Faulty speed data due to human error is reportedly to blame for the passenger plane crash outside Moscow that killed 71 people on Sunday.

The Saratov Airlines Flight 703 on Sunday plunged to the ground minutes after taking off from Domodedovo Airport.

Emergency workers have recovered two black boxes, nearly 1,500 body parts and hundreds of plane fragments from the crash site.

Flight recorder data shows faulty speed readings ahead of the crash, possibly because the pilot had failed to activate heating for pressure measurement equipment and the plane’s sensors had frozen over, the Interstate Aviation Committee said Tuesday in an online statement, cited by Russian media.