What happened
On 7 September 2012, an Airbus A320-214, registration EI-CVA, was performing a scheduled passenger flight from Milan to Dublin. While cruising at FL380 within the London Flight Information Region, the crew received Air Traffic Control (ATC) clearance to descend to FL340. However, the pilot flying had incorrectly set the altitude window to FL240.
As the aircraft descended, the pilot monitoring noticed the discrepancy and queried the clearance with ATC. During this period of confusion, the aircraft approached the intended level. In an attempt to arrest the descent and prevent an altitude excursion, the pilot disconnected the autopilot and applied a manual, abrupt pitch input using the side stick. This sudden maneuver caused vertical acceleration to spike to 1.7g. The resulting forces caused a cabin crew member in the aft galley to be thrown to the floor, resulting in a broken ankle.
The investigation
The AAIU examined flight data from the Digital Flight Data Recorder (DFDR) and cockpit communications from the Cockpit Voice Recorder (CVR). The investigation established that while the pilot monitoring had correctly read back the clearance to ATC, the information was not immediately recorded in the flight log. Furthermore, the investigation found that the pilot flying's manual control input was an instinctive reaction to the altitude error, but it was not the most appropriate method for leveling the aircraft.
Findings
- The flight crew failed to effectively cross-check the descent clearance, allowing the incorrect altitude to remain set in the Flight Control Unit.
- Communication between the pilots regarding the discrepancy was unclear, which delayed the recognition of the error.
- An abrupt manual pitch input was used to level the aircraft instead of utilizing more appropriate autopilot or flight guidance settings.
- The rapid change in g-forces during the maneuver directly caused the injury to the cabin crew member.