Created Thursday, Dec 16th 2021 16:53Z, last updated Thursday, Dec 16th 2021 16:53Z
A REX Regional Express Saab 340B, registration VH-ZRH performing flight
ZL-2269 from Carnarvon,WA to Perth,WA (Australia) with 30 passengers and 3 crew, was taxiing for departure from runway 22 when the aircraft entered the runway to backtrack the runway.
A private Piper PA-31 was just in the takeoff roll from runway 22 and rejected takeoff due to the Saab entering the runway ahead of them.
The ATSB rated the occurrence an incident and opened a short investigation.
Both aircraft subsequently departed from Carnarvon's runway 22.
Carnarvon Airport does not feature a parallel taxiway to the runway, to reach the threshold runway 22 for departure the aircraft need to backtrack the runway entering the runway near the runway 22 end.
On Dec 15th 2021 the ATSB released their final report concluding the probable causes of the incident were:
Contributing factors
- The flight crew of VH-ZRH were not aware, as they entered the runway, that VH-ITF had commenced its take-off roll. As a result, a potential conflict existed that required the pilot in command of VH-ITF to reject their take-off.
- The lookout conducted by the flight crew of VH-ZRH before entering the runway was not effective in identifying VH-ITF on the runway threshold. This was likely influenced by the crew’s expectation that VH-ITF had already departed.
- Although both flight crews were aware that they were mutual traffic, they both had an incorrect understanding of the other’s position and/or intentions, which led to them not recognising the potential conflict and therefore not directly communicating with each other.
The ATSB analysed:
In this incident, the crews of both aircraft were provided with sufficient information to aid their situational awareness and be alerted to traffic relevant to them. However, the pilots did not fully comprehend the traffic picture and/or did not recognise the potential conflict that existed.
Although the flight crew of VH-ZRH believed VH-ITF to have departed, the traffic information provided to them by Melbourne centre clearly stated that VH-ITF was still taxiing at Carnarvon.
Although it is possible that a controller could provide such information in cases where an aircraft had departed and the crew had not yet made a departure call, the statement that VH-ITF was taxiing (and was therefore a potential conflict) should have been assumed to be true until the crew could confirm otherwise.
Expectations strongly influence where a person will search for information and what they will search for (Wickens and McCarley 2008), and they also influence the perception of information (Wickens and others 2013). In simple terms, people are more likely to see or hear what they expect to see or hear, and less likely to see or hear things they do not expect. Expectations are more likely to have an influence when some of the available cues are not salient. In this case, the flight crew had developed an expectation that VH-ITF had already departed, and it is likely that this expectation then strongly influenced their perception of subsequent information.
In particular, this expectation bias likely influenced the flight crew’s ability to visually scan for traffic prior to entering the runway. As they were not expecting traffic to be there, the captain looked but did not see VH-ITF on the threshold. The ATSB notes that although the background potentially masked VH-ITF from the captain’s scan, the ARO was able to see VH-ITF from a similar position.
The pilot of VH-ITF was fully aware that VH-ZRH was taxiing and, having heard all of that crew’s transmissions, assumed they were equally aware of VH-ITF. The pilot expected VH-ZRH would hold short and, therefore, a potential conflict did not exist. Consequently, the pilot did not believe there was a need for direct radio contact with the other crew to clarify their intentions.
As the pilot of VH-ITF had VH-ZRH visual, they were able to quickly reject the take-off when VH-ZRH entered the runway.
