Summary
On 25 June 2015, an Airbus A319-111, registration G-EZAA, operated a commercial passenger flight from Belfast Aldergrove Airport. The crew planned a takeoff from Runway 25 using Intersection Bravo. Initial performance figures were calculated for a wet runway, resulting in a full-power thrust setting. Just before pushback, the crew changed the runway condition to dry on the Electronic Flight Bag (EFB), which produced a reduced thrust (flex) setting. During takeoff, the commander realized that a rejected takeoff would not provide sufficient stopping distance and committed to continuing. The aircraft became airborne with approximately 200 m of runway remaining. No injuries or damage occurred.
History of the Flight
The crew consisted of a commander (33, 7,400 hours total, 4,000 on type) and a co-pilot. The co-pilot was Pilot Flying, the commander Pilot Monitoring. Before pushback, the commander entered data into his EFB, including meteorological data from ATIS (wind 160° at 12 kt, visibility >10 km, temperature 17°C, dew point 15°C, QNH 1015 hPa), runway 25 from Intersection Bravo, and flap setting 1+F. He initially selected a wet runway due to nearby showers. Prior to pushback, the crew reviewed the EFB inputs. The co-pilot noted the thrust setting was full power. As the runway was dry, they agreed to see if selecting a dry runway would give a flex takeoff. The commander changed the runway condition from wet to dry and pressed compute. The new figures produced a flex takeoff. The crew input the speeds into the Flight Management and Guidance Computer (FMGC) and performed a gross error check on green dot speed and engine-out acceleration altitude but did not independently review all EFB entries.
The aircraft pushed back and taxied to Intersection Bravo. The runway end is not visible from the start due to a hump. At about 115 kt, the commander saw the runway end. He believed that at the calculated V1 of 130 kt, there would be insufficient stopping distance, so he became committed to the takeoff. He continued monitoring, satisfied that the aircraft could accelerate and rotate within the remaining runway. He decided to maintain flex thrust to avoid distracting the co-pilot. He called rotate approximately 600–700 m before the runway end, and the aircraft became airborne about 200 m from the end. The departure was uneventful.
Takeoff Performance
After departure, the commander discovered that Runway 07 was displayed in the EFB runway field instead of Runway 25B. The incorrect runway had been used for the dry performance calculation. The crew recalled the takeoff mass was 58.6 tonnes and the dry performance figures for 25B were V1 130 kt, VR 135 kt, V2 139 kt with a flex temperature of 67°C. Post-event calculations by the manufacturer showed that for a dry Runway 07, the correct figures were V1 135 kt, VR 135 kt, V2 139 kt with flex 67°C. For the correct dry 25B, the figures were V1 118 kt, VR 125 kt, V2 131 kt with flex 49°C. For wet 25B, the figures were V1 112 kt, VR 124 kt, V2 131 kt with TOGA thrust.
EFB Anomaly
The reason for the incorrect runway selection could not be confirmed. However, subsequent investigations revealed that in one scenario, an involuntary runway change could occur on the EFB. This anomaly was not known by the operator or manufacturer at the time of the event and is likely to have been the reason for the incorrect runway selection.
Operator Procedures
The operator's Operations Manual Part B provided guidance for takeoff data computation and cross-checking. The operator introduced EFBs in 2003. The aircraft manufacturer's recommended SOPs required each crew member to perform an independent calculation, but the operator considered their own SOPs more appropriate for their operational requirements.