What happened
On July 9, 2020, an Airbus A319-132, registration PT-TMO, operated by TAM Airlines S/A, was performing a descent toward São Paulo/Guarulhos (SBGR) from Aracaju (SBAR). During the descent, the aircraft's speed increased beyond the selected parameters, eventually reaching the maximum operating speed (VMO) of 350 knots.
To manage the speed, the flight crew transitioned to manual flight. The use of the sidestick to correct the aircraft's attitude resulted in a significant oscillation and a sudden increase in the positive load factor, which peaked at 2.23G. At the time of the maneuver, a flight attendant was standing in the galley area. The sudden vertical acceleration caused the crewmember to fall, resulting in serious injuries, including fractures to the left ankle and fibula.
Despite the incident, the aircraft remained undamaged and landed safely at the destination. The injured crewmember was later evacuated from the aircraft using an Ambulift.
The investigation
CENIPA's investigation focused on the flight data recorder (FDR) and cockpit voice recorder (CVR) to reconstruct the sequence of events. The analysis revealed that as the tailwind decreased, the aircraft's calibrated airspeed (CAS) began to rise toward the VMO. The autopilot initially attempted to pitch the nose up to maintain speed, but the aircraft eventually reached the VMO limit, causing the autopilot to disconnect.
The investigation examined the crew's manual inputs, noting a significant sidestick deflection. Investigators also reviewed the operational procedures regarding the "Open Descend" mode, which leaves a narrow margin for speed control when approaching VMO. The investigation noted that this occurrence shared characteristics with a previous similar event involving the same operator in 2018.
Findings
- The aircraft exceeded the selected speed of 340 knots, reaching a maximum CAS of 351 knots.
- The manual recovery maneuver involved high-amplitude sidestick inputs, leading to a positive load factor of 2.23G.
- The flight attendant was standing in the galley and was not restrained by a seatbelt at the time of the maneuver.
- The crew's manual control inputs contributed to a Pilot-Induced Oscillation (PIO) effect, which generated the G-load necessary to cause the fall.
- There was a lack of sufficient conditioning or training for managing manual flight in high-speed, high-workload descent scenarios.
Safety action
CENIPA issued the following recommendations to Brazil's National Civil Aviation Agency (ANAC):
- Coordinate with the operator to integrate training on the recognition and management of Pilot-Induced Oscillation (PIO) into A319/A320 pilot programs.
- Encourage A320 operators to implement safety practices for managing descents in "Open Descend/Speed" modes when using speeds close to the VMO.