The voice recorder of the ill-fated Russian passenger plane has been found among the wreckage.
Workers have been searching for clues about Sunday's crash near Moscow, which killed all 71 people on board.
Russian media reports vastly different speed measurements were received by the cockpit just after take-off.
The pilots reportedly got into an argument as they tried to solve the problem before increasing their speed and tilting the plane towards the ground.
Black box data suggests the pilots failed to turn on the heating of their pressure measurement equipment before take off, despite the procedure being listed on a preflight checklist. This caused the device to ice over.
The Saratov An-148 aircraft plummeted into a snowy field 6 minutes after leaving Moscow's Domodedovo Airport on Sunday, which was heading to Orsk in the Ural Mountains.
More than 1,400 body parts and hundreds of plane fragments have so far been recovered from the crash site.