Divers just off the coast of the capital Jakarta hauled the jet's flight data recorder to the surface Tuesday, with the hunt now focused on finding its cockpit voice recorder on the wreckage-littered seabed.

The devices could supply critical clues as to why the Sriwijaya Air Boeing 737-500 plunged about 10,000 feet (3,000 metres) in less than a minute before slamming into the Java Sea Saturday.

"The search continues today and we're hoping for a good result," Rasman MS, head of the search and rescue agency's crash operations, told reporters.

Black box data includes the speed, altitude and direction of the plane as well as flight crew conversations, and helps explain nearly 90 percent of all crashes, according to aviation experts.

So far authorities have been unable to explain why the 26-year-old plane crashed just four minutes after takeoff.

The US National Transportation Safety Board (NTSB) said it was sending investigators to Jakarta along with personnel from Boeing, the US Federal Aviation Administration and GE Aviation, which makes jet engines and other plane parts.

"(The) team has expertise in operations, human performance, airplane structures & systems," the NTSB tweeted.

More than 3,000 personnel are taking part in the recovery effort, assisted by dozens of boats and helicopters flying over small islands off the capital's coast, and a remotely operated vehicle to assist the divers.

"This operation is not over yet," Indonesian Military (TNI) chief Air Marshall Hadi Tjahjanto said late Tuesday.

"We'll keep searching for the victims and all the remaining parts of the fuselage, which we will try to retrieve."

Misinformation

Three more victims have been identified by matching fingerprints on file to body parts retrieved from the murky depths, authorities said Wednesday, including a 50-year-old female passenger and a 38-year-old off duty pilot.

The first victim, a flight attendant, was also identified through his fingerprints.

There were 10 children among the passengers on the half-full plane, which had experienced pilots at the controls as it left Jakarta bound for Pontianak city on Borneo island on a 90-minute flight.

Scores of body bags filled with human remains were being taken to a police morgue where forensic investigators hope to identify victims by matching fingerprints or DNA with relatives.

Authorities have so far said that the crew did not declare an emergency or report technical problems with the plane before its dive, and that the 737 was likely intact when it hit the water -- citing a relatively small area where the wreckage was scattered.

The crash probe was likely to take months, but a preliminary report was expected in 30 days.

Aviation analysts said flight-tracking data showed the plane sharply deviated from its intended course before it went into a steep dive, with bad weather, pilot error or mechanical failure among the potential factors.

The accident has spawned some misinformation online with a pair of pictures claiming that they show a baby who survived the weekend crash. The images actually show an infant rescued from a fatal 2018 boat disaster.