A black box from the crashed Indonesian passenger jet has been recovered, officials said Tuesday, a discovery that could offer critical clues to explaining why the plane with 62 people aboard slammed into the sea.

Divers just off the coast of the capital Jakarta hauled the jet's flight data recorder to the surface, as the hunt continues for its cockpit voice recorder.

Indonesian investigators are combing through the wreckage of the crashed Sriwijaya Air 737 to try and explain why it went down
Indonesian investigators are combing through the wreckage of the crashed Sriwijaya Air 737 to try and explain why it went down AFP / ADEK BERRY

Indonesian transport minister Budi Karya Sumadi told a live television briefing that the box had been found -- after 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.

An AFP reporter on a navy ship said investigators started picking up strong signals from an area where they were searching, with divers able to retrieve the box in about an hour from the wreckage-littered seabed.

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

Divers are grappling with strong currents and poor weather to search for bodies and wreckage on the sea floor
Divers are grappling with strong currents and poor weather to search for bodies and wreckage on the sea floor AFP / Demy Sanjaya

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

Sumadi added officials believe the cockpit voice recorder is nearby that of flight data recorder.

"We strongly believe it'll be found soon," he said.

IMAGESOfficials from Indonesia's National Transportation Safety Committee on Tuesday examine debris recovered during the search for Sriwijaya Air flight SJY182 which crashed into the sea minutes after taking off from Jakarta at the weekend.
IMAGESOfficials from Indonesia's National Transportation Safety Committee on Tuesday examine debris recovered during the search for Sriwijaya Air flight SJY182 which crashed into the sea minutes after taking off from Jakarta at the weekend. AFPTV / Bagus SARAGIH

Some 3,600 personnel are taking part in the recovery effort, assisted by dozens of boats and helicopters flying over small islands off the capital's coast.

The agency deployed a remotely operated vehicle to assist the divers.

Relatives of victims were distraught as they provided DNA samples to help authorities identify the recovered remains
Relatives of victims were distraught as they provided DNA samples to help authorities identify the recovered remains AFP / BAY ISMOYO

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 distraught relatives -- some held out hope of survivors.

Some 3,600 personnel are taking part an effort to recover the wreckage and remains from an Indonesian airliner that crashed in the waters off Jakarta
Some 3,600 personnel are taking part an effort to recover the wreckage and remains from an Indonesian airliner that crashed in the waters off Jakarta AFP / Azwar Ipank

"We haven't accepted it yet," Inda Gunawan said of his brother Didik Gunardi who was on the doomed Saturday flight.

"Our family is still hoping for a miracle that he is still alive."

Authorities have identified flight attendant Okky Bisma, 29, as the first confirmed victim after matching fingerprints from a retrieved hand to those in a government identity database.

Factfile on what we know about the Sriwijaya Air Boeing 737 that crashed on January 9, shortly after take-off.
Factfile on what we know about the Sriwijaya Air Boeing 737 that crashed on January 9, shortly after take-off. AFP / John SAEKI

"Rest in peace up there darling and wait for me... in heaven," Okky Bisma's wife Aldha Refa wrote on Instagram.

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.

A transport safety agency investigator has said 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.

Search-and-rescue agency chief Soerjanto Tjahjono echoed that view earlier Tuesday, pointing to the relatively small area where debris was scattered in about 23 metres (75 feet) of water.

"The size is consistent with the assumption that the plane didn't explode before hitting the water," he added.

"The damage seen on the retrieved fan blade also shows that the engine was still working" at the time of the crash.

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.

Sriwijaya Air, which flies to destinations in Indonesia and across Southeast Asia, has had safety incidents including runway overruns.

But it has not had a fatal crash since starting operations in 2003.

Its CEO has said the jet, which was previously flown by US-based Continental Airlines and United Airlines, was in fit condition.

In October 2018, 189 people were killed when a Lion Air Boeing 737 MAX jet crashed near Jakarta.

That accident -- and another in Ethiopia -- led to the grounding of the 737 MAX worldwide.

The 737 that went down Saturday was first produced decades ago and was not a MAX variant.