AirAsia jet's fuselage may have been found

Indonesian divers are investigating an object believed to be the fuselage of the crashed AirAsia jet and the resting place of most of the victims.

Flight QZ8501 crashed in the Java Sea on December 28 in stormy weather during a short, routine flight from the Indonesian city of Surabaya to Singapore with 162 people on board.

Both black boxes, the flight data recorder and cockpit voice recorder, were recovered this week after a frustrating, lengthy search often hampered by bad weather. They should provide investigators with vital information about what caused the crash.

Scores of divers on Wednesday shifted their focus to investigating an object thought to the jet's main body, which was earlier spotted on sonar scans and is lying about three kilometres from where the plane's tail was found.

Finding the fuselage of the Airbus 320-200 is seen as vital, as most of the victims are believed to be still trapped inside. Just 48 bodies have so far been recovered.

Search and rescue agency official SB Supriyadi said if the object, which is lying about 30 metres under water, turned out to be the fuselage, divers would examine how it could be raised from the water.

"If it is not too heavy, we may lift the whole piece and evacuate the victims," said Supriyadi, who is coordinating what has been a huge, international search.

"If it's too heavy, we may then swim into the fuselage and pull out the bodies one by one before lifting it."

But he cautioned it would be a complex operation that could take several days.

"Retrieving the main part of the body poses a different challenge to retrieving the black boxes. We are working with larger plane parts and then there's a possibility of victims trapped inside," he said.

The so-called black boxes - which are actually orange in colour - have been flown to Jakarta, where Indonesia's National Transport Safety Committee is leading a probe into the accident, helped by experts from countries including France and the US.

The country's meteorological agency has said bad weather may have caused the crash but only the black boxes will be able to provide definitive answers.

Investigators have started retrieving data from the recorders and converting it into a usable format, which will take around a week, before the lengthy analysis process can begin, committee head Tatang Kurniadi said.

The flight data recorder holds a wealth of information about every major part of the plane, with details such as the jet's speed and the direction it was heading in, while the cockpit voice recorder stores radio transmissions and sounds in the cockpit.

Divers on Tuesday also spotted what they believe is one of the plane's engines, which could provide further clues about what caused the accident.