Plane debris has been dragged from the Black Sea in a huge recovery operation after Sunday's crash.
Russian officials declared the investigation is now focusing on technical faults or a pilot error.
All 84 passengers and eight crew on the Russian military's Tu-154 plane when it crashed two minutes after taking off from the southern city of Sochi en route to Syria.
More than 3,500 people on 45 ships - including 135 divers from across Russia - have been sweeping a vast crash site in the Black Sea and along the shore, according to the Defense Ministry.
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