The flight data recorder from the Germanwings Airbus A320 that crashed in the French Alps on 24 March shows that the co-pilot on several occasions increased the speed of the aircraft during descent, according to French accident investigation agency BEA.
The agency, which is now reviewing the FDR, adds that the co-pilot also set the autopilot to descend the aircraft to an altitude of 100ft.
Work continues to determine the specific factual progress of the flight, says the BEA.
The aircraft, operating flight 9525 from Barcelona to Dusseldorf, began a steep descent shortly after reaching cruising altitude and then crashed into high terrain, killing 150 passengers and crew.
Investigators have said the co-pilot locked the captain out of the cockpit and then intentionally crashed the aircraft.