A plane crash near Moscow on Sunday which killed all 71 people on board may have occurred because its speed sensors were iced over.
As a result, instruments on the aircraft’s control panel could have shown the pilots the wrong speed data, the TASS news agency quoted investigators as saying.
The AN-148 passenger plane was en route from Moscow to the Russian provincial city of Orsk and was operated by Russia’s Saratov Airlines.
A special commission has been ordered by President Vladimir Putin to investigate what caused the crash.
The plane’s crew sent no distress signals and debris and human remains are spread over the radius of a kilometre around the crash site.
The plane, manufactured in 2010, had been carrying 65 passengers and six crew. The passenger list showed many young people were on board, including a five-year-old girl.
Elena Voronova, a spokeswoman for Saratov Airlines, said there had been no concerns about the technical condition of the plane, which went into service with her company in 2016.