Description

On 24 October 2020, an Airbus A350-900 (9V-SMU) being operated by Singapore Airlines on a scheduled international passenger flight from Barcelona to Milan Malpensa took off without clearance from runway 07R in day VMC and lateral separation with an Airbus A320 on approach to runway 02 - which involves a low level overflight of runway 07R - was reduced to 2.8 nm. 

Investigation

An Investigation was carried out by the Singapore Transport Safety Investigation Bureau (TSIB). On arrival at Milan, the 2 hour CVR was removed and downloaded but all relevant data was found to have been overwritten. Relevant ATC data was made available.

The 49 year-old Captain had a total of 9,807 hours flying experience which included 313 hours on type and the 41 year old Senior First Officer, who was acting as PF for the sector involved had a total of 5,066 hours flying experience which included 251 hours on type. During the preceding 90 days, they had respectively recorded 97 and 140 flying hours. One of the two flight deck supernumerary crew seats was occupied by a 48 year-old Senior First Officer who was one of the crew who were rostered to operate the next sector of the flight, from Milan to Singapore, who had a total of 11,699 hours flying experience which included 1,750 hours on type and had recorded 94 flying hours during the preceding 90 days. Neither he nor the Captain he would later be operating with, who was not on the flight deck, had any assigned role on the Barcelona - Milan sector.     

What Happened

It was established that Barcelona was being operated with runway 07R used for departures and runway 02 for landings - see the illustration below. On completion of pushback, the departing flight was instructed to taxi to the runway 07R full length holding point via parallel taxiway ‘K’. The airport was very quiet at this time (mid morning) and the crew did not see any other aircraft on the ground whilst taxiing as instructed and airport surface movement radar recordings confirmed that the A350 was the only aircraft departing. At this time, the TWR controller was talking to an Airbus A320 on approach to runway 02 behind a business jet on the same approach, but had completed this exchange whilst the A350 was still on the GND frequency. 

The runway layout at Barcelona with the A350 taxi route to runway 07R shown. [Reproduced from the Official Report] 

Whilst taxiing along taxiway ‘K’ the GND controller transferred the flight to TWR and on checking in there, the controller asked if they were ready for departure and the crew confirmed that they were. The TWR controller responded by instructing the flight to “line up and wait” which was read back correctly. After this the controller began issuing initial taxi instructions to a business jet which had just landed on Runway 02 on the single TWR frequency in use. At that point, his plan was to land the A320 which was on approach to runway 02 and then issue take-off clearance to the A350.

The A350 First Officer stated that as the aircraft passed the holding point i.e. was now at 90° to the runway 07R approach path and was about to enter the runway, he had routinely checked his ND, which was set to a 10nm range and would have provided a view of all traffic within +/- 90° of the aircraft within that range limit, and had seen no traffic on or near the approach to runway 07R. The runway 02 approach was not mentioned. 

Whilst the TWR controller was still speaking to the business jet, he reported seeing the A350 begin a takeoff roll on Runway 07R. Having assessed that there was sufficient separation between it and the approaching A320 as their ground tracks had already crossed, he stated that he had decided that it was safe to allow the A350 to continue taking off and therefore unnecessary to instruct it to reject its takeoff. He subsequently called the A350 after it had become airborne to advise the crew of their failure to comply with their clearance. The rest of the A350 flight to Milan was recorded as having been without further event. 

Discussion

The A350 crew “recalled having received a takeoff clearance” but this was on the clear evidence available not the case. It was considered that the takeoff without clearance would have been less likely to occur if the TWR controller had mentioned the existence of a second (A320) aircraft on approach to runway 02 although of course there was no requirement to do this.

The formally stated Conclusions of the Investigation were as follows: 

• The flight crew had believed that they were the only aircraft traffic in the vicinity. The low workload in traffic monitoring due to the low aerodrome traffic could have resulted in some form of reduced alertness by the flight crew. 
• The flight crew claimed that they heard a take-off clearance when there had not been one. There was no readback of take-off clearance by the flight crew. 
• The flight crew had checked the approach path of Runway 07R and found it to be clear. The PF mentioned checking the surrounding vicinity for approaching aircraft traffic but did not detect the A320 that was approaching Runway 02.  
• Although the TWR controller had managed the take-off situation appropriately, it would be desirable if the flight crew could have been made aware of other aircraft traffic in the vicinity. The TWR controller could have assisted by providing additional information (when issuing the line-up clearance) to the flight crew of the departing aircraft (such as stating the order of the aircraft in the queue with respect to other aircraft traffic), so as to enhance the awareness of the flight crew to the presence of other aircraft.

Safety Action taken by Singapore Airlines as a result of the event during and known to the Investigation was noted as having included the following:

• issued an INTAM (Internal Notice to Airmen) immediately after the incident for all flights operating to or from Barcelona Airport to require the flight crew to adhere to proper radio communication and readback procedures. The INTAM also reminds the flight crew that ATC instructions should be verified and cross-checked amongst themselves and that any doubt should be clarified with the ATC. The information in the INTAM was also incorporated into the Barcelona Airport Briefing given to flight crew.
• shared details of the incident with its pilots via a ‘Preliminary Factual Bulletin' which also provided an overview of some common human factor elements that any flight crew should be aware of. 
• enhanced its existing ‘Additional Crew Support Tool’ with a pictorial quick reference version. This Tool provides guidance on how additional crew members in the flight deck (e.g. an observer crew member) can support the flight crew during certain phases of the flight and is available on the PEDs that the airline issues to its flight crew. 
• issued a reminder to all its pilots reiterating the importance of securing the flight recorders in a timely manner after an incident.

One Safety Recommendation was made as a result of the Investigation as follows: 

• that the Barcelona ANSP consider, when available, offering additional information to departure and arrival aircraft so as to enhance the awareness of the flight crew to the presence of other aircraft (e.g. the order of an aircraft in the queue with respect to other aircraft traffic). [RA-2021-011]

The Final Report was published on 6 September 2021.

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