Divers have recovered a flight data recorder from the crashed Lion Air jet on the sea floor, a crucial development in the investigation into what caused the two-month-old plane to plunge into Indonesian seas earlier this week, killing all 189 people on board.

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.

(PA)

"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, in a television interview.

After narrowing the possible location, "I started digging and cleaning the debris until I finally found an orange object," he said, standing on the deck of a ship next to his diving mate.

The Boeing 737 MAX 8 plane crashed early on Monday just minutes after takeoff from the Indonesian capital Jakarta.

It was the worst airline disaster in Indonesia in more than two decades and renewed concerns about safety in its fast-growing aviation industry, which was recently removed from European Union and US blacklists.

The device recovered by divers is the flight data recorder and the search for the cockpit voice recorder continues, said Bambang Irawan, an investigator with the National Transport Safety Commission.

The location of the find was about 500 metres northwest of the coordinates where the plane lost contact and at a depth of 30 metres.

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. 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 recounted problems that included a long-delayed takeoff for an engine check and terrifying descents in the first 10 minutes in the air.

Lion Air has ordered 50 of the MAX 8 planes and one of its subsidiary airlines was last year the first to operate the new generation jet.

Investigators said a preliminary report into the accident could be released within a month but complete findings will take several months more.

Lion Air, a discount carrier, is one of Indonesia's youngest and biggest airlines, flying to dozens of domestic and international destinations.

It has been expanding aggressively in Southeast Asia, a fast-growing region of more than 600 million people.