British Airways A321 at Glasgow on Nov 24th 2019, incorrect takeoff performance
Last Update: May 14, 2020 / 15:51:34 GMT/Zulu time
The AAIB released their bulletin concluding the probable cause of the serious incident was:
The investigation found the incorrect entry was probably a result of distraction during the data entry. The subsequent standard procedures and checks did not detect the error.
The AAIB described the sequence of events:
During passenger boarding the flight crew had a few minutes spare, so, as encouraged by the operator, the commander allowed a couple of passengers to visit the flight deck.
Later, whilst the flight crew were entering the takeoff performance figures into the FMGC the senior cabin crew member asked if they could accept another flight deck visitor. The commander ignored the request and focused on the data entry but, he reported, it may have distracted him.
The takeoff was planned from the full length of Runway 05. The surface wind was from 080° at 5 kt, the visibility was 2,800 m in drizzle with cloud broken at 400 ft. The temperature was 8°C and the runway surface was wet. The takeoff performance calculation required flap 1, a flex temperature of 49°C, a non-standard acceleration altitude of 1,070 ft and takeoff speeds of V1 139 kt, VR 147 kt and V2 151 kt.
The flight crew completed the flight deck preparations and the aircraft was pushed back from the stand on time at 1803 hrs. At 1808 hrs the flight crew received their final load sheet which was consistent with the provisional figures. During taxi air traffic control asked if they could depart from Intersection F as another aircraft was holding at Taxiway G with a technical problem. However, before the flight crew changed the performance figures the crew of the other aircraft resolved their problem and it was able to depart.
G-EUXJ continued to the full length of the runway and the flight crew completed the before takeoff checklist. As they started the takeoff roll, their standard review of the Flight Mode Annunciators (FMA) was interrupted by several radio transmissions.
During the takeoff roll both pilots reported that they felt something was wrong, they felt the aircraft was not accelerating as they expected. The commander reported that “something was not right but I could not put my finger on it”. At approximately 100 kt the co-pilot verbalised “this does not feel right, have we got enough power”. At 137 kt the commander advanced the thrust levers to TOGA power. The co-pilot recalled the aircraft had entered the last 900 m of the runway when the aircraft rotated. Subsequent flight data showed that the aircraft crossed the upwind end of the runway at 276 ft. The aircraft continued to Heathrow without further incident.
After takeoff, the flight crew realised they had entered a flex temperature of 79°C instead of 49°C.
The AAIB analysed:
The flight crew inadvertently entered a flex temperature of 79° instead of 49°. The error was not detected during the subsequent procedures and checks.
The error was likely made due to a combination of brief distraction and entering a non‑standard acceleration height. The subsequent checks do not require the flight crew to refer back to the source data and, whilst the selected flex temperature was unusual for a A321, it was not usual for the A319 which the flight crew had been operating during the tour.
The flight crew realised there was insufficient power during the takeoff roll and applied TOGA power.
The operator has reminded its pilots about the hazard of distraction during critical data loading and are reviewing their procedures to improve the likelihood that data entry errors are detected.
This article is published under license from Avherald.com. © of text by Avherald.com.
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