Ten TransAsia pilots have been suspended after failing tests on what to do in the event of aircraft engine failure.
Taiwan's aviation regulator said 10 of TransAsia's 49 ATR pilots had failed oral proficiency tests on handling the plane during engine failure.
A further 19 pilots did not take the test, due to either sickness or because they were not in Taiwan, the Civil Aviation Authority (CAA) said.
The Taiwan government has ordered all airlines to review safety protocols and the 29 pilots who failed or did not sit the test have been suspended from their duties, according to Reuters.
TransAsia chief executive Peter Chen condemned the results as “not acceptable for us”. He told a news conference: "We will definitely strengthen their training."
Tests were ordered after the TransAsia flight GE235 crashed into a river in Taipei, killing at least 42 of the 58 passengers and crew on board.
Initial data indicates that the plane lost power in one engine just minutes after take-off from Taipei's Songshan airport.
In pictures: TransAsia crash
In pictures: TransAsia crash
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'Dash cam" footage posted on the internet of plane crash in Taiwan
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The plane clipped a taxi before crashing into the river
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Rescuers lift the wreckage of the TransAsiaAirways plane out of the Keelung river
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Picture from Taiwan television shows the damage to the car that the plane hit
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Rescuers search for survivors moments after the TransAsia plane crashed into a river in New Taipei City this morning (Reuters)
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Rescuers use dinghies to survey the wreckage of the plane's body as it floats on the river in downtown Taipei (REUTERS/Pichi Chuang)
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Soldiers remove aeroplane parts of the TransAsia flight 235 crashed this morning (REUTERS/Pichi Chuang)
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An ambulance arrives to take away survivors from the crash that saw 12 die and many more injured (REUTERS/Pichi Chuang)
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Bodies are removed from the plane by Taiwanese rescue workers (REUTERS/Stringer )
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A man walks next to the wreckage of the TransAsia Airways plane which clipped a bridge before falling into the river February 4, 2015. (REUTERS/Stringer)
The crew then shut down the other engine, which was working, and attempted to restart it shortly before the aircraft crashed.
Twin-engine aircraft can fly with just one working engine, and the authorities have not released any information from the recorders that indicates why the pilots shut down the working engine.
The last communication from one of the TransAsia flight 235’s pilots was "Mayday Mayday engine flameout", according to an air traffic control recording on liveatc.net.
It was the second TransAsia ATR crash in seven months, and the fifth crash involving the airline since 1995.
Additional reporting by agenciesReuse content