A domestic airliner that crashed in Taipei on Wednesday lost power in both engines, including one disabled by the pilots for unknown reasons, before it plunged sideways into a river, investigators said Friday based on the cockpit voice recorder.
The flight, which went down on its way from Taipei to an outlying island, marked locally based TransAsia Airways' second crash since July, and its fate has raised questions about air safety as Taiwan stakes a growing share of its economy on inbound tourism.
This week's crash killed at least 35 of the 58 people on board the flight, including the two pilots. Thirty-one passengers were tourists from China, the source of about 9.7 million Taiwan arrivals over the past seven years after just a trickle before then.
The doomed aircraft's crew cut one of the engines despite signs of trouble only in the other, the Taiwan government's Aviation Safety Council said after hearing a cockpit voice recording from the minutes before the crash.
Less than a minute after takeoff around 10:52 a.m., the ATR 72 propeller jet's cockpit sounded a general alarm and a signal indicated abnormality in the No. 2 engine, the Aviation Safety Council said in a statement based on the recorder. Seconds later a crew member mentioned throttling back on the No. 1 engine, the council said.
The flight was about 4,000 feet above ground by then, Taiwan's semi-official Central News Agency reported.
Seconds later the crew again mentioned pulling back the No. 1 engine throttle and confirmed flameout in the second engine. Flameout means the flames have stopped in an engine's combustion chamber, shutting it down so it cannot turn the propeller.
Within the next minute a deceleration alarm sounded in the cockpit and a crew member confirmed that the first engine was auto-feathering with its fuel cut, the statement said. Feathering means rotating a propeller's blades parallel to the airflow to reduce drag in the event of an engine failure.
"The pilot did not deal with the No. 2 engine, then as you can see, [the pilot] reduced acceleration on the first engine and then shut it down in the end," Thomas Wang, head of the council, told a news conference Friday.
The pilot then called a "mayday" distress alert and reported "flameout," the council statement says. By 10:54 a.m., about a minute before the crash, a crew member was yelling repeatedly to restart, it adds. The voice recording stops after picking up another general alarm.
Council officials said they had not yet determined a reason for the crash or for the actions taken in the minutes beforehand.
"The investigation goes in several phases, and now we're in the data collection phase," Wang said later Friday. "When we get to the analysis phase, we'll look at why things happened. I can't say anything now about cause."
An investigation made up of dozens of people, including representatives of the plane's manufacturer ATR and engine maker Pratt & Whitney Canada, will look into the crash over a year to 18 months before releasing a cause.
TransAsia officials say the plane had been used less than a year. An ATR 72 also operated by TransAsia crashed in an outlying Taiwan-controlled island chain in July, killing 48.
Wednesday's flight GE235, with 53 passengers and five crew members aboard, grazed a bridge and a moving taxi before crashing into the Keelung River. About 190 divers have plumbed the cold, murky river to find bodies submerged near the crash site.
Eight people were missing as of late Friday and 15 were confirmed to have survived. The taxi driver and a passenger were hurt.
In a sign of concern for the passengers from China, Taiwan Vice President Wu Den-yih paid respects at a funeral home where some of the victims' relatives were visiting Friday.
President Ma Ying-jeou's office had warned Thursday that air safety problems "affect trust in our tourism climate among tourists from outside Taiwan."