TAIPEI, Taiwan — A pilot described by colleagues as nervous and hasty mistakenly throttled down a still-running engine following a glitch with the other engine in an airline crash that killed 43 people in Taiwan in February, flight safety officials said Thursday.
A preliminary investigation into the Feb. 4 crash of TransAsia flight GE235 already had indicated that the pilot shut off the remaining engine after one of them went idle. But the account Thursday by Taiwan's Aviation Safety Council — while not assigning blame — added additional details about the crash and the background of the pilot, including that he had failed a flight simulator test as recently as May 2014.
Both the pilot and co-pilot died.
Minutes after takeoff in Taipei, a ribbon-like sensor connector in the automated flight system failed and put one engine into a mode that effectively cut its power to the aircraft, Taiwan's Aviation Safety Council Executive Director Thomas Wang told a news conference.
The engine's condition, useful in other cases to reduce torque, generated a flame-out warning in the cockpit 37 seconds after takeoff, according to a report by the council. However, it says the engine itself was technically still capable of providing power to the ATR-72 aircraft. The aircraft was also designed to fly on one engine.
"The sensor connector, in layman's terms, you would say was in a situation where it didn't connect normally," Wang said.
Seconds later, the pilot said he would pull back on the throttle to the plane's other engine, which showed no mechanical trouble, the council's report indicates. Normally, a pilot would throttle back to cut the flamed-out engine to avoid further problems and rely on the still-running engine for power.
"If engine two has flamed out, you would shut off engine two, that's normal logic," Wang said.
Eight seconds before the crash, the council's report states, the pilot said in Chinese: "Wow, pulled back on the wrong side throttle."
The pilot in command had failed a flight simulator test in May 2014 and passed it the following month with further training, the council's report says.
He had been described in post-crash interviews with colleagues as "a little nervous during line operations," and a person who "had a tendency of rushing to perform the procedures without coordination with the (co-pilot)," according to the report.
An automatic system to control power upon takeoff had not been armed while the plane was on the ground in Taipei but kicked in seconds later, the agency's report said. The pilot knew about this outage but authorized takeoff, the report shows. It was not clear if that glitch had any connection with the engine going idle.
The automatic takeoff power control system maker in the United States has joined Taiwan's investigation, Wang said.
The flight had left Taipei's Songshan airport for the outlying Taiwan-controlled islands of Kinmen. Video captured on dashboard cameras showed the plane flying on its side over an elevated road, clipping a fence, light pole and passing taxi shortly before plunging into the Keelung River in a heavily populated part of Taipei.
The flight was carrying 53 passengers, three crew members and two flight attendants. Fifteen people escaped the aircraft alive.
Another domestic TransAsia flight crashed on July 23 last year, killing 48 people aboard.
TransAsia said Thursday it has improved pilot training and the company's organization since the February crash.
Jon Beatty, CEO of the U.S.-based non-profit Flight Safety Foundation, has been invited to sit on TransAsia's aviation committee and give guidance, and all 61 ATR aircraft pilots have passed an "appropriateness examination," the company said in a statement.
TransAsia said it also has raised pay, "made active efforts" to develop skills, and formed an in-house safety inspection committee that meets every two weeks.
The Aviation Safety Council anticipates finishing a full investigation on the February crash by April 2016.