Diverted Attention
The starter extension included a taxi guideline that curved toward the extended centerline. Flight data showed the aircraft followed the guideline from the starter extension bypass pad until the right turn to line up on runway 09. The captain reported that, although their intention was to use the full length of the extension, it was not required. Due to dark ambient conditions, they did not want to risk exiting the pavement and turned the aircraft early.
The flight crew reported conducting ready checks while turning to line up for departure. The Flight Crew Operating Manual stated that ready checks could be conducted at a time appropriate for the anticipated take-off but provided no specific guidance, leaving the decision to crew discretion. The first officer and captain had predominantly focused their attention inside the flight deck while conducting the ready checks. The captain also reported becoming momentarily distracted looking out the side window at a time when they would also be required to monitor the aircraft's taxi path. Data showed the aircraft turned tightly to the right of the extended centerline and no longer followed the line markings for guidance.
Research by Barshi and others (2009) discusses that attention can become absorbed in one or more tasks, allowing another task to drop from awareness. It was concluded that during the turn to line up, the flight crew's attention was diverted to completing the ready checks, likely reducing their monitoring of the aircraft's position within the starter extension, resulting in it being close to the edge of runway 09. This was consistent with an ATSB research report (2010), which discussed flight crews becoming focused on other tasks upon entering or just prior to entering the runway, frequently cited in misaligned take-off occurrences.
Misaligned Take-Off
Although not required for performance, using the starter extension allowed for additional take-off distance and a wider turn than typically available. However, as identified through ATSB research (2010) and related investigations, additional pavement on one or both sides of the runway has provided erroneous visual cues for pilots, potentially giving the impression that the additional pavement is part of the runway and that the runway is wider than it is.
Following completion of the ready checks and when the aircraft neared completion of the turn to line up, the captain reported being drawn to a row of white lights, believing them to be centerline lights, even though such lights were not fitted to runway 09. With reduced visual cues due to dark conditions, a distinct visual indicator such as the white runway edge lights likely influenced their belief that it was the runway centerline. Such dark ambient conditions have been consistently cited in research and similar occurrences. The first officer reported looking up but also believed the aircraft was correctly lined up, associating their observation of the runway threshold markings as being in the correct position.
Imagery of runway 09 in similar conditions showed that the runway threshold lights, edge lights, and right side precision approach path indicator lights would have been visible to the crew from their lineup position. Confirmation bias is the tendency to seek information and cues that confirm a tentatively held hypothesis or belief (Wickens et al, 2022). As the flight crew believed they were correctly aligned with the runway centerline, they commenced the take-off roll.
Low Pass
The flight crew noted no indications of a landing gear malfunction or failure, and the gear was retracted without issue following the misaligned take-off. They received advice from the Mildura Airport aerodrome reporting officer that no aircraft parts or debris were identified along the runway. As the aircraft documentation did not provide guidance for such an incident, and to further assess the condition of the landing gear, the flight crew decided that a visual inspection via a low pass of the Melbourne Airport ATC tower was necessary. The flight crew did not contact QantasLink operations for assistance regarding the landing gear or the conduct of the low pass. This prevented QantasLink from providing input into the decision-making process. While a visual inspection (using binoculars) by ATC from the tower may give a general assessment of the landing gear, it was not likely to have identified specific issues.