(CNN) One of the two black boxes on a Russian military jet that crashed into the Black Sea with 92 people on board has been found, the country's Defense Ministry said Tuesday, according to the state-run Sputnik news agency.
The flight data recorder will be sent to a central research institute in Lyubertsy, where officials hope to get some insight into why the Tupolev Tu-154 plunged into the sea shortly after takeoff from Sochi on Sunday morning.
But it could take two weeks or more just to extract data from the recorder, aviation expert Col. Gen. Pyotr Belonozhko told Russia's state-run RIA Novosti.
"It all depends on the state of the black boxes," he said.
The flight data recorder was found 1,600 meters from the shore at a depth of 17 meters, the ministry said in a statement, as rescuers carry out a massive search operation in the sea.
The other black box -- the cockpit voice recorder -- is still missing.
The ministry has said there are probably no survivors.
The passengers
Those on board included 64 musicians from the army's official choir, the Alexandrov Ensemble; nine reporters; the head of the Spravedlivaya Pomoshch charity, Elizaveta Glinka; two federal civil servants; and eight crew members.
Read: The 'Red Army' choir loved by Russia
The choir was flying to Syria to perform for Russian air force pilots during the holiday season, the Defense Ministry has said.
Glinka was taking medicine and other supplies to a local hospital in Syria, her colleague and friend Dr. Sergey Kurkov told CNN affiliate RBC.
The investigation and search
Terrorism was not a likely cause of the crash, Kremlin spokesman Dimitri Peskov said Monday.
Russian Transport Minister Maxim Sokolov said it was assumed the plane had crashed due to technical malfunction or pilot error.
Russian military plane crashes near Sochi, Russia
On Tuesday, December 27, members of Russia's Emergency Ministry pack a flight recorder recovered from a Russian military plane that crashed Sunday into the Black Sea with 92 people aboard. Russia's transport minister said it was assumed the plane had crashed due to technical malfunction or pilot error -- not terrorism.
Emergency Ministry personnel prepare a submersible craft Tuesday to search for sunken wreckage and victims' remains. Thirteen bodies had been recovered from the Black Sea as of Tuesday morning.
A woman lights a candle Tuesday next to makeshift memorial in Sochi, Russia, for Russian activist Elizaveta Glinka, who was killed in the crash. Also presumed dead were nine journalists and more than 60 members of the Russian army's official choir, the Alexandrov Ensemble.
Wreckage from the Tu-154 plane is hauled from the Black Sea late on Monday, December 26.
Emergency crews continue search operations on December 26.
People visit a makeshift memorial to victims of the crash at a pier in Sochi on December 26. Russia is observing a national day of mourning for the eight crew and 84 passengers aboard.
A Russian police orchestra musician places a flower in tribute to members of the Alexandrov Ensemble outside their home stage building in Moscow on December 26. The popular ensemble was scheduled to perform for Russian pilots in Syria ahead of New Year's Day.
People hold a candlelight vigil for victims of the crash on Sunday, December 25, in Sochi.
Russian emergency personnel work near the site of the crash on December 25. The plane was en route from Moscow to Syria and had stopped in Sochi to refuel.
Russian emergency workers carry remains from the wreckage of the Tu-154 plane that crashed near Sochi on December 25.
Russian President Vladimir Putin, left, and Nursultan Nazarbayev, president of Kazakhstan, speak to members of the media in St. Petersburg, Russia, on December 25. Putin has ordered Prime Minister Dmitry Medvedev to lead an investigation of the crash, Russian news agency Sputnik reported.
Russian police secure the area near where the plane crashed. In addition to the ensemble, the plane was carrying eight crew, eight soldiers and nine journalists.
A man places a candle outside the building of the famed Alexandrov Ensemble, the Russian army's official dance and choir company, in Moscow.
A man places flowers outside the building of the Alexandrov Ensemble in Moscow on Sunday. Alexander Kibovsky, head of Moscow's culture department, called them "our cultural paratroopers."
Flowers lay in front of a photo of the Alexandrov Ensemble at the group's building in Moscow. "These people always performed in war zones, they wore uniforms, they brought kindness and light," Kibovsky said.
Two women stand outside Alexandrov Hall, a rehearsal room of the Alexandrov Ensemble, in Moscow on Sunday. The ensemble, established in 1928, has toured the world performing Russian folk songs, World War II anthems and patriotic music.
Photographs of Channel One, NTV and Zvezda TV journalists killed in the plane crash are seen outside the Ostankino Technical Center in Moscow.
A woman lights a candle at a memorial in Moscow.
The plane had taken off from Moscow and was headed to the Russian Hmeymim airbase in Latakia, Syria, where Russia has a large military presence. En route to Syria, the plane landed in Sochi to refuel.
Divers found the jet's fuselage about a mile offshore in the sea at the depth of 27 meters, RIA Novosti reported.
Thirteen bodies and 150 pieces of debris have been recovered so far, the Itar-Tass news agency reported, citing a source in security agencies.
About 3,500 people are taking part in the search, while 39 ships and cutters, 135 divers, seven deep-water vehicles and several aircraft have been deployed.
CNN's Mansur Mirovalev, Susannah Cullinane, Ashley Fantz,, Max Blau and Sarah Sirgany contributed to this report.