Response to Gascoyne Junction Inquest Findings
On Friday 5 July 2013 the Western Australian (WA) State Coroner released the findings of his investigation into a 2008 fatal Piper Super Cub mid-air collision with a Robinson R44 helicopter 53km north-north-west of Gascoyne Junction. The Australian Transport Safety Bureau (ATSB) has reviewed the Coroner’s findings and reaffirms the safety factors identified by its own investigation. The ATSB’s report was released on 26 June 2009.
ATSB Report
Circumstances of the Accident:
On 13 February 2008, a Piper Aircraft Corporation PA-18 Super Cub aircraft and a Robinson Helicopter Company R44 Raven helicopter were engaged in feral goat culling operations in the Kennedy Range National Park, WA. The operation was initiated by the WA Department of Environment and Conservation (DEC) who contracted the Department of Agriculture and Food, WA (DAF) to assist.
The two aircraft collided in midair as the pilot of the helicopter executed a climbing left turn that brought the two aircraft into close proximity. The pilot and shooter occupants of the R44 were aware that the Super Cub was approaching them at the same height, and the helicopter pilot was aware of the position of the aeroplane during the helicopter's climbing turn, but it appeared probable that the pilot and spotter occupants of the Super Cub did not see the helicopter.
The ATSB found that the Super Cub climbed up and through the disk formed by the helicopter’s rotor blades. The helicopter's main rotor blades struck the Super Cub's right wing, severing the lift struts. The right wing detached in flight, and the Super Cub fell to the ground. The pilot and spotter were fatally injured. The helicopter was able to land safely.
Safety Factors and Key Findings:
In its Final Report the ATSB found the following contributing safety factors:
- At about the time the two aircraft passed each other, the R44 pilot initiated a climbing left turn that resulted in the two aircraft coming into close proximity;
- The Super Cub occupants were probably unable to see the R44 during the period beginning at or about the time the helicopter commenced the climbing left turn until the collision;
- There was no alerting radio call to advise the Super Cub occupants of the R44 position and intentions;
- Only the R44 pilot was aware of the relative position of the two aircraft;
- The Super Cub pilot’s manoeuvre resulted in the two aircraft converging;
- The R44 pilot did not recognise the collision risk until there was insufficient time to prevent contact with the Super Cub;
- There were no formalised operating procedures detailing the conduct of multiple aircraft culling operations, including the assurance of aircraft separation that would have assisted the pilots maintain separation from each other [safety issue].
The ATSB also made a key finding that:
- The R44 pilot’s work schedule was unlikely to have resulted in work-induced fatigue leading to a significant performance decrement in his ability to operate the helicopter.
Coroner’s Findings
How the accident occurred:
The coroner found that at impact the R44 was rising up into the Super Cub.
The Coroner based this finding on the recollection of the shooter in evidence. In his evidence, the shooter stated that the Super Cub was higher than the R44 as the aircraft passed each other prior to the collision. The Coroner did not consider the ATSB scenario of events likely.
ATSB response:
The ATSB acknowledges the grounds for the Coroner’s finding while reaffirming its assessment that the wing of the Super cub climbed up and passed through the main rotor blade disk of the R44. The ATSB’s assessment was based on the following grounds:
- The account of the circumstances prior to the collision given by the R44 pilot to the ATSB following the accident. The shooter did not assert that the Super Cub passed higher than the R44. He advised the ATSB that he “recalled last seeing the Super Cub pass to his left at a lower altitude before his attention was diverted inside the helicopter by the movement of the ammunition container” (see ATSB Final Report p.3);
- The relative bank and pitch between the two aircraft at impact were derived from physical evidence of the contact. The ATSB maintains that the Supercub and the R44 were aligned on a very similar plane at the time of the collision.
Fatigue
The Coroner found that ‘fatigue must have played a significant role’ in both the R44 and Super Cub pilots decision making to allow the aircraft to come into close proximity.
ATSB response
The ATSB reaffirms its finding that:
The R44 pilot’s work schedule was unlikely to have resulted in work-induced fatigue leading to a significant performance decrement in his ability to operate the helicopter.
As part of its investigation the ATSB undertook a fatigue analysis of the R44 pilot. That involved analysing the R44 pilot’s hours worked and his reported rest over the fortnight preceding the accident and on the day of the accident flight. The analysis included examining the pilot’s work and rest periods on the day of the accident using two separate, internationally-accepted bio-mathematical fatigue modelling software programs (FAID and FAST).1
The ATSB was not able to conduct a similar assessment on the Super Cub pilot but it was reported that his workload in the period leading up to the accident was similar to that of the R44 pilot.
Coroner Recommendations:
The Coroner did not make any recommendations directed toward the ATSB; however the ATSB notes the following recommendations by the Coroner:
- That both DEC and DAF put in place guidelines in respect of aerial work which would specifically cover feral animal culling, to ensure that there is at least a 500 foot vertical buffer between spotter and shooter aircraft in addition to any horizontal buffer.
- DEC and DAF take action to ensure that ongoing consideration is given to possible use of available anti-collision systems and particularly the FLARM system.
It is not a matter for the ATSB to provide a response to these recommendations. The ATSB considered that the safety issue arising out of this accident that needed to be addressed was the lack of formalised operating procedures detailing the conduct of multiple aircraft culling operations, including the assurance of aircraft separation that would have assisted the pilots maintain separation from each other.
The ATSB report at pp. 29 to 30 details the actions taken or that were planned to be taken in relation to this issue by the:
- R44 Operator;
- Super Cub Operator;
- WA DEC; and
- DAF WA.
ATSB Investigations and Coronial Inquiries
Inquests are separate to ATSB investigations. The Coroner formulated his findings and recommendations independently of the ATSB. The ATSB cannot speak for the Coroner’s findings. However, the ATSB supports the coronial process and in the interests of ensuring that safety information is made available to the broadest audience the ATSB is making this publication.
The Coroner's report can be obtained from the Coroner's Court of Western Australia. Contact details are available at: www.coronerscourt.wa.gov.au. Queries regarding the Coroner's findings should be directed to the Coroner's Court of Western Australia.
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1 See www.faidsafe.com and www.fatiguescience.com
