On 21 October 1942 Sayer departed from RAF Acklington in a Hawker Typhoon to carry out tests of a gunsight involving gun firing into Druridge Bay Ranges, accompanied by another Typhoon. Neither aircraft returned, and it was assumed that they collided over the bay. He was replaced as Gloster's test pilot by Michael Daunt, who would be the first to fly the Gloster Meteor (powered by two de Havilland Goblin engines designed by Frank Halford) on 5 March 1943 at RAF Cranwell.