A black box from the crashed Lion Air jet has been recovered, authorities said yesterday, a find that could be critical to establishing why a brand new jet plunged into the Java Sea shortly after take-off, killing 189 people on board.

Divers plucked the orange data recorder from the ocean and placed it in a plastic tub as search teams continued to scour the seabed for the fuselage of the Boeing-737 MAX 8, which crashed off Indonesia's northern coast on Monday and had only been in service a few months.

There have been no survivors and only body parts have been found so far.

This picture from Indonesia media agency "detikcom" shows officials displaying part of the ill-fated Lion Air flight JT 610's black box, an FDR (flight data recorder), after it was recovered from the Java Sea, during search operations in the waters off Karawang on November 1, 2018. One black box from the crashed Lion Air jet has been recovered, the head of Indonesia's National Transportation Safety Committee said on November 1, which could be critical to establishing why the brand new plane fell out of the sky. Photo: AFP

Relatives are desperate to be able to say goodbye to their loved ones and the first funeral for one of the passengers was held yesterday.

But many others have yet to be located and analysts hope further victims could still be found with the bulk of the wreckage.

"I assume that there will be a lot of bodies still strapped into the seats," aviation analyst Dudi Sudibyo told AFP.

Dozens of divers are taking part in the massive recovery effort along with helicopters and ships, but authorities have all but ruled out finding any survivors.

The black boxes, which airlines are required to install, offer investigators their best chance of discovering why such a new jet crashed. The devices record information about the speed, altitude and direction of the plane as well as flight crew conversations.

Authorities say a flight data recorder was recovered, but they were still looking for the cockpit voice recorder.

The single-aisle Boeing plane, which was on its way from Jakarta to Pangkal Pinang city, is one of the world's newest and most advanced commercial passenger jets.

Despite the name, black boxes are in fact bright orange with reflective stripes. They are built to survive at vast depths and in extreme heat, and are fitted with a beacon which can emit a signal for one month.

Black boxes help explain nearly 90 percent of all crashes, according to aviation experts.

"Data from the plane -- the engine, all the instruments -- are recorded there," Sudibyo said. "If there is an anomaly, some technical problem, it is recorded there too."

Passengers' remains are being sent to hospital for DNA comparison to relatives.

Aviation experts are puzzled by the accident but say it's too early to determine what caused the crash.

Lion's admission that the jet had an unspecified technical issue on a previous flight -- as well its abrupt fatal dive -- have raised questions about whether it had faults specific to the newly released model, including a speed-and-altitude system malfunction.