Speed sensors that were iced over may have caused a passenger jet to crash near Moscow, killing all 71 people on board, investigators say.
The faulty instruments could have given the pilots wrong speed data, Russia's Interstate Aviation Committee said.
The Saratov Airlines jet went down minutes after take-off from Moscow's Domodedovo airport on Sunday.
More than 1,400 body parts and hundreds of plane fragments have been recovered from the crash site.
A preliminary analysis of the on-board flight recorder indicated the plane had problems two-and-a-half minutes after it took off, at an altitude of around 1,300m (4,265ft).
The instruments began displaying different speed readings, probably because of iced speed sensors while their heating systems were shut off, the committee said.
When the crew detected the issue, they switched off the plane's autopilot. They eventually took the plane into a dive at 30-35 degrees.
