The Tu-154’s main flight data recorder was found at the depth of 17 meters (56 feet), Russia’s Defense Ministry said. The ministry added that five more fragments of the crashed plane have been located.

The fragments have been found at the depth of 30 meters (98ft).

The fragments include the fuselage and parts of the engine.

At least 12 bodies from the plane crash have been recovered so far, the ministry said.

The black box was located some 1,600 meters (one mile) from shore by a FALCON underwater drone.

The black box has been delivered to the Central Research Institute of the Russian Air Force in the Moscow region. Specialists have already started to decode its data, Russian Transport Minister Maksim Sokolov said on Tuesday.

The flight data recorder that is already being studied recorded the main parameters of the flight until its destruction, “so its data is very important for further investigation,” the minister said. He added “there is information” that other black boxes from the Tu-154 were located by radar.

All possible causes of the crash will be investigated, the official said, adding that those included the quality of the fuel. Meanwhile, “there are no claims to the work” of the airport, he added.

The minister also said that “the plane disintegrated into several parts, so it is not possible to talk about any main part” to be searched for.

There have been unconfirmed reports that the aircraft crashed into the Black Sea at a speed of over 500km/h (310mph), TASS reported, citing a source in law enforcement. Before the aircraft crashed, the crew was allegedly trying to perform a maneuver to its right, but the plane’s nose was turned up too far, the source said.

A source told TASS earlier that one of the key theories as to why the plane crashed “is that foreign objects penetrated the engine,” adding that other possible causes, such as pilot error and technical failure, are also being investigated.

Some 45 ships, 15 underwater drones, 192 divers, 12 planes, and 5 helicopters are currently involved in the search, according to the ministry.

The Russian Defense Ministry’s Tu-154 plane crashed into the Black Sea minutes after takeoff from Sochi’s airport, killing 92 people on board. The plane was en route to Latakia, Syria, transporting 64 members of the world-famous Alexandrov Ensemble army choir, humanitarian workers and several media crews to take part in Christmas and New Year’s celebrations.

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The head of the choir, conductor and composer Valery Khalilov, as well as revered Russian humanitarian and charity activist Elizaveta Glinka (popularly known as Dr. Liza) were among the victims of the crash.

Russia on Monday observed a nationwide day of mourning for the victims of the crash.