Almost 200 people are feared dead after Lion Air flight JT610, an almost new Boeing 737 MAX 8, lost contact with air traffic control 13 minutes after taking off from Indonesian capital Jakarta, and went down nine miles off the coast.
Search and rescue agency head Muhmmad Syaugi said: “We don’t know yet whether there are any survivors.
“We hope, we pray, but we cannot confirm.”
Mr Syaugi said mobile phones and life vests had been found in waters about 100ft deep near where the plane lost contact with ground officials.
He said: “We are there already, our vessels, our helicopter is hovering above the waters, to assist.
“We are trying to dive down to find the wreck.”
Ambulances are lined up at Karawang, on the coast east of Jakarta and police were preparing rubber dinghies. Fishing boats are also being used to help with the search.
At least 23 government officials were among the 189 board the plane, which an air navigation spokesman said had sought permission to turn back just before losing contact.
Edward Sirait, chief executive of Lion Air Group, said the aircraft had a technical problem on a flight from the resort island of Bali to Jakarta but it had been “resolved according to procedure”.
Mr Sirait declined to specify the nature of the issue but said none of its other aircraft of that model had the same problem.
He said Lion had operated 11 Boeing 737 Max 8s and it had no plan to ground the rest of them.
The accident is the first to be reported involving the widely sold Boeing 737 MAX, an updated, more fuel-efficient version of the manufacturer’s workhorse single-aisle jet.
Privately owned Lion Air said the aircraft had been in operation since August, was airworthy, with its pilot and co-pilot together having accumulated 11,000 hours of flying time.
The head of Indonesia’s transport safety committee said he could not confirm the cause of the crash, which would have to wait until the recovery of the plane’s black boxes, as the cockpit voice recorder and data flight recorder are known.
Soerjanto Tjahjono said: “The plane is so modern, it transmits data from the plane, and that we will review too. But the most important is the blackbox.”
Indonesian President Joko Widodo said authorities were focusing on the search and rescue, and he called for the country’s prayers and support.
The flight took off from Jakarta around 6.20am and was due to have landed in Pangkal Pinang, capital of the Bangka-Belitung tin mining region, an hour later.
Data from FlightRadar24 shows the first sign of something amiss was around two minutes into the flight, when the plane had reached 2,000 feet.
It descended more than 500ft and veered to the left before climbing again to 5000ft where it stayed during most of the rest of the flight.
It began gaining speed in the final moments and reached 397mph before data was lost when it was at 3,650ft.
Its last recorded position was about nine miles north of the Indonesian coast.
Indonesia’s worst air disaster was in 1997, when a Garuda Indonesia A300 crashed in the city of Medan killing 214 people.