Intensive discussions between Avro and the RCAF examined a wide range of alternative sizes and configurations for a supersonic interceptor, culminating in RCAF Specification AIR 7-3 in April 1953. AIR 7-3 called specifically for a two crew, twin engine, aircraft with a range of ) for a normal low-speed mission, and for a high-speed interception mission. It also specified operation from a runway; a Mach 1.5 cruising speed at an altitude of ; and manoeuvrability for 2 "g" turns with no loss of speed or altitude at Mach 1.5 and . The specification required five minutes from starting the aircraft's engines to reaching altitude and Mach 1.5. It was also to have turn-around time on the ground of less than . An RCAF team led by Ray Foottit visited US aircraft producers and surveyed British and French manufacturers before concluding that no existing or planned aircraft could fulfill these requirements.