What happened
On July 20, 2014, an Airbus A319-111, registration HB-JZQ, was operating a flight from Olbia to Basel-Mulhouse. During the descent phase, the aircraft's target speed reference failed to transition from Mach to knots. As a result, the aircraft's speed steadily increased toward its maximum operating limit.
In response to the approaching speed limit, the pilot performed a sudden and forceful pitch-up maneuver using the left sidestick, pulling it all the way to the stop. This abrupt action generated a vertical load factor of 2.33 g. The sudden acceleration caused three of the four cabin crew members to be thrown to the floor, leaving one crew member with a serious injury to the left ankle.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight data and cockpit voice recordings to determine why the aircraft's speed increased and why the pilot's reaction was so extreme. The investigation focused on the automation's failure to perform the 'crossover' from Mach to speed mode and the pilot's management of the descent parameters.
Findings
- The primary cause of the accident was the abrupt pull on the left sidestick to the full stop, which created the high-g acceleration.
- The automation failed to automatically execute the crossover from Mach to speed mode while in selected speed mode.
- The pilot in command failed to properly monitor flight parameters and managed the descent settings inappropriately as the aircraft approached its maximum operating speed.
- The investigation noted that while overspeed prevention and recovery procedures exist, they are not classified as memory items, meaning they require reference to written documentation, which is difficult during dynamic flight situations.
Safety action
Following the findings, the investigation highlighted a safety deficit regarding how crews are trained for overspeed scenarios. It was noted that pilots may feel a psychological pressure to avoid crossing speed limits at all costs, leading to instinctive, aggressive maneuvers. The report suggests that EASA should ensure manufacturers engage in training and sensitization efforts for Airbus A320 series crews regarding overspeed situations.