Indonesian Navy frogmen and underwater demolition unit personnel on a boat carrying body bags containing dead bodies from AirAsia flight QZ8501, are seen as bodies are lifted (unseen) to the Indonesian Navy vessel KRI Banda Aceh, at sea January 3, 2015. Ships searching for the wreck of an AirAsia passenger jet that crashed with 162 people on board have pinpointed two "big objects" on the sea floor, the head of Indonesia's search and rescue agency said on Saturday. [Photo/Agencies]

WEATHER FACTOR

The cause of the crash, the first fatal accident suffered by the AirAsia group, remains unexplained.

The plane was flying at 32,000 ft (9,753 metres) and the pilot had asked to climb to 38,000 ft just before contact was lost. When air traffic controllers granted permission to fly at 34,000 ft a few minutes later there was no response.

A source close to the investigation said radar data appeared to show the aircraft made an "unbelievably" steep climb before it crashed, possibly pushing it beyond the A320's limits.

Hadi Mustofa Djuraid, a transport ministry official, told reporters on Friday that authorities were also investigating the possibility that the pilot did not ask for a weather report from the meteorological agency at the time of take-off.

Indonesia AirAsia said in a statement that weather reports were printed in hard copy at the operations control centre at all its flight hubs, including Surabaya, and taken by the pilot to the aircraft before each flight.

An AirAsia spokeswoman declined to comment on whether the pilot had followed the procedure described in the statement.