and the aircraft flight manual. The procedure will require the pilot to:
abort the landing
climb to 1,500 ft
redo the pre-landing landing checklist to confirm green lights are on/or use the emergency landing gear hand pump to lower the landing gear.
conduct a visual inspection of landing gear to ensure it is down and locked.
All pilots will be informed of the incident via email or a safety alert to inform them:
of the importance of the gear control handle locking mechanism
to inspect the gear control handle on a regular basis for faults or damage
to look at additional options for confirming that the landing gear is down with the use of active control towers or having contact details of ground crew readily available to inspect the landing gear during a fly over.
Safety message
In the flying environment, interruptions and distractions can be subtle and brief and can interrupt the normal flow in the cockpit resulting in a preoccupation and distraction with one task to the detriment of another task.
discuss that interruptions/ distractions may be subtle or brief where even a minor equipment malfunction can turn a routine flight into a challenging event. The primary effects of interruptions/distractions is to break the flow pattern of ongoing cockpit activities such as normal checklists and problem-solving activities. The briefing contains guidance that may assist in managing interruptions/ distractions.
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
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.
The ATSB has completed examination of the JRA-445-1 wing attachment fitting supplied by the Civil Aviation Safety Authority (CASA). In addition, an original Cessna wing attachment fitting (part no. 0811350-10), also supplied by CASA, was examined for comparison of the material properties and manufacturing methodology. A report detailing the examinations and findings was prepared and provided to CASA on 28 September 2016.
For further information regarding the wing fittings or airworthiness bulletin AWB 57-015, please contact CASA on 131 757 or www.casa.gov.au.
Updated: 30 June 2016
During an inspection of the wing attachment fittings of a Cessna 402C in accordance with Civil Aviation Safety Authority (CASA) airworthiness directive AD/CESSNA 400/92, a crack was identified in the inboard lower attachment fitting (Figure 1). The cracked attachment fitting (part number JRA‑445‑1) was manufactured by J&R Aerospace as a replacement for the original Cessna fitting.
Figure 1: Cessna 402C lower inboard wing main spar attachment fitting showing an approximate 100 mm (4 inch) crack (indicated by orange arrow) Source: CASA, annotated by ATSB
AD/CESSNA 400/92 specified inspection of the outboard attachment fittings, but not the inboard fittings. Compliance with the airworthiness directive was required prior to the component exceeding 5,000 hours time in service. The cracked JRA‑445‑1 fitting had accumulated 2,831 flight hours time in service.
On 17 June 2016, CASA issued airworthiness bulletin AWB 57‑015 to alert operators and maintainers of Cessna 400 series aircraft of premature cracking in a Cessna 402C wing attachment fitting manufactured by J&R Aerospace.
As part of their investigation, CASA requested the technical assistance of the Australian Transport Safety Bureau (ATSB) to conduct a metallurgical examination of the cracked fitting.To facilitate this assistance, the ATSB initiated an external investigation under the provisions of the Transport Safety Investigation Act 2003.
On 20 June 2016, a captain and first officer, employed by Cobham Aviation Services, conducted a QantasLink flight from Sydney Airport, New South Wales, to Canberra Airport, Australian Capital Territory, in a Boeing 717-200 aircraft, registered VH-YQV.
The aircraft arrived in Canberra at about 0720 Eastern Standard Time (EST), and the first officer then conducted an external inspection of the aircraft, while the captain prepared the cockpit including the take-off data for the next sector to Sydney. The captain wrote the reduced-thrust take-off data onto the take-off and landing data (TOLD) card, including a flex temperature[1] of 40 °C, which was obtained from a table in the regulated take-off (RTO) book, an engine pressure ratio (EPR)[2] of 1.39, aircraft take-off weight, flap setting 5, and the take-off reference speeds (V speeds).[3] As the runway was wet, the V speeds were obtained manually from a table in the RTO book.[4]
After completing the external inspection, the first officer returned to the cockpit and the flight crew checked the take-off data in accordance with standard procedures. The first officer assessed that based on the environmental conditions, the flex temperature should be 39°. The first officer amended the TOLD card by striking through the 40 and writing 39 next to it, and similarly amended the V speeds based on the manual V speeds provided in the table for that flex temperature.
The captain was the pilot flying[5] for the sector to Sydney, so commenced briefing for the flight. The captain read out the data from the TOLD card, including the flex temperature and EPR, and the first officer entered the flex temperature and V speeds into the take-off page of the flight management system (FMS), which then calculated an EPR.
The flight crew then completed the cockpit checklist down to the last four items, in accordance with standard procedures. At that time, a member of the cabin crew entered the cockpit to advise the flight crew that an additional 22 passengers would be boarding the flight. As the aircraft take-off weight would increase by about 2 tonnes, the first officer recalculated the take-off data. The newly derived flex temperature was 34°, and as there was not much room left on the TOLD card, the first officer overwrote the previous figure of 39 with 34. The first officer then obtained the new V speeds, which the captain crosschecked and the first officer wrote them on the TOLD card.
The aircraft communications, addressing and reporting system (ACARS) then chimed with the loadsheet coming through on the printer, and at about the same time, a cabin crewmember entered the cockpit to confirm passenger numbers and ground personnel communicated over the intercom with the flight crew about removing the wheel chocks. After entering the zero fuel weight from the loadsheet into the FMS and crosschecking the take-off weight in the FMS against the take-off weight derived on the TOLD card, the captain called for the first officer to enter the revised manually derived V speeds from the TOLD card into the FMS.
The standard procedure then was for the captain to call ‘re-flex’ before entering the amended flex temperature and flap setting from the TOLD card into the FMS. The captain was holding the TOLD card and reported stating ‘39’ as the flex temperature, having misread the ‘34’. The first officer could not recall checking the flex temperature in the FMS at that time, and thought it may have been omitted due to the interruptions.
The crew reported that the EPR calculated by the FMS based on the flex temperature and environmental conditions was 1.39. (The flight data showed that the commanded EPR at that stage was actually 1.38.) The EPR obtained from the RTO book (for flex temperature of 34°) and written on the TOLD card was 1.41. The flight crew crosschecked the FMS EPR with the TOLD card EPR, and although there was a discrepancy of 0.2, it was within the 0.3 margin allowed at that stage.[6]
After obtaining the required air traffic control clearances, the captain taxied the aircraft to the runway and commenced the take-off at about 0812. In accordance with standard procedures, the captain then moved the thrust levers forward and checked for an even spool-up of the engines to an EPR of 1.2. The captain then called ‘auto flight’ and the first officer engaged the auto-flight system. This action caused the thrust levers to move to a position where the EPR from the FMS was achieved. The captain then called ‘check thrust’ and the first officer saw that the EPR was 1.38, instead of the required EPR of 1.41 as written on the TOLD card. In accordance with standard procedures, the first officer then moved the thrust levers forward to achieve 1.41 EPR.
The flight crew thought that the aircraft was then correctly configured for the take-off, with the correct EPR, thrust and flap settings and V speeds, and the captain continued the flight. However, after about 4 seconds at 1.41, the EPR returned to 1.38 for the take-off as the thrust lever position returned to that set by the auto-flight system based on the EPR value in the FMS.
During the initial climb, the first officer identified that the flex temperature set in the FMS was 39 instead of 34. As the short sector to Sydney was busy, the crew waited until the aircraft had arrived in Sydney before discussing the incident. Both members of the flight crew assessed that tiredness due to the early start may have contributed to the flex temperature error, but that they were fit to continue to operate for the remainder of the day’s duty.
Flight data
The aircraft operator provided the ATSB with a copy of the quick access recorder (QAR) data for the incident flight. As depicted in Figure 1, the data showed the thrust lever angle set at about 25° and the EPR at 1.38 early in the take-off run. After about 4 seconds at that setting, the thrust lever angle increased to about 26° as the commanded EPR, followed closely by the actual EPR, increased to 1.41. However, after about 4 seconds at 1.41 and a further 6 seconds at 1.39, the EPR reduced to 1.38 and thrust lever angle to about 25°, where they remained for the take-off.
This indicates that although the first officer manually moved the thrust levers forward, as the auto-throttle system was engaged, it then overrode the manual thrust lever position and returned the EPR to the value set in the FMS, which was the target thrust setting. At the time, the computed airspeed was 54 kt. When the airspeed reaches 80 kt in the take-off roll, the auto-throttle system mode changes from ‘take-off thrust’ to ‘take-off clamp’ mode. In clamp mode, the auto-throttle servo does not have power and the thrust levers do not move automatically. However, in take-off thrust mode (prior to 80 kt), the flight crew would have to disengage the auto-throttle system to set the thrust manually, or maintain pressure on the levers until the airspeed reached 80 kt.
Figure 1: Graph of flight data from the incident flight
Source: QAR data supplied by the aircraft operator analysed by the ATSB
Flight crew comments
During the approach into Canberra from Sydney, the cloud base was at the minima.[7] The captain commented that the workload on an instrument approach down to the minima was high, and would generally result in a reduced state of arousal after landing and shutdown in response.
The flight crew commented that a combination of distraction by cabin crew and ground personnel while re-entering data, a reduced state of arousal following high workload instrument approach, and possibly tiredness from an early start may have contributed to their omitting to enter the correct flex temperature into the FMS.
Although the captain recalled misreading 39 instead of 34, the first officer could not recall the captain calling ‘re-flex’, and commented that it was unlikely to have been called and then not completed. The first officer thought it was more likely that they entered the new V speeds but had omitted to check that the flex temperature written on the TOLD card matched that in the FMS.
Normally by the time they are getting to the third set of amended numbers, the first officer would start a new TOLD card. However, as it was approaching the scheduled departure time, the first officer elected to overwrite the existing figures. The captain further commented that in future, if there were any more than two corrections made to the supplement data on the TOLD card, they would write out a new card.
The captain commented that this incident provided a good example of how adherence to standard operating procedures helps to mitigate errors. While the initial crosscheck prior to taxiing showed a discrepancy between the TOLD card and FMS EPR values, as it was within the permitted tolerance, the flex temperature error was not identified at that time. When the first officer checked the thrust (and EPR) during the take-off run, the too-low EPR setting was identified and the thrust levers set to obtain the correct EPR. Hence following the standard operating procedures provided sufficient risk control to identify and correct the error.
Tiredness
The flight crew signed on at 0505 for a four-sector flight duty from Sydney. The scheduled departure time for their first flight from Sydney was 0620 and the flight crew were required to sign on 1 hour and 15 minutes prior. In addition, the crew had to allow 30 minutes to transfer from the long-term carpark, pass through airport security, and sign on in the crew room in the domestic terminal at Sydney Airport.
The captain reported waking up at 0340 and the first officer at 0305, and both crewmembers reported conducting a self-assessment of their fitness to fly. The first officer reported feeling ‘somewhat tired’ having had a broken night’s sleep, but had the previous four days off work and did not feel fatigued. The captain also reported feeling tired having woken up early, they assessed they were not fatigued, and were fully fit to fly. Both the captain and first officer commented that the early start times generally caused a feeling of tiredness, but did not affect their ability to operate the aircraft.
Cobham operates flight and duty time limitations based on Civil Aviation Order 48 and an exemption, and had not, nor was required to have, implemented a fatigue risk management system. The flight crew reported that the company operations manual included a statement that it is the flight crew’s responsibility to determine their fitness to fly.
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
As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:
Communication to flight crew
The operator will remind pilots to use a new TOLD card in the event that the card data is being changed and comprehension of these changes is not clear. Pilots will be advised of the investigation by its inclusion in the company’s staff safety magazine.
Safety message
Inaccurate take‑off reference data has potentially serious consequences. ATSB Aviation Research and Analysis Report AR-2009-052 (Take-off performance calculation and entry errors: A global perspective) documents a number of accidents and incidents where take‑off performance data was inaccurate. The report analyses those accidents and incidents, and concludes:
… it is imperative that the aviation industry continues to explore solutions to firstly minimise the opportunities for take‑off performance parameter errors from occurring and secondly, maximise the chance that any errors that do occur are detected and/or do not lead to negative consequences.
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 data input errors.
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
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] Flex temperature is a calculated outside temperature used for a reduced thrust take-off. The flex temperature (which is hotter than actual outside temperature) is used for generating take-off parameters rather than the actual outside temperature. It takes into account the runway length and aircraft weight to ensure the aircraft can take off within the runway distance available and maintain the required obstacle clearance during the subsequent climb. The aim is to prolong engine life.
[2] The engine pressure ratio, or EPR, is a pressure ratio indicative of engine thrust. The pressure is sensed by two probes, one ahead and one aft of the jet engine fan.
[3] Take-off reference speeds or V speeds assist pilots in determining when a rejected take-off can be initiated, and when the aircraft can rotate, lift-off and climb.
[4] For a dry runway, the V speeds used would have been automatically generated by the flight management system.
[5] 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 aircraft flight path.
[6] A change in bleed configuration, such as selecting air conditioning packs on or off, can change the EPR value. Therefore there is a small discrepancy allowed while parked and during taxi, but the two figures must match at take-off
[7] For a precision approach, the minima is defined as a decision altitude at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.
On Monday 27 June 2016, the Indonesian National Transportation Safety Committee (NTSC) commenced an investigation into damage sustained by ATR 72 aircraft, registered PK-WGL. Initial examination of this damage suggested similarities with that found on an Australian-registered ATR 72, registered VH-FVR, which is being investigated by the ATSB (see ATSB investigation AO-2014-032 at ATSB website). On 29 June 2016, the NTSC requested the appointment of an ATSB accredited representative to the NTSC investigation in accordance with clause 5.23 of Annex 13 to the Convention on International Civil Aviation Aircraft Accident and Incident Investigation. This was a result of the ATSB’s experience with the ATR during investigation AO-2014-032 and an accredited representative was appointed to the NTSC investigation that day. To facilitate this support, the ATSB initiated an investigation under the Australian Transport Safety Investigation Act 2003.
The ATSB has completed their role in assisting the Indonesian NTSC.
The NTSC is responsible for, and will administer the release of the final investigation report into the occurrence involving PK-WGL. Any enquiries regarding the NTSC investigation should, in the first instance, be directed to the:
National Transportation Safety Committee Ministry Of Transportation Republic Of Indonesia Transportation Building 3rd Floor Jalan Medan Merdeka Timur No. 5 Jakarta Pusat 10110 Indonesia
On 21 June 2016, a Qantas Airways Boeing 747-438 aircraft, registered VH-OJS, operated flight QF11 from Los Angeles, California, United States to New York, New York, United States.
At about 0700 Coordinated Universal Time (UTC), a cabin crewmember responded to a request for assistance from a passenger seated in business class seat 3A. The passenger advised the crewmember of a missing personal electronic device (PED). The PED was identified as containing a lithium type battery. The crewmember, along with the passenger, searched around the seat for the missing PED. While searching, the seat position was moved. As the seat moved, the passenger in the next seat observed the PED within the seat mechanism. The seat was then inadvertently moved, resulting in the PED being crushed (Figure 1). The crushed PED immediately began hissing and emitting smoke. Moments later, the PED ignited. A second crewmember then initiated the basic fire drill.
The second crewmember obtained a fire extinguisher, and as they proceeded toward seat 3A, they advised a third crewmember of the incident and requested assistance. This crewmember also obtained a fire extinguisher and proceeded toward seat 3A. The customer service manager (CSM) and another crewmember observed the activity and also followed, providing additional support.
When the cabin crewmembers carrying fire extinguishers arrived at seat 3A, they observed an orange glow emanating from the seat. A crewmember discharged a fire extinguisher into the seat, extinguishing the glow. At this time, the CSM acted as a communicator with the flight crew to inform them and keep them updated on the incident.
After confirming the PED fire had been extinguished, the cabin crew attempted to remove the PED in order to place the device in water, in accordance with lithium type battery fire procedures. The PED could not be removed without further damage and risk of fire. Therefore, the cabin crew elected to leave the device in place and position a crewmember with a fire extinguisher near seat 3A for the remainder of the flight. About 10–15 minutes after the incident, this crewmember identified further heat coming from the crushed PED. They again discharged the fire extinguisher onto the PED, eliminating the heat.
After confirming the incident was contained, the CSM advised the captain that the situation was under control. The captain discussed the incident with the first officer and considered the event had been dealt with appropriately. The flight proceeded to New York and landed about 40 minutes later without further incident.
Two passengers reported feeling unwell after the event, but it was unclear if this was as a result of the incident. The aircraft seat sustained minor damage.
Figure 1: Crushed PED after removal from seat
Source: Qantas
Cabin crew comment
The responding cabin crewmember commented that the provision of designated storage close to the charging port could assist in preventing PEDs entering seat structure.
Passenger comment
The passenger in seat 3A commented that the amenities pack provided to passengers in this seat type could be changed to include PED storage. This could assist preventing PEDs entering the seat structure.
Operator investigation report
The aircraft operator investigated the incident and provided a copy of their investigation report to the ATSB. The report included the following:
A review of reported events revealed 22 similar occurrences of trapped or crushed PEDs. Seven of these occurrences resulted in smoke and/or heat being produced. This incident was the first event to result in fire.
The investigation determined that the likely area for the PED to intrude into the seat mechanism was adjacent to the seat belt anchor point. This area becomes more exposed as the seat reclines towards the flat position.
Mesh netting within the seat structure is designed to capture objects that fall behind the seat. Damage to seat 3A consisted of an approximate 5 cm melt area to this mesh netting. There was no other damage noted to the seat structure.
Lithium batteries are capable of ignition and subsequent explosion due to overheating. Overheating may be caused by shorting, rapid discharge or overcharging. Overheating results in thermal runaway, which is a chemical reaction within the battery causing the internal temperature and pressure to rise. The result is the release of flammable electrolyte from the battery and, in the case of disposable lithium batteries, the release of molten burning lithium. Once one battery cell goes into thermal runaway, it produces enough heat to cause adjacent battery cells to also go into thermal runaway. This produces a fire that repeatedly flares up as each battery cell in turn ruptures and releases its contents.
SAFO 09013 Supplement also details the following information on fighting fires caused by lithium type batteries:
Relocate passengers away from the device.
Utilise a halon, halon replacement, or water fire extinguisher to prevent the spread of the fire to adjacent battery cells and materials.
Pour water, or other non-alcoholic liquid, from any available source over the cells immediately after knockdown or extinguishment of the fire.
Only water or other non-alcoholic liquid can provide sufficient cooling to prevent re-ignition and/or propagation of the fire to adjacent batteries. Water, though it may react with the tiny amount of lithium metal found in a disposable battery, is most effective at cooling remaining cells, stopping thermal runaway and preventing additional flare-ups. Significant cooling is needed to prevent the spread of fire to additional cells in a battery pack.
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.
Seat manufacturer
As a result of this occurrence, the aircraft operator has advised the ATSB that the seat manufacturer is developing design solutions to prevent ingress of PEDs into the seat structure.
Aircraft operator
The aircraft operator has advised the ATSB that they are taking the following safety actions:
Changes to passenger briefings
An enhanced passenger briefing has been released to include:
If you lose your electronic devices at any time, it’s important you don’t move your seat as this could severely damage your device and may be a fire hazard. Please contact a crew member who will be able to recover your device.
A cabin crew service brief has been released which includes:
Passenger announcement to remind passengers not to move seats when devices have been lost.
Individual interactions between cabin crew and passengers when preparing the bed to include a discussion to raise passenger awareness of the possibility that the PED could be crushed if it is lost during the flight.
Establishment of working group
A working group has been established to develop further solutions for this issue.
Safety message
This incident serves as an excellent example of an effective response to an emergency situation. The cabin crew quickly implemented the basic fire drill procedure. This defined the roles and responsibilities of the responding crew, enabling a rapid and coordinated response to the incident using all available resources. As a result, the incident was quickly and effectively contained. The effective implementation of this procedure also ensured the flight crew were kept informed as the situation developed.
This incident also highlights the hazards of transporting lithium-ion battery powered PEDs aboard aircraft. The Civil Aviation Safety Authority has released information on the safe carriage of lithium type battery powered devices aboard aircraft in the web page: Travelling safely with batteries and pamphlet: Is your luggage safe?
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
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.
Occurrence summary
Investigation number
AO-2016-066
Occurrence date
21/06/2016
Location
500 km WNW of John F. Kennedy International Airport, United States
On 27 June 2016, the pilot of an Airparts (NZ) FU-24-950 aircraft, registered VH-TTD, was conducting agricultural operations from an airstrip about 50 km east-south-east of Tamworth Airport, New South Wales. The pilot was the only person on board the aircraft.
The airstrip elevation was about 3,200 ft and sloped downhill in the direction used for take‑off, with a steep slope at the end of the runway. The surrounding terrain was below the elevation of the airstrip and the first obstacle in the take-off direction was a fence at the end of the runway.
At about 1130 Eastern Standard Time (EST), after having completed about 35 flights for that morning, the pilot started their next take-off run with the flaps[1] in the normal take-off setting of 20°. The aircraft handled normally until shortly after lift-off, when at an airspeed of about 60 kt, the pilot heard a ‘bang’. The aircraft sank rapidly and the tail struck the runway surface. As the runway sloped steeply downhill, the aircraft became airborne again. Due to the proximity of the fence at the end of the runway, the pilot elected to continue the take-off and dump the fertiliser load. As the load was being dumped, the aircraft struck the fence, but continued to fly.
The pilot quickly detected that there was no response from the elevator[2] to their control inputs. They could move the control column fore and aft, but the aircraft pitch[3] did not respond. They also observed that the flap was fully retracted even though the cockpit flap lever was still set to 20°. The pilot elected to divert to Tamworth Airport, which was below the elevation of the airstrip. The pilot used engine power and elevator trim[4] to control the pitch of the aircraft.
The pilot contacted Tamworth air traffic control (ATC) and informed them that they had a ‘bit of an issue’. They also advised that they had no elevator control, but still had the aircraft under control (Figure 1). ATC cleared the pilot to manoeuvre as required to approach and land on the main runway at Tamworth.
The pilot conducted a long and low straight-in approach to runway 12 left at Tamworth with the aircraft trimmed in the approach attitude, which was slightly nose up. At about 10 ft above the runway, the pilot reduced the throttle to idle for the landing. The aircraft then pitched nose down and the nose wheel contacted the runway first and burst the nose wheel tyre. The aircraft stopped on the runway with minor damage and the pilot was not injured.
Figure 1: VH-TTD flying towards Tamworth Airport on the incident flight
Source: BAE Systems Flight Training Tamworth
Repair organisation findings
The repair organisation that performed the post-incident inspection found damage to the propeller, tailplane and underside of aircraft consistent with impact with the runway and fence during the take-off. A detailed inspection inside the airframe revealed the following:
The structural frame supporting the lower elevator control cable pulley was pushed up about 10 cm (Figure 2).
The centre section just aft of the hopper (Figure 3) had about 12 mm of water in it and the drain hole for the centre section was blocked by fertiliser. The repair organisation assessed that the size of the drain hole was inadequate and that a larger hole with a removable bung would be preferable.
The flap control cable had failed at the rear flap pulley and the failure appeared to be due to corrosion (Figure 4).
Figure 2: VH-TTD elevator control cable pulley
Source: Repair organisation and BAE Systems Flight Training Tamworth annotated by ATSB
Figure 3: VH-TTD centre section
Source: Repair organisation annotated by ATSB
Figure 4: VH-TTD broken flap cable
Source: Repair organisation annotated by ATSB
Maintenance schedule
The aircraft system of maintenance used was the Civil Aviation Safety Authority (CASA) Schedule 5 with 100-hourly periodic inspections. CASA Schedule 5 includes the following inspections relevant to this incident:
Item 3 (j) for the airframe periodic inspection: ‘inspect the control wheels, control columns, rudder pedals, control levers, control system bellcranks, push pull rods, torque tubes and cables.’
Item 17 for the daily inspection: ‘check that the drain holes are free from obstruction.’[5]
Previous maintenance inspections
The last 100-hourly periodic inspection was certified on 19 May 2016 in accordance with CASA Schedule 5. The previous periodic inspection was on 21 April 2016, and a corrosion inspection was performed on 23 November 2015, which included CASA Airworthiness Directive
. No findings were recorded against the flap control cable for these inspections. During the periodic inspections, the flap cable was inspected by moving a cloth along the cable and no broken strands were detected, and there was no water present in the centre section of the aircraft aft of the hopper. However, the maintenance organisation indicated that they did not remove the flap cable for inspection, nor apply corrosion protection to the flap cable during the inspections.
Recommended practices
CASA Airworthiness Bulletin 27-001 issue 7 includes the following recommendation:
…flight control cables should be periodically inspected in accordance with manufacturer’s data and FAA AC 43-13-1B Chapter 7, AIRCRAFT HARDWARE, CONTROL CABLES AND TURNBUCKLES, section 8, paragraph 7.149d. To inspect all surfaces of a cable throughout its entire length for wear and fatigue (broken wires) usually requires that the cable be disconnected and removed...
United States Federal Aviation Administration Advisory Circular 43-13-1B chapter 7, section 8, paragraph 7.149 states that: ‘deterioration, such as corrosion, is not easily seen, therefore, control cables should be removed periodically for a more detailed inspection and any cable with a broken strand in a critical fatigue area[6] must be replaced.’ See Figure 5 below.
Paragraph 7.149i states that: ‘Areas especially conducive to cable corrosion are battery compartments…etc.; where a concentration of corrosive fumes, vapours, and liquids can accumulate.’
Paragraph 7.152 states that where control cables pass over pulleys: ‘Provide corrosion protection for these cable sections by lubricating with a light coat of grease or general purpose, low-temperature oil.’
Figure 5: Cable inspection technique
Source: FAA AC 43.13-1B page 7-35
ATSB comment
The ATSB notes that the corrosion present on the flap control cable at the location of the failure takes a considerable amount of time to develop. The corrosion was confined to the working length of the cable that was in contact with the flap control system rear pulley, which is considered to be a critical fatigue area. The failed cable was comprised of woven steel wires plated with zinc or tin. The cable was confirmed to be the correct type for the application.
Over time, in the absence of a suitable lubricant, the plating can wear due to frictional contact with the pulley. This will render the cable susceptible to corrosive attack and elevate the likelihood of a fatigue failure. The flap control cable was not removed during the last periodic inspection, which could have detected the corrosion damage. Nor was grease applied to the working length of the cable, or the rear flap pulley, during the last few inspections to mitigate against the development of corrosion.
Entrapped water, fertiliser and potentially, the previous use of an unsealed lead-acid battery,[7] all contributed to a corrosive environment within the centre section of the aircraft, and corrosion of the flap cable.
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.
Maintenance organisation
As a result of this occurrence, the maintenance organisation has advised the ATSB that they are taking the following safety actions:
Maintenance practices
The FU-24 rear flap control system pulley will be removed during CASA Schedule 5 periodic inspections to facilitate inspection of the flap control cable.
Safety message
This incident highlights the need for maintenance organisations to periodically review the recommended practices published by both the manufacturer and the regulatory authorities. The Schedule 5 system of maintenance details what inspections are required, but does not prescribe how they should be performed. Reference to the relevant industry standard practices can improve the quality of maintenance conducted and ensure an organisation’s practices remain up-to-date with the respective standards, which are periodically updated to incorporate new knowledge.
For further background information on flight control cables and terminals and their failure modes, refer to CASA
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
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.
On 18 June 2016, at about 0136 Western Standard Time (WST), the pilot flying and a check pilot (who was the pilot in command) of a Pilatus PC-12 47E aircraft, registered VH-OWA (OWA), prepared to conduct a medical retrieval flight from Meekatharra Airport to Paraburdoo, Western Australia, under the instrument flight rules.[1] Due to the remote area, the terrain surrounding the airport was dark, although the night was moonlit. The pilot flying was seated in the left seat, the check pilot in the right seat, and a flight nurse was also on board.
The pilot flying completed the pre-start, start and after-start checks. As the aircraft had been parked under a metal roof, the aircraft’s two GPS units had not acquired enough satellites to complete their initialisation. The pilot flying therefore taxied the aircraft a short distance onto the taxiway before stopping. GPS 1 located all satellites as required, but GPS 2 failed to initialise and the crew received an UNABLE FMS-GPS MON caution message.[2] The pilot flying followed the quick reference handbook actions in response to that message, following which GPS 2 initialised and the caution cleared. The pilots then continued for a normal take-off from runway 09, at about 0145.
About 18 seconds after take-off, as the aircraft climbed through about 250 ft above ground level at an airspeed of about 110 kt, the pilots observed the radio altimeter (radalt) wind down to zero (see Radio altitude). The radalt low altitude awareness display rose to meet the altitude readout.
The synthetic vision image (see Synthetic vision system) on both pilots’ primary flight displays (PFDs) then showed the runway move rapidly left and off the screen, and the ground representation on the PFD appeared to rise rapidly up to meet the zero pitch reference line (ZPRL).[3] As a result, the pilot flying pulled back on the control column and the flight data showed the flight path indicator (see Aircraft reference symbols) moved up to about 15°. No warnings or cautions were displayed, the stick shaker stall warning did not activate (as the aircraft angle of attack was not in the shaker range), and the crew did not receive any oral alerts from the terrain awareness and warning system (TAWS).
The pilot flying reported that the synthetic vision image created the impression that the aircraft was sinking rapidly towards the ground, and they responded by instinctively pulling back on the control column. There was no vestibular sensation[4] that the aircraft was descending, nor had there been any indication of a strong wind that may have caused the aircraft to drift off the runway centreline. The resulting sensory confusion caused the pilot flying to experience a level of motion sickness.
The check pilot immediately looked outside (there was no standby instrument on the right side of the cockpit), and was able to discern a visible horizon due to the moonlight. The check pilot cautioned the pilot flying that the aircraft had a nose-high attitude, which prompted the pilot flying to switch their focus to the electronic standby instrumentation system (ESIS) and closely monitor the attitude and the airspeed tape (see Electronic standby instrumentation system). The pilot flying lowered the aircraft nose to regain an 8° pitch[5] attitude and the flight data showed that the airspeed, which had reduced to 101 kt, increased back to the target airspeed of 110 kt. The aircraft had continued to climb throughout the event.
Climbing through about 850 ft, the synthetic vision display corrected itself and all indications returned to normal. After retracting the landing gear and flap, the pilot flying deselected the synthetic vision mode on the left PFD. The check pilot continued to monitor the synthetic vision on the right PFD, and the issue did not recur during the flight. The aircraft subsequently landed at Paraburdoo Airport without further incident.
Flight data analysis
The flight data was downloaded from the aircraft condition monitoring system and analysed by the ATSB. Figure 1 depicts the calibrated airspeed and pitch angle from the start of the take-off roll. The change in pitch (pink line) from the pilot pulling back on the control column in reaction to the synthetic vision started at about 0145:30 in Figure 1.
Figure 1: Plot of selected data from the incident flight
Source: Aircraft flight data analysed by ATSB
Figure 2 shows the aircraft recorded GPS track, with the pink marker indicating the first significant increase in pitch attitude, and therefore the approximate point of radalt failure. The aircraft was then at about 250 ft above the runway.
Figure 2: Deviation of OWA (travelling from left to right) from runway centreline showing the estimated point of the radalt failure (in pink)
Source: Google earth and aircraft flight data analysed by ATSB
Incorrect instrument indications
After the incident, an engineering assessment determined that both antennas associated with the radalt system (one for transmit and one for receive) had failed, and had been in service for over 9,000 hours. The antennas did not have a life limit, but were required to be replaced ‘on condition’, which essentially meant that the antennas remained in service until they failed. After consultation with the avionics manufacturer, engineers replaced both radalt antennas and also the radar transmitter/receiver. No subsequent similar event has occurred on the aircraft. The engineers also replaced the GPS 2 antenna due to slower than normal acquisition of satellite navigation after power up, and updated the GPS databases, although it was considered that these did not contribute to the incident.
The engineers reported that this failure of the radalt antennas was likely to have resulted in the radalt winding down to zero, and the radalt low altitude diagonal bars to appear on the altitude tape to show the aircraft was close to the ground (below 550 ft) (see Figure 4 in Radio altitude below). Additionally, the radalt information was used in conjunction with the runway (and obstacle) information in the database to provide the synthetic vision system display. This resulted in the runway appearing to rise up towards the aircraft reference symbol on the PFD.
The movement of the runway to the left of the screen was probably associated with a small displacement of the aircraft to the right of the runway centreline. The wind at the time was from 094° at 9–11 kt, therefore largely a headwind component and the lateral displacement of the aircraft was unlikely to be a result of the wind.
As the radalt senses that the aircraft is nearing the ground, smaller lateral deviations from the runway centreline generate significant movement of the synthetic vision runway image.
Radio altitude
The radalt display is shown in green numbers on the PFD when the radalt data is valid and less than 2,500 ft (Figure 6). If the radalt data becomes invalid, the radalt digital readout is replaced with a radar altitude data (‘RAD’) annunciator and an amber RA 1 FAIL crew alerting system (‘CAS’) message is displayed. The crew did not receive any annunciations during this incident to indicate that the radalt had failed.
When the altitude displayed on the radalt is below 550 ft above ground level, low altitude awareness is displayed using diagonal yellow lines (Figure 3). During this incident, the crew noticed that the low altitude awareness symbology was displayed.
Figure 3: Radalt low altitude awareness display
Source: Honeywell
Synthetic vision system
The synthetic vision system fitted to the aircraft is depicted in Figure 4. It supplies a three-dimensional view of surrounding terrain, obstacles and runways based on a terrain database. Normal attitude, altitude and airspeed information is overlayed on top of the terrain display. The TAWS terrain database provides geometric altitude (obtained from the GPS) in order to display synthetic vision terrain and terrain related items such as runways and obstacles. During this incident, the synthetic vision system provided no failure annunciations.
Figure 4: Synthetic vision system example display
Source: Honeywell
Figure 5 shows a sample image of the runway scale for an aircraft on final approach for reference.
The synthetic vision system was not to be used for primary input or navigation, with the following warning issued by Honeywell in the Pilot’s Guide (used by the operator) to the avionics system:
A similar warning was contained in the Primus Apex Smart View supplement to the aircraft flight manual.
Both crew reported they were aware that the synthetic vision should not be used for primary navigation. When installed, the synthetic vision system is automatically activated at start-up but can be deselected by the pilot.
Aircraft reference symbols
The pilot flying was using the flight path indicator on the synthetic vision system. This consists of the flight director command bars (magenta symbol in Figure 6) and the flight path aircraft reference symbol (green symbol in Figure 6). The flight path indicator is a path-based mode and depicts the aircraft’s predicted flight path (not just aircraft pitch) and is affected by pitch attitude and the aircraft’s ground speed. It shows flight path angles[6] – up for increasing and down for decreasing flight path angles, whereas the traditional pitch-based mode depicts aircraft pitch angle. The flight path angle depicted in Figure 6 is -4°.
Figure 6: Synthetic vision and flight path indicator symbols
Source: Honeywell
Electronic standby instrumentation system
An electronic standby instrumentation system (ESIS) (or electronic standby indicator (ESI)), was fitted to the left of the pilot flying’s PFD. Figure 7 shows the pilot’s side PFD with the ESIS to the left of the main screen in another Pilatus PC-12 aircraft (not OWA). Note in this photo, the synthetic vision is on and the aircraft is over water.
Figure 7: Electronic standby indicator and main PFD in flight (not OWA)
Source: ATSB
Pilot comments
The two pilots were highly experienced; the pilot flying had over 11,000 hours total aeronautical experience and over 2,600 on the aircraft type, and the check pilot had over 15,000 hours total experience and 3,000 hours on type.
Both pilots commented that they had previously experienced failure of primary flight instruments at low level and at night in different aircraft (without synthetic vision systems). They had been able to disregard the erroneous or failed instruments and reference the standby instruments to maintain control of the aircraft and situational awareness. However, the prominence of the synthetic vision display is such that it is difficult to ignore erroneous information and locate valid information. Additionally, the pilot flying reported feeling a level motion sickness, probably associated with the combined effects of the prominent synthetic vision display and conflicting vestibular sensory information.
The combination of the runway and the radalt speed tape moving up gave the very strong illusion that the aircraft was going to hit the ground. The pilot flying reported that they realised something was wrong but could not initially figure out what it was. The image of the ground rising up and the runway disappearing rapidly sideways took the focus of the pilot flying away from anything else.
The pilot flying commented that the check pilot’s caution ‘attitude’ helped to redirect the pilot flying’s attention to the standby indicator. The check pilot could not easily see the standby indicator. Both pilots commented that the situation may have been more serious if operating single pilot or if they had already flown more sectors that night and been more tired.
The pilots commented that it was impossible to discern the valid attitude information on the PFD (overlaid on top of the synthetic vision) and revert to flying ‘power and attitude’ given the prominence of the erroneous synthetic vision information. While it is possible to deselect the synthetic vision, it requires two button presses or the use of the cursor control device to do so. That is very difficult to do at low level while maintaining control of the aircraft – keeping the right hand on the thrust lever and the left hand on the control column.
The Pilot Advisory Letter issued in response to this incident (see Safety action) reminded pilots to look at the primary flight indications presented on the PFD at all times. The pilot flying commented that it should refer pilots to the standby attitude indicator instead. The screen at the time of failure was simply too confusing to start looking for two small, white attitude bars. Similarly, to break the fixation on the erroneous information, it is important to look somewhere else at a different instrument – the standby indicator.
Most of the pilots’ training is done on board the aircraft, as they do not have access to a Pilatus PC-12 simulator. Although some system failures can be simulated, it is not possible to generate a false display as occurred in this incident.
Spatial disorientation
Spatial disorientation can occur when visual cues provide sensory inputs that are not matched by the motion sensed by the pilot through the vestibular senses. The discrepancy between the visual display showing the aircraft apparently descending towards the ground, and the lack of any consistent physical sensation, led to disorientation. The flight was conducted at night, and the pilot flying did not look outside for a visual reference. The check pilot did look outside and found that there was enough moonlight to provide some visual reference, sufficient to show the aircraft pitch and roll attitudes relative to the horizon.
ATSB research report ‘An overview of spatial disorientation as a factor in aviation accidents and incidents’describes this type of spatial disorientation as ‘recognised’. That is, the pilot identified that they were sensing erroneous information. The conflict between their own perceptions and that given by the instruments alerted them to a problem, which they were then able to address. However, the crew reported feeling some level of disorientation stress, or motion sickness, which is indicative of a disagreement between the senses.
The visual system provides around 80 per cent of orientation information, hence the overriding presence of incorrect visual information deprived the pilots of the majority of orientation information.
Other factors such as tiredness or fatigue, and high workload, can contribute to a pilot’s ability to assess and effectively deal with spatial disorientation. Both pilots commented that they wanted to share their experience because if they had been operating single pilot or near the end of a long shift, recovery from the instrumentation failure may have been much more difficult.
In addition, if the outside light conditions had been completely dark due to a lack of any moonlight in an area without terrain lighting, or the aircraft was in cloud, recognition of the spatial disorientation would have been reliant on the pilots being able to either extract the basic attitude, altitude and airspeed information from the primary display ignoring the background image, or revert to the accurate information depicted on the smaller standby indicator.
Pilots operating under instrument flight rules are trained to focus their attention on the visual information presented by the aircraft instruments and to ‘believe’ that information rather than the sensory information from the vestibular system, which can provide misleading cues.
The ATSB research report further states that:
…instrumentation should present a clear and intuitive sense of position, which the pilot under conditions of high stress and workload can instantly achieve an idea of what the aircraft is doing.
Failure of the aircraft instruments should hopefully never occur. However, in the event that it does, the pilot needs to receive clear and non-ambiguous indications of instrument failure. If a key instrument fails, such as the attitude indicator, the pilot needs to know that it has failed so they no longer depend on its information.
Manufacturer investigation
An investigation by the synthetic vision system manufacturer, Honeywell, found that the radio altimeter sent incorrect radio altitude data to the synthetic vision system while still indicating that the data was valid. Therefore, the synthetic vision display system continued to display the terrain information using incorrect data.
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 aircraft operator has advised the ATSB that they have taken safety actions including the following:
Engineering replaced the RADALT aerials across the fleet.
The minimum equipment list has been amended to include synthetic vision.
Flight crew were alerted to the potential hazard of a synthetic vision failure during flight through a safety communication on 1 July 2016. The potential for confusion or spatial disorientation during an event, particularly at night or in low visibility environmental conditions was highlighted.
The event has been discussed by the Training and Check Department. They are reviewing the possibilities of incorporating scenarios related to ambiguous/incorrect information from the primary flight display into check flights and have commenced trialling a scenario.
Honeywell – avionics manufacturer
As a result of this occurrence, the avionics system manufacturer has advised the ATSB that they are taking the following safety actions:
Pilot advisory letter
Honeywell issued a Pilot Advisory Letter (PAL-APEX-01) to all pilots, chief pilots and flight operations managers on 11 August 2016. The letter included a description of the event. The letter also advised pilots that the use of synthetic vision is for situational awareness and should not be utilised for the indication of attitude or altitude in lieu of the primary flight display indications for pitch, roll, yaw, or altitude. The letter advises pilots to follow the primary flight indications presented on the PFD at all times.
The letter was also made available on the Pilatus ‘my pilatus’ website and all subscribers to that website were notified by email.
System solution
Honeywell is investigating ways to make the synthetic vision system more robust against a similar failure. The focus of their investigation is to prevent the synthetic vision display from continuing to display the image when the data is incorrect but assessed as valid by the Radalt.
Safety message
Incorrect instrument indications that are not associated with a failure mode present pilots with a complex and challenging situation. This situation may be exacerbated during single-pilot (rather than multi-crew) operations, where there is a lack of external visual references (such as at night or in instrument meteorological conditions), under high pilot workload conditions, or where a pilot is experiencing an elevated level of fatigue.
The image of terrain on the primary flight display is powerful and compelling. This incident highlights the manner in which an inaccurate synthetic vision image can rapidly lead to a degree of spatial disorientation. Pilots need to ensure that they are familiar with the limitations of the synthetic vision system and how to effectively deal with erroneous information as well as system failure modes. Organisations that operate aircraft fitted with similar technology should ensure that appropriate information and training is available to pilots, including when and how it should be used when it is not approved for primary navigation.
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
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.
On 21 March 2016, a Cessna 172L, registered VH-XZZ, disappeared from radar about 7 NM (13 km) north-east of Byron Bay, New South Wales (NSW). The pilot was the sole occupant and, despite initial search efforts, the aircraft was reported as missing.
The accident is being investigated by the NSW Police Force on behalf of the NSW Coroner. The ATSB did not initiate a separate accident investigation; however, on 14 June 2016, the police advised the ATSB that the wreckage had been located and video recorded by the Royal Australian Navy. In addition, the police requested ATSB assistance with their examination the video footage of the wreckage.
To facilitate this support, on 15 June 2016 the ATSB initiated an external investigation under the provisions of the Transport Safety Investigation Act 2003. The ATSB completed its review of the video footage and provided a report to the NSW Police Force on 30 August 2016.
Any enquiries as to the planning for, or conduct or progress of the Coroner’s investigation into this accident should be directed to the:
State Coroner’s Court of New South Wales 44–46 Parramatta Road Glebe NSW 2037
Phone: (02) 8584 7777
_________________
The information contained in this web update is released in accordance with section 25 of the Transport Safety Investigation Act 2003.
At about 0738 Central Standard Time (CST), a Cessna 172 aircraft, registered VH-EKV (EKV), taxied to depart from runway 12 at Alice Springs Airport, Northern Territory for Ayers Rock. The pilot and two passengers were on board the private flight. The air traffic control Tower was scheduled to open at 0800. At the time of departure, procedures for operating in the vicinity of non-controlled aerodromes applied at Alice Springs Airport. The airport has a common traffic advisory frequency (CTAF) when the Tower is closed.
The aircraft was located on the general aviation apron and taxied for holding point bravo for runway 12 (yellow line in Figure 1). The pilot of EKV broadcast a taxi call on the CTAF.
Figure 1: Alice Springs Airport showing the taxi routes and relevant locations of EKV (yellow line) and MLB (orange line)
Source: Google earth, modified by the ATSB
The transcripts of the relevant CTAF recordings are shown below, with the time, who made the broadcast, the transmission, and readability.[1]
Time
Source
Broadcast
Readability
0738:26
EKV
All stations EKV Cessna 172 taxiing for the runway 12 [AFRU[2] ‘Alice Spring CTAF’]
5. Perfectly readable
Following the broadcast by the pilot of EKV, several broadcasts were made on the CTAF where the airport rescue and firefighting service were conducting routine radio checks.
At 0741:15, the pilot of a Beech 58 aircraft, registered VH-MLB (MLB), broadcast a taxi call on the CTAF (the readability was 2, as the call was badly broken and very hard to understand). The aircraft was located on the commuter apron and taxied for holding point echo with the intention of then backtracking on the runway in preparation for a runway 30 departure (for a flight to Nyirripi) (orange line in Figure 1). The pilot and two passengers were on board the charter flight.
0741:15
MLB
Alice springs traffic MLB taxiing and backtracking runway 30 for Nirripi Alice Springs [AFRU tone]
2. Readable now and then
At 0741:25, the pilot of EKV broadcast that they were lining up on runway 12 (Figure 1).
0741:25
EKV
EKV lining up on 12 [No AFRU tone]
5. Perfectly readable
The pilot of MLB reported that they did not hear this broadcast from EKV, nor the earlier broadcast that they were taxiing for runway 12.
At 0741:30, the pilot of a Piper PA32 broadcast a taxi call (the readability was 3, with a loud squeal). The PA32 was located at the general aviation apron, close to where EKV had taxied earlier, and was taxiing for runway 12.
0741:30
PA32
Alice springs traffic [registration] taxiing runway 12 Alice Spring [AFRU tone]
3. Readable but with difficulty
The pilot of MLB responded to the broadcast by the pilot of the PA32, asking if they were happy for MLB to taxi (which included entering and backtracking the runway) for runway 30, and advised that they were ‘shortly to depart’.
0741:38
MLB
Aircraft taxiing runway 12 you happy for me to taxi runway 30 shortly to depart [No AFRU tone]
5. Perfectly readable
The pilot of the PA32 responded to that broadcast by indicating that they would hold short of runway 12.
0741:43
PA32R
Affirm [registration] will hold short [No AFRU tone]
4. Readable
The pilot of MLB responded, thanking the pilot of the PA32.
0741:47
MLB
MLB thank you [No AFRU tone]
5. Perfectly readable
Following this exchange between the pilot of the PA32 and the pilot of MLB, several broadcasts were made on the CTAF, where the airport fire and rescue service were conducting radio checks (at 0741:53, 0741:59, and 0742:02).
The pilot of MLB approached holding point echo and reported looking for other aircraft on approach or lined up on either runway (12 or 30). The pilot of MLB did not see any other aircraft and had not heard any other aircraft on the CTAF except for the PA32, so entered the runway and commenced backtracking runway 30 (orange line in Figure 1).
At about the same time, the pilot of EKV commenced take-off on runway 12. At about take-off speed, the pilot reported observing another aircraft enter the runway and start taxiing on runway 12 (away from them). The pilot assessed that it would be more dangerous to stop, so continued with the take-off.
An air traffic controller arrived in the control tower (which was due to open at 0800) and observed a Cessna 172 aircraft (EKV) taking off on runway 12 and a Beech 58 aircraft (MLB) taxiing on the same runway, about half way down the runway (Figure 1). The controller advised the pilot of EKV to stop immediately.
The pilot of EKV reported not hearing the advice to stop immediately, but was busy with the take-off. The controller reported that EKV was airborne approximately 500 m before the position of MLB and passed overhead MLB at about 150 feet above ground level. The pilot reported banking the aircraft to the north at about 500 feet and two-thirds of the way down the length of the runway to avoid any possible conflict with the aircraft (MLB) on the runway.
The pilot of MLB heard the controller’s advice to another aircraft to stop, but was not aware of the reason. During the turn at the end of the runway to line up on runway 30, the pilot noticed a Cessna 172 (EKV) in a left turn toward the north. The pilot broadcast on the CTAF for the aircraft in the Alice Springs circuit area to notify their intentions.
0743:57
MLB
Aircraft in circuit area at Alice Springs MLB just request your intentions [AFRU tone]
5. Perfectly readable
The pilot of EKV then gave a departure call at 0744:14 (readability was 4).
0744:14
EKV
EKV on climb to 3,000 departed time 14 [AFRU tone]
4. Readable
The pilot of MLB believed that the pilot of the Cessna 172 (EKV) had responded to their broadcast, and reported that the readability from the Cessna 172 was very poor. The pilot of MLB responded to the Cessna 172 at 0744:27, but that broadcast was over-transmitted by another aircraft making a taxi broadcast.
The next broadcast recorded from MLB was at 0747:19, where the pilot broadcast a departure call. The pilot reported having made lining-up and holding broadcasts, which may have been over-transmitted, and also making a rolling broadcast that was not recorded on the CTAF.
Both aircraft departed without further incident.
Pilot comment VH-EKV
The pilot reported generally operating at Alice Springs Airport when the tower was open, so would normally communicate with the tower controller. At the time of the occurrence, the Tower had not opened and the pilot reported hearing radio calls, but commented that radio calls from aircraft were not as clear as those made from the tower controllers. The pilot was aware that there was another aircraft departing to Nyirripi (destination of MLB).
Pilot comment VH-MLB
The pilot reported identifying the location of the PA32 as they approached holding point echo. The pilot commented that there were some white buildings in the distance behind the threshold of runway 12 that may have made it difficult to see EKV. The pilot indicated that the runway, although long, it is quite flat, and the whole runway was visible. The pilot also indicated that they were focused on known traffic. The pilot recognised the aircraft registration of the PA32 and the voice of the pilot, and confirmed the location of that aircraft before entering the runway.
The pilot reported that the winds were calm. They elected to use runway 30 as it was the most convenient runway for their departure.
Radio communication - Alice Springs airport
A study was conducted in 2010 by the Civil Aviation Safety Authority (CASA) to review the airspace classification above Alice Springs, Aeronautical Study of Alice Springs (YBAS) January 2010, and is available from the CASA website. The study consulted with stakeholders and did not identify any radio transmission ‘black spots’.
ATSB comment
The relevant communication recordings for the Alice Springs CTAF were obtained by the ATSB from Airservices Australia and the relevant broadcasts were given a readability level by the ATSB using the standard in radiotelephony communications as published in the AIP. The communications recorded are not necessarily what a pilot hears in their respective aircraft.
The ATSB could not establish why the pilots of both aircraft did not hear the broadcasts from the other aircraft.
Safety message
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 such concern is Safety around non-controlled aerodromes, which highlights that it is difficult for pilots to detect another aircraft through visual observation alone. The ATSB has identified that insufficient communication between pilots operating in the same area is the most common cause of safety incidents near non-controlled aerodromes.
This incident highlights the fundamental importance of effective communication, particularly during operations at a non-controlled aerodrome. The Civil Aviation Safety Authority (CASA) has produced several publications and resources that provide important safety advice related to operations in the vicinity of non-controlled aerodromes. Relevant guidance and explanatory material provided by CASA includes the following:
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
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] As outlined in the Airservices aeronautical information publication (AIP), the readability scale is as follows: 1. Unreadable, 2. Readable now and then, 3. Readable but with difficulty, 4. Readable, 5. Perfectly readable.
[2] Alice Springs Airport has an aerodrome frequency response unit (AFRU) installed. The AFRU is to provide an automatic response to CTAF broadcasts to indicate to an operator that the correct radio frequency was selected and to confirm the operation of the radio’s transmitter and receiver, and the volume setting. If a broadcast has not been made on the CTAF in the preceding five minutes, and this transmission is over 2 seconds in length, a voice identification from the ARFU ‘Alice Springs CTAF’ is generated. If a broadcast has been made on the CTAF in the preceding five minutes, a 300-millisecond tone will be generated after each transmission over two seconds long.
