A pilot described by colleagues as nervous and hasty mistakenly switched off a plane's only working engine in the TransAsia airline crash that killed 43 people in Taiwan in February, flight safety officials said on Thursday.
"Wow, pulled back on the wrong side throttle," the pilot was heard saying in Chinese on the flight's voice recording eight seconds before the crash.
A preliminary investigation into the February 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 released on 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.
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 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.
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. But seconds after the engine cut out, 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.
He did not appear to realize his mistake until it was too late, reported Reuters, then trying to restart the engine before a junior first officer, who was also in the cockpit as part of his training, said: "Impact, impact, brace for impact."
The plane then lurched to one side, clipped an overpass and a taxi and crashed upside down in a shallow river in downtown Taipei. Out of the plane's 53 passengers, three crew members and two flight attendants, only 15 escaped the aircraft alive. Both pilots died.
The pilot 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.
Another domestic TransAsia flight crashed on July 23 last year, killing 48 people aboard.
Since the crash, Taiwan's Civil Aeronautics Administration has put all 55 of TransAsia's ATR pilots through oral proficiency tests on how to handle an aircraft during engine failure, said Reuters.
All but one of the pilots passed the tests, although some needed more than one attempt. The lone failure was demoted in rank to vice-captain from captain.
TransAsia said Thursday it has improved pilot training and the company's organization, and formed an in-house safety inspection committee, since the February crash.
The Aviation Safety Council anticipates finishing a full investigation on the February crash by April 2016.
The Associated Press contributed to this report.