The pilots of the doomed Lion Air jet which crashed last year frantically pored through a handbook to understand why the jet was in free fall.
The first Boeing 737 Max crash killed all 189 people on board in October and has taken on extra relevance following the second deadly accident just months later.
More details from the cockpit voice recorder were revealed by people with knowledge, and suggests pilot training was lacking in the case of the Lion Air crash.
Investigators have already acknowledged ‘similarities’ in the two crashes.
It is the first time contents of the Lion Air voice recorder have been made public.
Like the later Ethiopian Airlines incident, the Lion Air jet crashed minutes after take-off.
The first officer indicated a ‘flight control problem’ to air traffic control just two minutes after take-off.
As the captain searched for the correct t procedure in the handbook to prevent the anti-stall mechanism from forcing the plane downwards, the first officer was ultimately unable to control the plane, sources said.
"It is like a test where there are 100 questions and when the time is up you have only answered 75, so you panic. It is a time-out condition," said one of the sources.
Data from the cockpit voice recorder has only now been revealed and was not included in the preliminary report as the black box was only recovered from the ocean floor in January.
