Description

On 6 September 2019, a Boeing 737-800 (PH-HSJ) being operated by KLM subsidiary Transavia on a scheduled international passenger flight from Amsterdam to Chania and cleared to takeoff from runway 18C in normal night visibility actually began doing so on the parallel taxiway and did not commence what was a high speed rejected take off until told to by the controller. The crew then decided they should try again and this subsequent takeoff as cleared was normal. 

Investigation

A Serious Incident Investigation was carried out by the Dutch Safety Board (DSB). The FDR was not downloaded but relevant data from the QAR was read out and “made available to the Investigation” in an unspecified format. To the extreme concern of the Board, the fact that the crew had then made a runway takeoff and completed the flight meant that relevant CVR data had been overwritten and important evidence as to how the inattention of the crew had culminated in a taxiway takeoff attempt had thereby been lost. In this respect, it was noted that the applicable regulations required that:

• In the event of a serious incident, the Captain is responsible for deactivating the flight recorders immediately after the flight is completed.  
• The aircraft operator should establish procedures to ensure that flight recorder recordings are preserved for the investigating authority. The procedures should include instructions for flight crew members to deactivate the flight recorders immediately after completion of the flight and inform relevant personnel that the recording of the flight recorders should be preserved. These instructions should be readily available on board.

Whether a rejected takeoff which is not then immediately followed by a successful one is still a single ‘flight’ for the purposes these regulations is unclear.

The Transavia OM Part ‘A’ was found to state as guidance that “flight crew (must) not erase the CVR after an incident/accident (but must) inhibit it immediately to avoid erasure and only stop (it) in flight when deemed necessary to secure data”. As with the regulations above, this text does not provide useful clarity in the case where a rejected takeoff is followed immediately by a successful one. 

The Flight Crew

It was noted that the fight crew pairing was the standard Captain and First Officer who were both “fully qualified to fly the Boeing 737-800”, contrary to the Board’s previously longstanding practice, no information was given as to the age and experience of the pilots involved. However, it was noted that the Captain had been operating from the airport for almost 20 years and the First Officer for about three years which meant that “they were both familiar with the infrastructure of the airport”.

The Air Traffic Controllers

The aerodrome controllers on duty were the TWR controller and the GND controller with the TWR controller designated as the Supervisor and covering departures from runway 18C and landings on runway 18R. He had decided to use taxiway W5 to get traffic which had landed on runway 18R across departure runway 18C before continuing on taxiway ‘D’ to avoid a longer route to the terminal.

What Happened

The flight was instructed to taxi for a runway 18C departure in normal night visibility via taxiway ‘C’ (see the illustration below). The flight, with the First Officer acting as PF, had been given a slot but was ready to taxi in good time and the crew were "not in a rush”. The aircraft entered taxiway ‘C’ with no aircraft ahead of it and taxied north. As it passed abeam taxiway W4 the GND controller instructed it to contact TWR and on doing so when the aircraft was near taxiway ‘C2’, the Captain advised that the flight was ready for departure and the controller responded by issuing a clearance to line up on runway 18C and take off.

The ground track of the aircraft prior and during the attempted taxiway takeoff. [Reproduced from the Official Report]

The aircraft turned left onto taxiway ‘W1’ and then left onto taxiway ‘D’ and immediately commenced takeoff. The Captain made the 80 knot call and having been alerted by the GND controller, the TWR controller immediately looked at his ground radar display, saw what was happening and “instructed the flight twice to stop immediately and hold position”. At the time this instruction was given, the aircraft was between W2 and W3. The captain took over control and rejected the takeoff with the aircraft coming to a stop just beyond taxiway ‘W5’. Only after being informed that they had been attempting to take off from a taxiway did the pilots realise what they had done. The cabin crew and the passengers were told that the takeoff had been rejected due to a flight deck warning.

The controller asked if attendance of the RFFS was required in the event of excessive brake temperature or any other reason and the Captain replied that this was unnecessary. The pilots stated that having discussed what had happened, they had “judged that they were able to continue the flight” and advised the controller that they wanted to try again and were instructed to “take the first opportunity to turn and return to ‘W1’". The flight subsequently took off normally from runway 18C. The Captain was recorded as saying that he had tried unsuccessfully to “contact Transavia” but how he had done so, whom he had attempted to contact and what he had intended to say were not recorded.

It was noted that no part of the airport has controllable taxiway centreline lighting. It was additionally found that taxiway centreline marking in the area where the crew turned onto the taxiway they erroneously believed was the runway was normal bar two intentional 11 metre long breaks in the ‘C1’ taxiway centreline (see the illustration below). One break was at the beginning of the route from parallel taxiway ‘C’ to taxiway ‘C1’ and the other was where a left turn onto taxiway ‘D’ diverged from the principal ‘C1’ straight ahead route towards taxiway W1 and the runway. The Captain’s claim that the centreline lighting between taxiway ‘C’ and the Cat 3 holding point on taxiway W1 was not illuminated could not be validated as there was no system which displayed such failures. However ATC had not received any corresponding failure from the 7 earlier departures from runway 18C which had all followed the same access to the runway. 

The short (11 metre) breaks in the taxiway ‘C1’ centreline leading to taxiway ‘W1’ and the runway. [Reproduced from the Official Report]

The Investigation noted that the Board had investigated a previous parallel taxiway night takeoff at Amsterdam which occurred in 2010 which also involved a locally based (KLM) flight crew familiar with the airport, in that case resulting in the aircraft completing the takeoff without any problems.  

Why It Happened

It was considered that although the airport infrastructure and system of operational control was complex, the taxi route followed in this case “cannot be described as complex”. However it was noted that “use of a runway and a parallel outer taxiway for departing traffic from that runway involves the risk, although small, of assuming the inner taxiway is the runway”. 

It was broadly concluded that the “environmental cues enhanced the perception of the crew that they were lined up on Runway 18C, instead of on Taxiway D” which represented a confirmation bias. It was also clear that “cues such as the yellow, thin and continuous centre line marking and green centre line lights, were not recognised by the flight crew as cues of being on a taxiway”. 

The break in the centreline introduced on taxiway C1 near to its junction with taxiway ‘D’ was considered likely to have been a significant factor in the suspected confirmation bias mechanism. It was noted that  both the non-standard taxiway centreline breaks on taxiway C1 had been introduced as part of a wider scheme to reduce the risk of runway incursions during low visibility by having some centrelines leading to another taxiway instead of to a runway. It was noted that this deviation from the applicable regulated multinational aerodrome standards had been identified as non-compliant and a justification for this to the agency concerned has not yet been accepted.

A wider reason why the event had occurred was identified as a failure to act on previous relevant DSB Safety Recommendations made after the 2010 event following which a 2012 Risk Assessment “did not provide clear guidance on how to mitigate the risk of taxiway takeoffs (and) a clear, structured and integral follow-up of the outcomes of this

report did not take place”. It was found that “over time focus and resources shifted to the risks involved in pushback operations (and) the commitment to act upon the risk of taxiway takeoffs was neither followed nor challenged”. It was observed that as a result, actions which could have followed the investigation of the 2010 event “were not developed further and therefore could not help prevent reoccurrence of taxiway takeoffs”.

Three specific Contributory Factors were identified in respect of this Serious Incident as follows:

• The use of outer Taxiway C in combination with an early issuance of the takeoff clearance, introduced a risk of taxiing incorrectly.
• The TWR controller issued the takeoff clearance when prompted by the crew with a ready for departure notification. Thereafter he shifted his attention to other traffic and did not observe the line-up of the aeroplane on Taxiway D. Based upon the operational situation and his expert judgement, the runway controller did not perceive his reduced focus on the Boeing 737-800 as a risk, especially because it concerned a home-based carrier.
• When taxiing from Taxiway C towards the holding position of Runway 18C, the taxiway centre line markings did not provide continuous guidance, as the design of these markings was focused on preventing runway incursions during low visibility operations.

Safety Action taken as a result of an internal review by interested airport parties which followed this event resulted in designation of taxiway ‘D’ as the standard routing for traffic departing runway 18C at night and restoring the previously removed section of taxiway centre line marking between taxiway ‘C’ and runway 18C.  

Five Safety Recommendations were made as a result of the findings of the Investigation as follows:

• that Transavia develop new procedures, or clarify existing procedures, that guide flight crews to consult with their airline at the earliest convenient moment, about abnormal situations that have had or may have significant flight safety implications, such as an aborted takeoff from a taxiway. Communicate to flight crews what range of occurrences are meant by these situations.
• that All Dutch Airlines replace or upgrade existing cockpit voice recorders currently in use to accommodate for a storage capacity of at least 25 hours on aeroplanes with a certified maximum takeoff mass of more than 27,000 kg and with a certificate of airworthiness issued after 31 December 2001, before 2028.
• that the International Air Transport Association encourage their members to replace or upgrade their existing cockpit voice recorders currently in use to accommodate for a storage capacity of at least 25 hours on aeroplanes with a certified maximum takeoff mass of more than 27,000 kg and with a certificate of airworthiness issued after 31 December 2001.
• that the European Union Aviation Safety Agency mandate that EU-registered commercial air transport aeroplanes, with a certified maximum certificated takeoff mass of more than 27,000 kg, and with a certificate of airworthiness issued after 31 December 2001, to be equipped with a cockpit voice recorder capable of retaining recorded data for at least 25 hours; implement this requirement as of 1 January 2028.
• that the Integral Safety Management System Schiphol foster a work environment at Amsterdam Airport Schiphol that encourages the stakeholders of the Integral Safety Management System to challenge each other about decisions that have had or may have significant safety implications.

The Final Report was published on 25 May 2022.

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• Inappropriate Use of Taxiway
• Runway Excursion
• Safety Management
• Safety Management System
• Taxiway Surface Markings