The pilot of a plane that crashed in Taiwan shut down the aircraft's only working engine and said "wow, pulled back the wrong throttle," seconds before the crash, investigators said.

TransAsia Airways Flight GE235 clipped a bridge and crashed into a river shortly after take-off from Taipei's Songshan airport on 4 February with 53 passengers and five crew on board.

Forty-three people were killed and 15 people survived.

Transcripts revealed by Taiwan's Aviation Safety Council showed the pilots tried to deal with an engine which had lost power, but reduced the thrust of the functioning engine. 

The report showed that the plane climbed to 365 metres before a warning alarm sounded. 

That alarm showed the plane's second engine underwent a "flameout at take off".

The failed engine was referred to as Engine Two by the warning signal, but the pilot at the controls said: "I will pull back Engine One throttle."

Both engines failed as the pilots tried to restart them in the few seconds before the crash. 

The last words from the black box recordings were the monitoring pilot shouting: "Impact, impact, brace for impact."

Images taken by a car dashcam showed the plane hitting an elevated road as it banked steeply away from buildings and crashed into the Keelung River.

"As the pilot pulled back the wrong throttle, for some time both engines were powerless," said Thomas Wang, Head of the Aviation Council.

Mr Wang also confirmed previous reports that the pilot had failed a simulator test for engine failure on take-off last year, but passed a later retake.

Investigators refused to name the pilot at the controls but reports at the time of the crash identified him as Liao Chien-Tsung.

Initially Mr Liao was hailed as a hero for steering the plane away from houses and into the river.

"Why the pilot did this, we don't know. That's the main task for our (final) analysis report," said Mr Wang over Mr Liao’s decision to pull back the throttle on Engine One.

The draft of that report is expected in November with the final report expected in April 2016.

Today’s evidence was described as a "factual report" giving more detail about the crash, but not attributing responsibility or drawing final conclusions about the cause.

Taiwan's aviation regulator ordered TransAsia pilots to take an oral test on basic operating and emergency procedures for the French-made aircraft after the initial findings pointed to pilot error.