26 July, 2020

Even the smallest of distractions can have serious consequences..................investigation report

British Airways Airbus A321-231 G-EUXJ  Photo  Anna Zvereva 
A British Airways flight crew were starting the fourth day of a four-day short-haul period of duty on 24th November 2019 in the early evening.   On this day they were just scheduled to fly an Airbus A321-231 down from Glasgow Airport to the airlines home base of London Heathrow. 

In the previous three days of this four-day rotation, they had flown a variety of aircraft - A319, A320 and A321 and hadn't reported anything out of the ordinary. This day they were flying a 2007 A321-231, registration G-EUXJ for the short flight down to London.  During passenger boarding, the flight crew had a few minutes spare, so, as encouraged by British Airways, the 57-year-old commander allowed a couple of passengers to visit the flight deck. A Little later, whilst the flight crew were entering the takeoff performance figures into the Flight Management and Guidance Computer the senior cabin crew member asked if they could accept another flight deck visitor. The commander ignored the request to continue to focus on putting in the information to the FMGC, a distraction nonetheless. 

The crew planned to take off from runway 05 at Glasgow, which was wet at the time and there was a light drizzle on the air with broken cloud at about 400 feet. The outside temperature was 8°C and the window was light at around 5 knots.  A take-off performance calculation required flap 1, a flex temperature of 49°C (reduced thrust), a non-standard acceleration altitude of 1,070 ft and take-off speeds of V1 139 kt, VR 147 kt and V2 151 kt.

The crew completed the rest of their checks and preparations and following a relatively short taxi to toward the runway, the controller in the tower asked if they could depart from Intersection F as another aircraft was holding at taxiway G with a technical issue. Although before the British Airways crew altered the information in the FMGC, the other aircraft resolved their issue and was able to depart.

The crew then travelled to the full length of the runway and did the pre-take-off checks and started to roll down the runway. During the takeoff roll, both pilots reported that they felt something was wrong, they felt the aircraft was not accelerating as they expected. 

“something was not right but I could not put my finger on it” the commander reported, 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 "Take Off - Go Around". The aircraft had entered
the last 900 m of the runway when the aircraft started to lift off the ground.  Reports later found that
that the aircraft crossed the upwind end of the runway at just 276 feet.

Expected take-off and flight profile in green, actual flight take-off profile in red. Image AAIB

The rest of the flight was uneventful and proceeded to London Heathrow as expected, complete with its 208 passengers and 8 crew. When reviewing the flight, after takeoff, the crew realised they had entered a flex temperature of 79°C instead of 49°C.

During the takeoff performance data entry, the pilot flying is required to read the performance figures from the printed performance calculation. The pilot monitoring enters these into their Multipurpose Control and Display Unit with the pilot flying checking these are entered correctly on their MCDU screen. The commander was not sure if he said “79°” when he read the flex temperature or if he said the correct number and the co-pilot inadvertently pressed 7 rather than 4. He highlighted that the 7 and 4 keys are next to each other on the keyboard. He was not sure why he did not spot the error when he checked his MCDU but thought he may have been looking at the non-standard acceleration altitude. The commander highlighted that not many airports require a non-standard acceleration altitude so he may have been focusing on this rather than the flex temperature. During this process, the flight crew were briefly distracted by a call from the cabin crew and this may have been why the error was made or why it was not spotted. Even the simplest and smallest of distractions can have serious repercussions.

British Airways has since reminded its pilots of the dangers of distractions whilst entering critical flight data, it is also reviewing its takeoff performance data entry and checking procedures in order to ensure that there are sufficient opportunities in the procedures to trap any errors.

The information has been taken from the Air Accident Investigation Branch report on the incident published in May 2020.

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