What happened
On 16 February 2016, an Airbus A319-111, registration G-EZFA, was performing a scheduled passenger flight from Bristol Airport. The aircraft was carrying 125 passengers and 6 crew members. During the takeoff roll, a rattling noise was noted coming from the centre console, which prompted the co-pilot to place his hand on the area near the thrust levers to dampen the sound.
Shortly after lift-off, while the aircraft was approximately 46 ft above the runway, the commander instructed the co-pilot to raise the landing gear. Instead of moving the gear lever, the co-pilot moved the flap lever from position 1 to 0. As the flaps retracted, the aircraft's minimum selectable airspeed (VLS) increased rapidly. The commander, initially unaware of the flap retraction, lowered the aircraft's nose attitude and later applied takeoff/go-around (TOGA) thrust. This sequence led to a descent through 393 ft agl at a rate of 1,300 fpm, triggering the Ground Proximity Warning System (GPWS) 'don't sink' aural alert. The crew eventually recovered the aircraft into a climb, and the flight proceeded to its destination without further incident. There were no injuries and no damage to the aircraft.
The investigation
The investigation examined flight data and the aircraft's performance capabilities. It was noted that the aircraft's Alpha/Speed Lock function, designed to inhibit slat retraction at high angles of attack or low speeds, was not active because the flap lever had been moved to the 0 position. The investigation also reviewed the crew's performance calculations, which had utilized a reduced thrust takeoff procedure.
Findings
- The co-pilot was distracted by the rattling noise in the centre console during the takeoff roll.
- This distraction led to an action-slip, where a routine, well-learnt behavior was performed out of sequence.
- The co-pilot mis-selected the flap lever instead of the landing gear lever.
- The crew did not immediately realize the flaps had been retracted until after the TOGA thrust had been selected.