Russian investigators looking into the crash believe a fault with its wing flaps was the reason it plunged into the Black Sea.
The Interfax news agency separately cited an unnamed investigative source as saying preliminary data showed the wingflaps had failed and not worked in tandem.
The Life-dot-ru news portal, which has close contacts with law enforcement agencies, said it had obtained a readout of one of the pilot's last words.
It indicates a problem with the wing flaps. There was no official confirmation of the readout.