Investigators examine parts of Lion Air Flight 610 retrieved from the waters off Tanjung Priok in Jakarta, Indonesia. Picture: AP Photo/Tatan Syuflana

Jakarta, Indonesia - The smashed fuselage of a crashed Indonesian Lion Air jetliner may have been found, a top military commander said Wednesday, as Jakarta ordered the removal of the budget carrier's technical director and staff who cleared the doomed flight for take-off.

Authorities said they were confident sonar technology had pinpointed the location of the Boeing 737-MAX plane that plunged into the sea on Monday.

"We strongly believe we've determined the coordinates of the JT 610 fuselage," military chief Hadi Tjahjanto told reporters.

The search results will be announced at 7:00 pm (1200 GMT).

Authorities are racing to find the downed jet's location in water some 30-40 metres (100-130 feet) deep in the hope of also finding flight data recorders crucial to crash investigations.

Dozens of divers were taking part in the 1 000-strong personnel recovery effort along with helicopters and ships, but authorities have all but ruled out finding any survivors.

Boeing officials are expected to meet with Lion Air on Wednesday, after Indonesia ordered an inspection of the US plane maker's 737-MAX jets.

The downed plane, which went into service just a few months ago, was en route to Pangkal Pinang city when it crashed into the Java Sea off Indonesia's northern coast moments after it had asked to return to Jakarta on Monday.

On Wednesday, Indonesia's transport minister took the unusual step of ordering the removal of Lion Air's technical director and several other staff, citing government authority over the aviation sector.

"Today we will remove Lion's technical director from his duties to be replaced by someone else, as well as technical staff" who cleared the flight to depart, Budi Karya Sumadi told reporters.

Aviation experts say it is too early to determine what caused the accident.

But Lion's admission that the plane had an unspecified technical issue on a previous flight -- as well as the plane's abrupt nosedive just 12 minutes after takeoff -- have raised questions about whether it had any faults specific to the newly released model, including a speed-and-altitude system malfunction.

"The bigger picture here is that you've got a lot of American carriers flying the same aircraft," Stephen Wright, aviation expert at the University of Leeds, told AFP.

"Is there (a problem) that could affect other aircraft?"

'Worst in the world'

The crash has also resurrected concerns about Indonesia's patchy air safety record which led to a now-lifted ban on its planes entering US and European airspace.

Lion's co-founder Rusdi Kirana, now Indonesia's ambassador to Malaysia, said in a 2015 interview that "my airline is the worst in the world, but you don't have a choice".

Founded in 1999, the budget carrier capitalised on a boom in Indonesia's aviation industry, but has been plagued by safety woes and complaints over unreliable scheduling and poor service.

Lion was involved in a number of incidents including a fatal 2004 crash and a collision between two Lion Air planes at Jakarta's Soekarno-Hatta airport.

Lion Air Managing Director Daniel Putut said the airline had "many questions" for Chicago-based Boeing and they would discuss the delivery of 737-MAX models on still on order, Indonesian news website tirto.id reported.

Indonesia's biggest low-cost carrier announced this year it was buying 50 Boeing-737 MAX 10 jets for $6.24 billion.

Boeing suspended release of the fuel-efficient 737 MAX just days before its first commercial delivery last year due to an engine issue.

But the single-aisle jet was subsequently cleared for commercial delivery and has had thousands of orders from more than 100 customers worldwide.

Boeing and the US National Transportation Safety Board (NTSB) are taking part in the probe.

'Dad, I love you every day'

Search teams have been recovering personal effects and separating human remains from plane debris, sending the body parts -- including from an infant -- to hospital for DNA testing.

"He was the best husband in the world," 33-year-old Ningsi Ayorbaba said of her partner Ferdinand Paul Ayorbaba, who was on the flight.

"We had planned to celebrate our 15th anniversary in April...Today, I'm bringing in DNA samples."

Some 49 body bags filled with limbs and other remains have so far been recovered, authorities said.

Among the personal effects plucked from the water was a smartphone case with the image of a couple walking hand-in-hand over a bridge.

The story went viral online and the pair were later identified as Ine Yunita Savitri and her husband Wahjoe Noegrohantoro, who was on the downed jet. Savitri was not on the plane.

On Tuesday, their daughter Samantha posted the image to her Instagram account with the words: "Dad, I love you every day".

AFP