[INTERNATIONAL] Investigator: Co-pilot flew AirAsia Flight QZ8501

Jakarta, Indonesia (CNN)When AirAsia Flight QZ8501 crashed, the co-pilot was flying the plane. The pilot was monitoring the flight. And things may have gone wrong in a span of just THREE minutes and 20 seconds.

That's the assessment of Indonesia's National Transportation Safety Committee.

In a news conference Thursday, the agency released new details on the flight that crashed December 28 in the Java Sea as it flew from the Indonesian city of Surabaya toward Singapore. There were 162 people on board.

Stall warning sounded

The plane had been cruising at 32,000 feet. Around 11:12 p.m. UTC (coordinated universal time), the pilot asked the control tower whether it could ascend to 38,000 feet, according to the committee.

The plane was veering left and wobbling, said Ertata Lanang Galih, a senior pilot and investigator with the committee.

Flight QZ8501 then ascended 37,400 feet in about 30 seconds in a steep ascent, said Mardjono Siswosuwarno, the chief investigator for the transportation committee.

The stall warnings -- which blare the words "Stall, Stall" -- went on as the plane STARTED the steep climb and continued until it crashed, according to information on the flight data recorder. The voice warning doesn't always mean the aircraft has stalled, said Mardjono. The warning gets triggered when the plane's nose climbs more than 8 degrees.

The plane descended quickly, dropping to 24,000 feet out of radar detection.

Air traffic control permitted the plane to ascend to 34,000 feet about four minutes after the pilot's initial request.

The plane was in good condition and the crew were all certified, said Mardjono.

Officials have said previously that the aircraft climbed rapidly before it fell into the water.

Investigators have submitted their preliminary report into the crash, officials said. But Tatang Kurniadi, the chief of the National Transportation Safety Committee said they would not release the preliminary report during a Thursday news briefing.

It's unclear when the initial report will be released fully to the public.

Pilots experience

The co-pilot, Remi Emmanuel Plesel, had less experience than the captain.

Plesel, 46, had 2,275 hours with AirAsia Indonesia compared with the captain, known only as Irianto (as many Indonesians go by ONE name), who had 6,100 hours on AirAsia on the Airbus 320.

Irianto had more than 20,000 flying hours under his belt, having worked for another airline in Indonesia for 13 years before that, and had been a Indonesian Air Force pilot for a decade prior.

But it's common for the co-pilot to be in control of the aircraft.

"They usually rotate back and forth," said David Soucie, CNN aviation expert. "And that's a matter of maintaining experience. You wouldn't want ONE pilot to get all the flight time and the others not to be current on what's going on."

Indonesian aviation investigators are trying to establish why Flight QZ8501 went down in an area of heavy thunderstorms last month while other planes nearby completed their journeys safely.

Authorities have managed to recover 72 bodies from the sea, with 90 still unaccounted for, according to the airline.