The flight data recorder of the Russian military airliner which crashed in the Black Sea on Sunday has been found, Russian officials say.
It is the first “black box” to be found from the Tu-154 jet, which came down with the loss of all 92 passengers and crew.
The plane crashed soon after take-off from an airport near the city of Sochi.
It was carrying artistes due to give a concert for Russian troops in Syria, along with journalists and military.
The search for victims’ bodies is continuing, with one unofficial report on Tuesday saying the remains of 16 people had been found so far.
The plane disappeared from radar two minutes after taking off from Sochi’s Adler airport at 05:25 (02:25 GMT) on Sunday, heading for Latakia in Syria, the defence ministry said.
The flight had originated in Moscow and landed in Sochi for refuelling.
It was carrying 64 members of the famed Alexandrov military music ensemble, as well as one of Russia’s best-known humanitarian figures, Yelizaveta Glinka, known as Dr Liza, executive director of the Fair Aid charity.
The Alexandrov Ensemble had been scheduled to perform a New Year’s concert at Russia’s Hmeimim air base near Latakia.
Russia has been carrying out air strikes in support of Syrian government forces who are battling rebels opposed to Syrian President Bashar al-Assad.
The flight data recorder was found by a Seaeye Falcon underwater remotely operated vehicle at a depth of 17m (56ft), 1,600m from the shore, the Russian defence ministry told Russia’s Ria-Novosti news agency.
An unnamed source involved in the search told another news agency, Interfax, that the recorder had been taken to the surface, and that “visually, it is in good condition”. It would be taken to Moscow later on Tuesday for examination.
According to the same source, the location of a second black box had also been established and it could be recovered shortly.
There have been few clues as to the cause of the crash although Transport Minister Maxim Sokolov has played down the possibility of a bomb attack.
He reiterated that investigators were looking into whether pilot error or a technical fault might have brought down the aircraft.
A source close to the investigation told Interfax the plane may have been overloaded.
“Witness accounts and other objective data obtained during the investigation suggest the plane was unable to gain height and for some reason – possibly overloading or a technical fault – crashed into the sea,” the unnamed source said.
According to an Aviation Safety Net report, the plane made a U-turn back towards the coastline shortly after take-off, before disappearing off the radar.
But audio recording played on Russian media and said to be of the final conversation between air traffic controllers and the plane reveals no sign of any difficulties.
Voices remain calm until the plane disappears and the controllers try in vain to re-establish contact.
The Tupolev airliner involved in the crash was an old model no longer flown by air lines in Russia but still used by the military. It was 33 years old.