Story highlights

Pilot monitored flight as co-pilot flew AirAsia Flight 8501

Stall warning blared as plane climbed suddenly and until it crashed

Plane wobbled and veered left

Jakarta, Indonesia CNN  — 

Indonesian crews pulled out more bodies following last year’s crash of an AirAsia jet, raising the total to 100 so far, authorities said Sunday.

Those are the new details released by the Indonesia’s National Transportation Safety Committee in a news conference Thursday.

Though it’s common for the co-pilot to be in control of the aircraft, significant questions remain. Why did the plane start a sudden, steep ascent? Was bad weather a factor?

QZ8501 crashed December 28 as it flew from the Indonesian city of Surabaya toward Singapore. There were 162 people on board.

Stall warning sounded

The plane was in good condition and the entire crew was certified, said Mardjono Siswosuwarno, the chief investigator for the transportation committee.

The flight took off and cruised at 32,000 feet amid stormy weather. The pilot then asked the control tower whether the plane could ascend to 38,000 feet, according to the committee.

It then ascended from its cruising altitude to 37,400 feet in about 30 seconds in a steep ascent, the chief investigator said.

Commercial planes are not designed to ascend so quickly, and may have been climbing at a rate twice as fast as it should, analysts said.

AirAsia flight climbed quickly, then stalled before crash

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 can be triggered when the angle of attack, which is the angle at which the wing tackles the oncoming wind, hits 8 degrees.

The plane dropped quickly, falling 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.

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

Why was AirAsia jet the only one in trouble?

It’s unclear whether or when the initial report will be released.

Pilots’ experience

The French 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, a 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 8501 went down in an area of heavy thunderstorms last month while other planes nearby completed their journeys safely.

CNN’s Kathy Quiano reported from Jakarta, Indonesia, and Madison Park wrote from Hong Kong. CNN’s Saima Mohsin and Pamela Boykoff contributed to this report.