A US Air Force pilot spent 50 minutes on a conference call with engineers before his F-35 fighter jet crashed and exploded earlier this year.

The pilot joined the call with five engineers from Lockheed Martin, the manufacturer, shortly after take-off on Jan 28, an air force accident report said. 

Freezing temperatures had ruptured his aircraft’s hydraulic lines and main landing gears.

The pilot suffered an “in-flight malfunction” but was able to safely eject before the $200m (£149m) F-35 Lightning II jet plummeted to the tarmac below and erupted in flames at US Eielson Air Force Base, Fairbanks, south-east Alaska.

Video showed the pilot parachuting slowly to the ground as a fireball rose from the wreckage. He was taken to Bassett Army Hospital.