The pilots of an Indonesian passenger jet were arguing about the plane's speed moments before it crashed last month, a senior investigator has said.
The blaze took two hours to put out and gutted the jet
Tatang Kurniadi told Australian television that the co-pilot wanted to turn around instead of landing.
The two pilots, who both survived, were flying together for the first time.
The Garuda Airlines Boeing 737-400 crashed as it landed at Yogyakarta airport on 7 March, killing 21 of the 140 people on board.
Survivors and witnesses said the plane came in to land at a high speed before it overshot the runway into a rice field and burst into flames.
Passengers and crew scrambled for safety through emergency exits as fire raced through the cabin, leaving the wreckage a gutted shell.
The voice and flight data recorders are being analysed in Australia.
"There was also some argumentation between the co-pilot and the pilot and captain relating with the speed and flaps," Mr Kurniadi told the Nine Network.
He said the wing flaps, which help slow the plane down for landing, did not jam and it appeared it would have been possible to circle around for another attempt at landing.
The retrieved black boxes were immediately flown to Australia
He said he did not know why the pilot chose to continue with the landing.
"I worry that this accident came from the absent-mindedness of the cockpit," he said.
He said the pilot was very experienced with more than 15,000 flying hours. The co-pilot was a "young pilot with just about 2,000 flying hours".
The cockpit voice recorder was badly burnt in the crash but investigators said last month that they had been able to recover the last 30 minutes of the crew's conversation.
Mr Kurniadi said he expected the investigation to be completed in a month.