Divers had been searching the shallow waters off the coast of Jakarta for the flight data recorder, which should provide clues about what exactly happened when the plane lost contact with ground staff 13 minutes after taking off from the capital early on Monday.
The device was found intact on the muddy sea floor. Only small pieces of the aircraft were found but divers were able to close in on the equipment because of the “ping” signals it emitted.
“We dug and we got the black box,” a Navy sergeant, identified as Hendra, told broadcaster Metro TV on board a search vessel.
He said the search was “desperate because the current below was strong”.
The flight recorder will be handed over to Indonesia‘s transport safety committee, which is investigating what caused the Boeing 737 MAX 8 jet to plunge into the sea just weeks after entering service.
Flight JT610 had been making a one hour journey to the western city of Pangkal Pinang when it went down. The bodies of passengers and the crew have not yet been found but it is believed that there are no survivors.
The crash was the worst airline disaster in Indonesia since 1997 and renewed concerns about safety in its fast-growing aviation industry, which was recently removed from European Union and US blacklists.
Lion Air’s maintenance and engineering director, fleet maintenance manager, and the release engineer who gave the jet permission to fly on Monday have all been suspended for 120 days by the country’s transport ministry.
The budget airline will be subject to more intensive “on ramp” inspections compared with other airlines, authorities have announced. Regulators will check 40 per cent of its flights at random, compared with 10 to 15 per cent for other airlines, transport minister Budi Karya Sumadi said.
President Joko Widodo has also ordered a review of all regulations relating to flight safety, and his government is considering enforcing increases in ticket prices charged by low-cost carriers.
Privately-owned Lion Air, founded in 1999, said the jet which crashed had been in operation since August. It said the plane had been airworthy and the pilot and co-pilot had 11,000 hours of flying time between them.
But the transport safety committee said the plane had technical problems, including an issue with “unreliable airspeed”, on its previous flight from the city of Denpasar on the resort island of Bali on Sunday.
Lion Air chief executive Edward Sirait has acknowledged reports of technical problems, 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 Jakarta airport shortly after take-off, a request that ground control officials had granted shortly before the flight crashed.
It could be months before they know what caused the plane to crash.
Soerjanto Tjahjono, head of the transport safety committee, said it would take up to three weeks to download data from the black box and up to six months to analyse it.
An object thought to be part of the jet’s fuselage has also been found by an underwater drone about 30 metres (98 feet) deep close to where the aircraft lost contact with ground control.
The search has been complicated by strong currents and underwater energy pipelines in the area.