Air France A319 at Sofia on Oct 16th 2012, rejected takeoff from taxiway
Last Update: November 27, 2014 / 15:42:48 GMT/Zulu time
Crew error while taxiing leading to exiting assigned taxi route onto taxiway H and subsequent take off attempt from taxiway H.
Incomplete pre-flight preparation for flight AFR-1587 by the crew, reduced attention by the crew while taxiing and lack of situational awareness, tracking of own position around the maneouvering areas of the aerodrome, by the captain of the flight.
Inadequate monitoring of aircraft movement by tower air traffic control.
The BAAIU reported that the first officer (44, ATPL, 8,242 hours total, 1,748 hours on type) was pilot flying, the captain (48, ATPL, 12,644 hours total, 511 hours on type 464 hours thereof in command) was pilot monitoring. The crew had overnighted in Sofia after arriving the previous day at about 11:00Z and arrived at the aerodrome at about 03:00Z (06:00L).
The captain reported in post occurrence interviews, that he was impressed by the landscape and had noticed the possibility of confusing taxiway H and the runway upon arrival.
Following pre-flight preparation including a briefing which mainly focussed on the possibility of bird strikes, the possibility of an engine failure past V1, the surrounding terrain and the related procedures related to heights on single engine operation, however, the observation of the captain of the previous day, the possibility of confusing taxiway H (which in fact used to be the main runway of Sofia in the past) and runway was not mentioned during the briefing.
At about 03:36Z the crew requested clearances for push back and engine start, tower reports their slot time was 04:10Z. Push back clearance is thus issued at 03:45Z. At 03:51Z the crew reported ready for taxi and got assigned taxi route N, left onto J, then B, hold short of runway 09, the crew acknowledged the taxi instructions correctly.
While taxiing the crew executed the checklists for departure. The airline had issued completely new normal checklists to be in effect the following day, as both pilots already had the new checklists available the crew decided to use the new checklists already for their departure. The commander later provided testimony that they were taxiing at low speed to give them time to work with the new checklists.
AF-1587 was the first flight to operate in Sofia that day, tower therefore issued the clearance to line up and when ready take off runway 09 while the aircraft was still taxiing at 03:55Z. The crew acknowledged the clearances, reported ready for departure at 03:57Z, tower re-issued clearance for takeoff. Instead of continuing straight on taxiway B towards runway 09 the crew turned right onto taxiway H, stopped for about 16 seconds, then began to accelerate for takeoff.
The tower controller reported in post occurrence interviews that he first noticed the lights of the aircraft in a closer position than runway 09, checked with the ground radar and confirmed that the aircraft was indeed accelerating on taxiway H. At 03:58Z tower issued several instructions to stop, the crew rejected takeoff at low speed (37 knots over ground) and slowed safely, received instructions to turn right onto taxiway C, later instructing the aircraft to turn right onto J and B.
After a stop to work checklists tower decided to change the taxi instructions and amended the taxi instructions to turn left onto taxiway H (where the crew had turned right at first attempt) and right onto taxiway A. The aircraft departed runway 09 at 04:14Z.
The BAAIU reported that visibility improved gradually between 03:00Z and 04:00Z reaching about 4000 meters of visibility and concluded that the weather had no effect limiting needed visibility during taxi.
The BAAIU analysed that it was the first flight of the captain to Sofia, the first officer however had been to Sofia several times before.
The BAAIU analysed that the captain had used the new checklist cards about 4 to 5 times already in simulator training, the first officer however had not had that opportunity. Given that the flight was in the early morning hours with no rush and the delay in slot time the captain decided to use the new cards. According to testimony of the first officer he encountered problems in implementing the "Before Departure" checklist however, which tied his attention mainly onto the cards. It is probable that the takeoff clearance in the midst of these difficulties increased the work load even further as it invoked the use of the next "Takeoff" checklist consisting of three points.
The BAAIU analysed that the captain's decision to use the new checklists, which were not yet in force, was incorrect. Further deficiencies in crew cooperation, distribution of crew tasks and crew training, in particular with the new checklist cards, contributed to the crew attention being diverted from monitoring taxi and determining their position correctly.
The BAAIU analysed that the presence of yellow (taxi) lines, absence of white (center and edge) lines, green taxi center line lights along the axis of taxiway H, blue edge lights as well as the crew not crossing the hold short line should have alerted the crew to detect they were not on the runway. "This indirectly confirms that the crew has been extremely busy with the implementation of the checklist 'Before Departure' and their attention was largely concentrated on it", the BAAIU wrote. The BAAIU assessed that the markings and lightings at the aerodrome did not contribute to the serious incident.
With the unexpected clearance to takeoff while still taxiing and still focussing on the implementation of the "Before Departure" checklist the workload increased causing the crew to turn right prematurely onto taxiway H. The captain stated in post occurrence interviews that he had no doubts about their position being on runway 09. However, the BAAIU analysed, the aircraft stopped for about 16 seconds, time enough for both pilots to recognize they were not on a runway and states even stronger: "Evidence suggests that the captain has not taken any action to establish their position around the movement area."
The BAAIU further analysed that the aircraft was equipped with EGPWS and RAAS systems which would have sounded "approaching runway 09" and "on runway 09" as the aircraft would have taxied onto and lined up the runway. Neither sounds occurred, the absence of the announcements was not noticed by captain or first officer, the BAAIU states: "This could be explained by the work load reading the new checklists "Before Takeoff".
The BAAIU analysed that the EGPWS and RAAS systems would have sounded an automatic warning "On Taxiway! On Taxiway!" as soon as the aircraft had accelerated to or above 40 knots. As takeoff was rejected at 37 knots the warning was not issued.
The BAAIU analysed that it was the first officer who retarded the power levers and rejected takeoff concluding that the captain's hand was NOT on the power levers although required by the standard operating procedures, as it is the commander who ultimately decides whether takeoff is being rejected or continued. The related checklist contains this requirement, the commander having his hand on the thrust levers, in bold. The BAAIU analysed that this is manifestation of passitivity of the commander with respect to crew task distribution, verifying aircraft position on the aerodrome and decision to reject takeoff, which effectively was done by the first officer.
The BAAIU analysed that the captain had relatively little experience on the A320 (511 hours total, 464 in command) while the first officer was experienced in comparison. In addition, it had been the captain's first flight to Sofia while the first officer had been to Sofia a number of times. This may have contributed to the passitivity of the captain and the omission of the captain's observations (terrain, possible confusion of taxiway H and runway) during the departure briefing.
The BAAIU analysed that the tower controller's shift was to end at 04:00Z with a new controller coming in. The early takeoff clearance, with no other traffic around yet, would have permitted the controller to focus on the push back and taxi of pending next three departures. The manual for Sofia tower does not define when a takeoff clearance can be issued while the aircraft is still taxiing, it was common practise however to issue takeoff clearance during taxi to reduce runway occupancy times.
The BAAIU analysed that it was obligation by tower to monitor the movements of aircraft on the aerodrome. Tower did not recognize the aircraft lined up on the taxiway H as he was busy with the next departures. Only when the controller noticed the aircraft lights moving in an unusual position - the blue taxiway edge lights and green taxiway center line lights were not visible to the tower due to being directional along the axis of the taxiway - he cross checked with the ground radar, confirmed the aircraft was accelerating on taxiway H and instructed the aircraft to reject takeoff with the crew rejecting takeoff at 37 knots. The BAAIU assessed that this action was adequate and timely. The BAAIU analysed however that this action depended on the visual observation of movement on the aerodrome, the ability to cross check with ground radar, work load, controller experience, momentary phsyical and mental state and concentration of the tower controller. In this particular case the tower noticed the movement visually, his experience permitted to identify the movement as unusual, his work load coordinating 4 aircraft in the maneouvering area permitted cross check with ground radar and thus permitted the prompt reaction to prevent takeoff from a taxiway which may have resulted in an accident.
This article is published under license from Avherald.com. © of text by Avherald.com.
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