As workers continue to scour the wreckage of Sunday's plane crash near Moscow, investigators say human error may be to blame.
It's thought the pilots failed to enable the heating of pressure sensors before taking off, which caused wrong speed data to be displayed.
Crew members then turned off the autopilot and the plane began to lose speed until it crashed.
The Saratov Airlines jet went down minutes after taking off from Moscow's Domodedovo airport, which was travelling to Orsk in the Ural Mountains.
All 71 people on board were killed, with no emergency call from the crew.
More information is expected when the cockpit voice recorder is examined.
More than 700 people have helped search the crash site, which was expanded to thirty hectares on Monday.
Vigils were held in Moscow and Orsk on Monday evening to remember the victims of the crash.