 During tests, the pressure was reduced to the equivalent of being at an altitude of 80,000 ft.In early 1936, the airframe was completed; on 11 May 1936, the Type 138A was flown for the first time, powered by a standard Pegasus IV which drove a three-bladed propeller.For this maiden flight, it was piloted by Cyril Uwins, Bristol's chief test pilot, who had previously flown the Vickers Vespa on its world record flight.