4 Years ago today: On 4 February 2015 a TransAsia Airways ATR 72-600 crashed at Taipei, Taiwan when the crew shut down the wrong engine after an engine failure; killing 43 occupants.

Date:Wednesday 4 February 2015
Time:10:54
Type: ATR 72-212A (ATR-72-600)
Operator:TransAsia Airways
Registration:B-22816
C/n / msn:1141
First flight:2014-03-28 (10 months)
Total airframe hrs:1627
Cycles:2356
Engines:Pratt & Whitney Canada PW127M
Crew:Fatalities: 4 / Occupants: 5
Passengers:Fatalities: 39 / Occupants: 53
Total:Fatalities: 43 / Occupants: 58
Aircraft damage:Destroyed
Aircraft fate:Written off (damaged beyond repair)
Location:5,3 km (3.3 mls) E of Taipei-Songshan Airport (TSA) (   Taiwan)
Phase:Initial climb (ICL)
Nature:Domestic Scheduled Passenger
Departure airport:Taipei-Songshan Airport (TSA/RCSS), Taiwan
Destination airport:Kinmen-Shang-Yi Airport (KNH/RCBS), Taiwan
Flightnumber:GE235

Narrative:
A TransAsia ATR-72-600 operating as flight GE235 from Taipei to Kinmen Island impacted a highway viaduct and the waters of the Keelung River near New Taipei City shortly after takeoff. Forty-three occupants on board the airplane suffered fatal injuries. Fifteen were injured.
The airplane took off from Taipei-Sung Shan Airport’s runway 10 at 10:51 hours local time and turned right, climbing to an altitude of 1350 feet. At 10:52 the master warning sounded in the cockpit associated with the right engine (no. 2) flame out procedure message. Some 26 seconds later the left hand (no. 1) power lever was retarded to flight idle. After twenty seconds the left engine condition lever was set to the fuel shutoff position resulting in left engine shutdown.
Instead of continuing the climbing right hand turn, the airplane had turned left and began losing altitude and speed with several stall warnings sounding in the cockpit. At 10:53, the flight contacted the Sung Shan Tower controller declaring a Mayday and reporting an ‘engine flameout’. The airplane then turned to the right while the crew attempted to restart the left hand engine.
This succeeded at 10:54:20 hours. Fourteen seconds later the stall warning sounded in the cockpit. Video footage of the accident show that the airplane banked almost 90 degrees left as it hit a taxi on a viaduct. Parts of the left hand wing broke off upon hitting the barrier of the viaduct. The airplane broke up as it impacted the Keelung River and came to rest inverted

Probable Cause:

Findings Related to Probable Causes:
Powerplant
1. An intermittent signal discontinuity between the auto feather unit (AFU) number 2 and the torque sensor may have caused the automatic take off power control system (ATPCS):
– Not being armed steadily during takeoff roll;
– Being activated during initial climb which resulted in a complete ATPCS sequence including the engine number 2 autofeathering.
2. The available evidence indicated the intermittent discontinuity between torque sensor and auto feather unit (AFU) number 2 was probably caused by the compromised soldering joints inside the AFU number 2.

Flight Operations
3. The flight crew did not reject the take off when the automatic take off power control system ARM pushbutton did not light during the initial stages of the take off roll.
4. TransAsia did not have a clear documented company policy with associated instructions, procedures, and notices to crew for ATR72-600 operations communicating the requirement to reject the take off if the automatic take off power control system did not arm.
5. Following the uncommanded autofeather of engine number 2, the flight crew failed to perform the documented failure identification procedure before executing any actions. That resulted in pilot flying’s confusion regarding the identification and nature of the actual propulsion system malfunction and he reduced power on the operative engine number 1.
6. The flight crew’s non-compliance with TransAsia Airways ATR72-600 standard operating procedures – Abnormal and Emergency Procedures for an engine flame out at take off resulted in the pilot flying reducing power on and then shutting down the wrong engine.
7. The loss of engine power during the initial climb and inappropriate flight control inputs by the pilot flying generated a series of stall warnings, including activation of the stick pusher. The crew did not respond to the stall warnings in a timely and effective manner.
8. The loss of power from both engines was not detected and corrected by the crew in time to restart an engine. The aircraft stalled during the attempted restart at an altitude from which the aircraft could not recover from loss of control.
9. Flight crew coordination, communication, and threat and error management (TEM) were less than effective, and compromised the safety of the flight. Both operating crew members failed to obtain relevant data from each other regarding the status of both engines at different points in the occurrence sequence. The pilot flying did not appropriately respond to or integrate input from the pilot monitoring.