What happened
On 16 September 2019, an Airbus A320-214, registration G-EZWE, was preparing for a commercial passenger flight from Lisbon Airport to Manchester. During the pre-flight phase, the flight crew was subjected to several interruptions, including changes to fuel requirements and passenger loading figures. While calculating takeoff performance, the crew intended to select the intersection for Taxiway S1, but they inadvertently selected the data for the full length of Runway 2 1.
The aircraft subsequently taxied to the holding point at Taxiway U5 and commenced its takeoff roll. Because the performance had been calculated for a much longer runway, the aircraft lacked the necessary thrust margin for its actual departure point. As the aircraft accelerated, the crew noticed the red and white runway end lights approaching rapidly. The aircraft became airborne with only 110 m of runway remaining. There were no fatalities and no injuries to the 167 passengers or 6 crew members on board.
The investigation
The AAIB investigation established that the crew used the incorrect takeoff point in the Electronic Flight Bag (EFB) software. The crew believed they were using the shortest available runway length, but the selection actually corresponded to the full runway length. This error was not detected during the initial calculation or the subsequent pre-takeoff cross-checks.
Investigators found that the nomenclature used in the EFB software was confusing, as it did not use standard taxiway names. Furthermore, the commander's EFB was difficult to use because the mounting cradle was broken, and the device's battery life was significantly degraded. The investigation also noted that the aircraft's takeoff distance available from U5 was 1,395 m less than the distance used in the performance calculation.
Findings
- The crew selected the incorrect takeoff intersection in the performance software, believing it represented Taxiway S1 when it actually represented the full runway length.
- Frequent interruptions during the pre-flight preparation phase contributed to the calculation error.
- The EFB software nomenclature for Lisbon Airport was ambiguous, leading to confusion between different runway positions.
- The aircraft's takeoff performance was calculated for a runway length significantly greater than the distance actually available from Taxiway U5.
- The crew failed to identify the error during the required cross-check of the EFB data against the aerodrome ground charts.
Safety action
- The airport operator renamed several taxiways to ensure that Taxiway S only intersects Runway 21 at a single point, reducing confusion.
- The aircraft operator transitioned to a newer version of performance software that provides a pictorial representation of the selected takeoff point.
- The EFB selection menu was updated to eliminate the use of 'Position S' to clarify that it refers to the full runway length.
- The UK CAA revised its EFB compliance checklist to emphasize the necessity of a periodic battery replacement programme for flight tablets.