What happened
On February 4, 2015, TransAsia Airways flight GE235, an ATR72-212A registered B-22816, crashed into the Keelung River while performing a regular public transport service from Taipei's Songshan Airport to Kinmen. During the initial climb phase, the aircraft experienced a sudden loss of control. Before impacting the water, the aircraft's left wing tip struck a vehicle on an overpass.
The accident resulted in 43 fatalities, including the three flight crew members, one cabin crew member, and 39 passengers. Additionally, 14 occupants of the aircraft sustained serious or minor injuries. The impact with the overpass also caused serious and minor injuries to the taxi driver and passenger.
The investigation
The investigation conducted by the Taiwan Transportation Safety Board (TTSB) examined the mechanical performance of the engine's auto feather unit (AFU) and the flight crew's response to the emergency. Investigators analyzed the sequence of events following the takeoff roll, specifically looking at the automatic takeoff power control system (ATPCS) and the crew's adherence to standard operating procedures (SOPs). The probe also reviewed TransAsia Airways' training programs, crew resource management (CRM), and the regulatory oversight provided by the Civil Aeronautics Administration (CAA).
Findings
Technical analysis revealed that an intermittent signal discontinuity in the engine number 2 auto feather unit, likely caused by compromised soldering joints, triggered an uncommanded autofeather sequence. This led to a significant loss of thrust during the climb.
Crucially, the flight crew failed to follow established emergency procedures to identify the malfunction. The pilot flying (PF) mistakenly reduced power on the remaining operative engine (number 1) and eventually shut it down. This resulted in a total loss of power from both engines. The crew did not detect or correct the dual engine power loss in time to restart the engine before the aircraft entered a stall. The investigation also noted that the pilot'1s decision to disconnect the autopilot increased workload, and the crew's coordination and threat and error management were ineffective during the crisis.