What happened
On 7 January 2015, an Airbus A320-214, registration G-EZTE, was conducting a commercial passenger flight from London Luton to Paphos, Cyprus. While performing a visual approach to Runway 29, the aircraft's airspeed dropped significantly, triggering the ALPHA FLOOR autothrust protection.
During the descent, the crew utilized the Open Descent (OP DES) mode. As the aircraft entered the base turn, the co-pilot disconnected the autopilot but failed to deselect the flight directors. Because the aircraft was in OP DES mode, the autothrust continued to command idle thrust. As the airspeed decayed, the co-pilot applied an inappropriate aft sidestick input, leading to a high angle of attack. The sudden activation of TOGA thrust and the subsequent handover of control startled the commander, who initiated a go-around. During the climb, the aircraft encountered a potential conflict with another aircraft, triggering a TCAS Resolution Advisory (RA).
The investigation
The AAIB examined the flight crew's use of automation and the sequence of events leading to the speed decay. The investigation established that the crew had briefed the approach thoroughly but were not prepared for the delayed clearance to descend to circuit altitude.
Investigators found that the commander was distracted by a radio call from Air Traffic Control regarding revised go-around instructions at the moment the autopilot was disconnected. This distraction contributed to the omission of standard operating procedure calls and the failure to turn off the flight directors. Furthermore, the investigation noted that the co-pilot's situational awareness was reduced by an increasing workload during the turn.
Findings
- The primary cause was the failure to deselect the flight directors while operating in Open Descent mode, which left the autothrust commanding idle thrust.
- The crew's reliance on a manually created 4 nm range ring may have constrained their circuit pattern.
- The commander was distracted by ATC communications during the critical transition from autopilot to manual flight.
- The co-pilot's aft sidestick input during the speed decay exacerbated the high angle of attack.
- The activation of the ALPHA FLOOR protection and the subsequent go-around led to a TCAS RA conflict with another aircraft.