EasyJet has underlined to crews the crucial importance of cross-checking performance calculations after three take-off incidents came under investigation in the space of four months.
The UK Air Accidents Investigation Branch says that pilots of an Airbus A320 erroneously used a full-length runway calculation when conducting an intersection departure from London Luton on 16 July last year.
It adds that it is looking into miscalculation events involving EasyJet A319s at Belfast on 25 June and Lisbon on 16 October.
Inquiries into the Luton incident found that the crew had originally programmed a full-length departure for runway 08, but revised the plan to an intersection take-off after a waiting aircraft became held up on the threshold.
While the captain told investigators that he had attempted to change the runway selection, the inquiry says a combination of his finger size and the calibration of the touchscreen on the electronic flightbag probably resulted in the change not being completed.
The captain also suggested he was distracted from confirming the runway selection by a decision to change the aircraft’s flap setting as part of the revised departure.
As a result the aircraft’s thrust settings and speeds remained incorrect for the intersection take-off, for which only 1,688m (5,538ft) of runway was available compared with the full length of 2,162m.
The aircraft reached its V1 decision speed with 580m of runway remaining, and the captain committed to the take-off after noticing the shortening distance. Flight-data recorder information showed the A320 became airborne at 148kt about 180m from the runway end.
Both the Belfast and Lisbon incidents involved crews calculating take-off data for an opposite-direction runway, with the Belfast departure also using full-length runway data for an intersection departure.
EasyJet has added a briefing note to operational flight plans, says the AAIB, to highlight the importance of cross-checking calculations after last-minute changes. It also plans to publish an article warning of the serious hazards in the carrier’s internal flight safety bulletin.