The Indonesian flight which crashed shortly after take-off had suffered instrument problems the day before, according to a technical log obtained by the BBC.
A technical log from a flight from Bali to Jakarta on Sunday said an instrument was “unreliable” and the pilot had to hand over to the first officer.
The Boeing 737 airliner crashed into the sea with 189 people on board.
It went down after taking off from Jakarta. There is no sign of survivors.
The BBC has so far been unable to reach Lion Air, the low-cost airline which owns the plane, for comment.
Flight JT 610 was headed for the western city of Pangkal Pinang. Rescuers have recovered some bodies and personal items, including baby shoes. Families are being told to go to a hospital to identify the dead.
The incident is reported to be the first major accident involving a Boeing 737 Max – an updated version of the 737.
What was the instrument problem?
A technical log obtained by the BBC from the plane’s previous flight suggests that the airspeed reading on the captain’s instrument was unreliable, and the altitude readings differed on the captain’s and first officer’s instruments.
“Identified that CAPT [captain’s] instrument was unreliable and handover control to FO [first officer],” the log reads. “Continue NNC of Airspeed Unreliable and ALT disagree.”
The crew decided to continue their flight and landed safely at Jakarta.
Earlier Lion Air Chief Executive Edward Sirait said the plane had had an unspecified “technical issue” when flying from Denpasar in Bali to Jakarta, but he added that this had been “resolved”.
“If the plane was broken, it would have been impossible to clear the plane to fly from Denpasar,” he said. “When we received the flight crew’s report, we immediately fixed the problem.”
The airline operates 11 Boeing 737 Max 8 planes but the others have not had a similar technical problem and there is no plan to ground the fleet, he added.
What happened to the plane?
Flight JT 610 took off from Jakarta at 06:20 on Monday (23:30 GMT on Sunday).
It was due to arrive at Depati Amir airport in Pangkal Pinang an hour later but 13 minutes into the flight, authorities lost contact.
The pilot had asked to return to Jakarta’s Soekarno-Hatta airport, officials say.
The head of Indonesia’s disaster agency, Sutopo Purwo Nugroho, has tweeted images of debris and personal belongings that came from the aircraft and had been found floating in the sea.
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What do we know about those on board?
Lion Air said in a statement that the pilot and co-pilot had had more than 11,000 flight hours between them.
Three of the crew on board were trainee flight attendants and one was a technician.
Twenty employees from Indonesia’s finance ministry were also on board, the BBC has learned.
A ministry spokesperson said they had worked at the finance ministry offices in Pangkal Pinang but had been in Jakarta for the weekend.
What do we know about this aircraft?
The 737 Max series are the fastest-selling planes in Boeing’s history and there are four models – the Max 7, Max 8, Max 9 and Max 10.
The Boeing 737 Max 8 has been in commercial use since 2016.
The aircraft involved in the crash was made in 2018. It is a single-aisle plane used for short-haul travel.
In a statement, Boeing expressed sympathy for the victims and families and said it stood “ready to provide technical assistance to the accident investigation”.
Australia told government workers and contractors to stop using the airline until the findings of the investigation were out.
How is Indonesia’s air safety record?
Indonesia, a vast archipelago, is heavily reliant on air travel but many of its airlines have a poor safety record.
Established in 1999, Lion Air operates domestic flights as well as international routes to South East Asia, Australia and the Middle East.
It has had issues of safety and poor management in the past and was banned from flying into European airspace until 2016.
In 2013, Lion Air flight 904 crashed into the sea on landing at Bali’s International Airport. All 108 people on board survived. In 2004, flight 538 from Jakarta crashed and broke up on landing at Solo City, killing 25 people.
In 2011 and 2012 a number of pilots were found in possession of methamphetamines, in one incident hours before a flight.
Additional reporting by Stephen Fottrell
Lion Air crash: Jakarta Boeing 737 ‘had prior instrument error’