HUMAN error may be to blame for a plane crash that killed 71 people, as investigators said the plane’s pilots failed to turn on the heating unit for its measuring equipment, resulting in flawed speed data.

After studying the An-148’s flight data recorder, the Interstate Aviation Committee said Sunday’s crash near Moscow occurred after the pilots saw conflicting data on the plane’s two air speed indicators.

The flawed readings came because the pilots failed to turn on the heating unit for the plane’s pressure measurement equipment prior to take-off, the committee said.

The pilots had placed the An-148 on autopilot after taking off from Moscow’s Domodedovo Airport but took its manual controls back when they heard alarm signals warning of conflicting speed data.

One indicator showed the plane’s speed at zero, investigators said.

The pilots then performed a series of manoeuvres and eventually took the plane into a dive at 30-35 degrees.

It plummeted into a snowy field outside Moscow six minutes after take-off, killing all 65 passengers and six crew.

The committee emphasised that the flawed speed data resulted from the “icing of pressure measurement instruments that had their heating systems turned off”.

Earlier reports indicated the plane’s captain had chosen not to have the plane undergo de-icing before takeoff.