What happened
On 24 October 2020, a Singapore Airlines Airbus A350-900, registration 9V-SMU, was preparing for a scheduled flight from Barcelona, Spain, to Milan, Italy. While taxiing toward Runway 07R, the flight crew received instructions from Air Traffic Control (ATC) to "line up and wait." However, after entering the runway, the aircraft began its take-off roll without receiving the necessary take-off clearance.
At the time of the unauthorized departure, another aircraft, an Airbus A320, was on approach to land on Runway 02, which features an approach path that crosses over Runway 07R. The tower controller, who was busy managing a business jet that had just landed, observed the 9V-SMU beginning its take-off roll. The controller determined that the separation between the departing A350 and the approaching A320 was approximately 2.8 nautical miles and decided it was safe to allow the departure to continue rather than aborting the roll. Once the A350 was airborne, the controller notified the crew that they had not been cleared for take-off and were second in the departure sequence.
The investigation
The investigation focused on the crew's situational awareness, the accuracy of radio communications, and the complexities of operating on intersecting runways. Investigators examined the cockpit voice recordings and ground radar data. While the flight crew maintained they believed they had received take-off clearance, ATC recordings confirmed that no such clearance or wind information was ever issued. The investigation also looked into whether the tower controller could have provided more descriptive information to the crew during the initial line-up instruction.
Findings
- The flight crew operated under the mistaken belief that they were the only aircraft in the immediate vicinity, likely due to low aerodrome traffic and low workload, which may have reduced their alertness.
- The crew failed to perform a proper readback of a take-off clearance, and their recollection of receiving such clearance was unsupported by ATC records.
- Although the crew checked the approach path for Runway 07R and found it clear, they did not detect the A320 approaching on the intersecting Runway 02.
- The tower controller's decision to provide the aircraft's position in the sequence (e.g., "number two in the sequence") during the line-up phase could have helped enhance the crew's awareness of other traffic.