The crew of a twin-propeller TransAsia plane faced a problem with one engine but restarted the other, investigators said on Friday, as it emerged the plane suffered a lack of thrust before crashing into a river in Taipei, killing 35 people, Reuters reported.
The reason for the pilots' action was unclear but a combined lack of thrust caused the almost-new turboprop ATR 72-600 to stall soon after take-off, Aviation Safety Council officials told a news briefing after a preliminary examination of the black box flight-data and voice recorders.
The plane, which can fly on one engine, was carrying 58 passengers and crew when it lurched nose-up between buildings, clipped an overpass and a taxi with one of its wings and then crashed upside down into a shallow river on Wednesday. Fifteen people survived.
The black boxes showed that the plane warned five times of stalling before the crash in the center of Taipei, according to findings by the council.
The right engine entered a state called "auto-feather", in which it reduced thrust to the propeller, Thomas Wang, managing director of the council, said.
The flight crew then reduced acceleration to the left engine, turned it off and then attempted to restart it, but it did not gain enough thrust.
There was no word on what may have been going through the pilots' minds or what the instruments may have been telling them, but evidence presented so far will raise questions over whether they accidentally cut the wrong engine.
"The first engine experienced a problem 37 seconds after take-off at 1,200 feet," Wang said.
He said the pilot had announced a "flameout", which can occur when fuel supply to an engine is interrupted or when there is faulty combustion, but there had not been one according to the data.
"The flight crew stepped on the accelerator of engine 2 (righthand side)... The engine was still operating, but neither engine produced power."
He said the aircraft could fly with one engine. The plane was powered by two Pratt & Whitney PW127M engines. Pratt & Whitney is part of United Technologies.
A fuller report on the crash will be available in next 30 days, with a final report expected in the next three to six months.