Accident investigators say main cause of Taipei air crash was engine failure
Investigators in Taiwan say flight data shows one engine 'flamed out' but other was shut down manually, despite operating normally
Taiwan's Aviation Safety Council yesterday said it was investigating what caused both engines on TransAsia Flight GE235 to shut down and send the aircraft crashing into a river in northern Taiwan, killing at least 35 people.
Council chief Thomas Wang said it was too early to say if human error was a factor.
The announcement came amid local media speculation that a crew member's error compounded the flight's problems.
Wang said both engines of the ATR 72-600 turboprop lost power before the aircraft clipped a bridge and crashed into the Keelung River in Taipei on Wednesday with 58 people on board, including 31 from the mainland.
The crash occurred four minutes after the Quemoy-bound aircraft took off from Taipei Songshan Airport.
Releasing initial findings, Wang said the plane's voice and flight data recorders indicated the plane flashed a "flame-out" signal for its right engine soon after take-off, but its left engine was also shut down manually.
A flame-out is when the flame in an engine's combustion chamber goes out, stopping the propeller.
"Engine No 2 [right] flashed a master warning and … reduced thrust to the propeller," Wang said. "But data retrieved from the cockpit voice recorder and communication with the air control tower showed that engine No 1 [left] was shut off for an attempted restart," he said, adding that the left engine was working normally.
Both engines stopped and attempts to restart the left one failed, Wang said. The plane then lost power and crashed.
Pilot Liao Chien-tsung had been hailed as a hero for steering the plane away from buildings.
Britain-based aviation safety expert Chris Yates said there could have been a misunderstanding in the cockpit.
"It sounds like a significant amount of confusion in the cockpit. For the signal to flash up on one engine and for the other to be shut down manually suggests that the pilot or co-pilot was confused and shut down the wrong engine completely," he said.
"All of this happened so quickly at such a critical moment. The aircraft had just taken off, then things started to go wrong very quickly, and during this time, because he's doing so many things at once, it's very easy to make a mistake."
Greg Waldron, from aviation news service Flightglobal, said the flight data indicated the crew mistakenly switched off the wrong engine.
Waldron said the aircraft was designed to continue flying even with just one engine.
Searchers continued looking for bodies yesterday, with divers finding the remains of one female and three males.
Meanwhile, Taiwan's Civil Aeronautics Administration said TransAsia had failed to meet one-third of the improvements ordered after another of its planes crashed in July, killing 48 people.
From the GE235 flight data recorder
10.51am +12.7s: Receives take-off clearance
10.52 +38.3: Main alarm for engine 2
10.52 +43.0: Pilots mention easing power for engine one
10.53 +00.4: Pilots discuss procedure for handling engine flame-out
10.53 +06.4: Pilots again mention easing power for engine one
10.53 +07.7: Pilots confirm flame-out of engine two
10.53 +12.6 to 10.53 +18.8: Alarm for loss of speed goes off for first time in cockpit
10.53 +19.6: Pilots mention engine one propeller is auto-feathering and power to that engine has been cut
10.53 +21.4 to 10.53 +23.3; 10.53 +25.7 to 10.53 +27.3: Speed loss alarm
10.53 +34.9: First mayday - "mayday mayday engine flame-out"
10.53 +55.9 to 10.53 +59.7; 10.54 +06.1 to 10.54 +10.1: Speed loss alarm
10.54 +09.2: Pilots repeatedly call for re-ignition of engine one
10.54 +12.4 to 10.54 +33.9: Speed loss alarm
10.54 +34.4: Main alarm goes off for second time in cockpit
10.54 +34.8: Unknown noise recorded
10.54 +36.6: Voice recorder stops