Description

On 29 April 2011, an Airbus A321-200 being operated by Thomas Cook Airlines on a passenger service from Manchester UK to Iraklion, Greece took off in day Visual Meteorological Conditions (VMC) but failed to establish a climb at the expected speed until the aircraft pitch attitude was reduced below that prescribed for the aircraft weight which had been entered into the Flight Management System. No abnormal manoeuvres occurred and none of the 231 occupants were injured.

Investigation

An Investigation was carried out by the UK AAIB. It was noted that the operating crew were cross qualified on both the Airbus A320 and the Airbus A321 but had more frequently flown the smaller A320. It was reported that the aircraft commander acting as PF had considered the side stick control had felt heavy as he rotated the aircraft for take off from runway 05L at Manchester and, after lift off, he had noticed the Lowest Selectable Speed (VLS) indication on his Primary Flight Display (PFD) speed-scale increasing. He had reduced the aircraft pitch attitude and takeoff climb was continued, although at less than the expected rate since no additional thrust was added. When the aircraft reached cruise level, the flight crew checked the performance figures which had been used and realised that Zero Fuel Mass (ZFM) had been used in place of Takeoff Mass (TOM) for the takeoff performance calculations and, as a consequence, the FMS had been programmed with speeds which were too low -