Failure to de-ice a UTair plane before takeoff was the most likely cause of a crash in Siberia that killed 31 people, federal investigators said Wednesday.
The twin turboprop ATR 72-200 craft, carrying 43 people, tilted to its right side and then sharply left as it crashed shortly after takeoff from Tyumen in western Siberia on Monday.
"At the moment, on the basis of the materials received, the investigators consider the failure to conduct a de-icing procedure to be the most probable cause of the air crash," Russia's Investigative Committee said on its website.
Statements from those responsible for de-icing the plane and video evidence from the airport's surveillance systems supported the suspicion. UTair officials declined immediate comment.
The head of Russia's Federal Air Transportation Agency, Alexander Neradko, had also said earlier that the plane had not been de-iced properly.
Federal investigators said the plane had 35,000 flying hours since going into operation in 1992 and had not had a "serious" technical check since 2010.