What happened
During the takeoff roll from runway 10, the crew did not reject the departure despite the automatic takeoff power control system (ATPCS) failing to arm properly. Shortly after liftoff at 1052LT, while climbing through 1,200 feet, a master warning was triggered as the left engine's power was reduced. This was followed by the uncommanded auto-feathering of the right engine and subsequent stall alarms.
In an attempt to manage the situation, the pilot flying reduced power on the remaining functional engine and eventually shut it down. The aircraft entered a steep left bank of approximately 90 degrees, striking a concrete bridge barrier over the Keelung River. The impact also struck a taxi on the bridge, injuring its two occupants. Following the collision with the bridge, the ATR 72-600 plunged into the river and was destroyed. The accident resulted in 40 fatalities, 15 survivors, and three individuals remaining missing.
Findings
Investigations identified that a hardware malfunction within the engine number 2 auto-feather unit (AFU), specifically compromised soldering joints, caused an intermittent signal discontinuity. This triggered an uncommanded ATPCS sequence that led to the propeller auto-feathering.
The crew failed to follow established emergency procedures, which led to the incorrect identification of the engine failure and the subsequent shutdown of the operational engine. Furthermore, the pilot flying's decision to disconnect the autopilot increased workload during a critical phase. The investigation also noted that the crew did not effectively respond to stall warnings or coordinate properly to manage the loss of thrust, ultimately leading to a stall-induced loss of control.