Indonesian divers on Thursday retrieved a flight data recorder from a Lion Air passenger jet that crashed into the shallow sea on Monday off the coast of the capital, Jakarta, killing all 189 people onboard.

The device is known as a black box, although these recorders are bright orange to aid in recovery. It could provide clues to what happened after the still new plane lost contact with ground staff just 13 minutes after taking off early on Monday from Jakarta, on its way to the tin-mining town of Pangkal Pinang.

One TV station showed footage of two divers after they surfaced, swimming to an inflatable vessel and placing the bright orange device into a large container that was transferred to a search and rescue ship. Navy divers interviewed on Indonesian television described recovering the flight recorder.

"I was desperate because the current below was strong but I am confident of the tools given to me," said navy 1st Sgt. Hendra, who uses a single name. After narrowing the possible location, "I started digging and cleaning the debris until I finally found an orange object," he said.

The device, which is orange as so-called black boxes are, would be handed over to Indonesia's transportation safety committee, authorities said.

It could take up to three weeks to download data from the black boxes and up to six months to analyze it, Soerjanto Tjahjono, the head of a national transport safety committee (KNKT), said on Wednesday.

Only "small pieces" of the aircraft had been found, the diver said, adding that the search had gradually closed in on the black box.

The plane's black boxes should help explain why the almost-new Boeing 737 MAX 8 jet went down in waters about 35 metres deep just off Jakarta.

Haryo Satmiko, deputy chief of the national transport safety panel, told Reuters earlier an underwater drone had detected an object suspected to be part of the fuselage in waters about 30 metres deep not far from the site where the aircraft lost contact.

Data from flight-tracking sites show the plane had erratic speed and altitude in the early minutes of a flight on Sunday and on its fatal flight Monday. Safety experts caution, however, that the data must be checked for accuracy against the flight data recorder.

Several passengers on the Sunday flight from Bali to Jakarta have recounted problems that included a long-delayed takeoff for an engine check and terrifying descents in the first 10 minutes in the air.

With media speculating on the airworthiness of the aircraft, the transport ministry suspended for 120 days Lion Air's maintenance and engineering director, fleet maintenance manager and the release engineer who gave the jet permission to fly on Monday.

Lion Air will also be subject to more intensive "on ramp" inspections compared with other airlines. Regulators will check 40 per cent of its flights at random, compared with 10 to 15 per cent for other airlines, minister Budi Karya Sumadi said.

Safety review ordered

President Joko Widodo had also ordered a review of all regulations relating to flight safety, Sumadi said.

The government was also considering reviewing airfares and may increase ticket prices charged by low-cost carriers, he said, without providing details.

A member of the Indonesian military places parts of the ill-fated Lion Air jet onto the deck of the ship during search operations. (Adek Berry/AFP/Getty Images)

Privately owned Lion Air, founded in 1999, said the aircraft had been in operation since August, adding that it had been airworthy and the pilot and co-pilot had 11,000 hours of flying time between them.

But according to the transport safety committee, the plane had technical problems on its previous flight on Sunday, from the city of Denpasar on the resort island of Bali, including an issue over "unreliable airspeed."

Lion Air chief executive Edward Sirait has acknowledged reports of technical problems with the aircraft, but said maintenance had been carried out "according to procedure" before it was cleared to fly again.

Investigators are looking into why the pilot had asked to return to base shortly after takeoff, a request that ground control officials had granted, although the flight crashed soon after.

Strong currents have hampered efforts to find the fuselage of the plane, with efforts complicated by the presence of energy pipelines in the area.