Indonesian soldiers and rescue members carry coffins of passengers, who were onboard AirAsia Flight QZ8501, at Iskandar airbase tarmac in Pangkalan Bun, January 19, 2015. [Photo/Agencies]

Investigators said the cockpit voice and flight data recorders showed that the plane had been cruising at a stable altitude before the accident. The aircraft was in sound condition when it took off, and all crew members were properly certified, they said.

"The plane was flying before the incident within the limits of its weight and balance envelope," Mardjono said. "While the flight crew had valid licences and medical certificates."

Indonesia has previously said the aircraft climbed abruptly from its cruising height and then stalled, or lost lift, before plunging out of control into the sea.

NTSC chief Tatang Kurniadi told the same Jakarta news conference that Indonesia had submitted its preliminary report on the crash to the International Civil Aviation Organization (ICAO) on Wednesday, as required under global aviation rules.

The report, which has not been made public, was purely factual and contained no analysis, he said, adding that the full, final report would take at least 6-7 months to complete.

On Wednesday Indonesia said the search for dozens of victims still unaccounted for could end within days if no more bodies were found.

A multinational search and recovery operation has found 70 bodies in the Java Sea and had hoped to find more after finding the fuselage of the plane. But days of rough weather and poor underwater visibility hampered navy divers' efforts.