 RL @-@ 201 first flew on 25 March 1958 with Chief Development Test Pilot S / L Janusz Żurakowski at the controls . Four more J75 @-@ powered Mk 1s were delivered in the next 18 months . The test flights , limited to " proof @-@ of @-@ concept " and assessing flight characteristics , revealed no serious design faults . The CF @-@ 105 demonstrated excellent handling throughout the flight envelope , a large part due to the natural qualities of the delta @-@ wing , but responsibility can also be attributed to the Arrow 's Stability Augmentation System . The aircraft went supersonic on its third flight and , on the seventh , broke 1 @,@ 000 mph ( 1 @,@ 600 km / h ) at 50 @,@ 000 ft ( 15 @,@ 000 m ) while climbing . A top speed of Mach 1 @.@ 98 was achieved , and this was not at the limits of its performance . However , an Avro report made public in 2015 clarifies that during the highest speed flight , the Arrow reached Mach 1 @.@ 90 in steady level flight , and an indicated Mach number of 1 @.@ 95 was recorded in a dive . Estimates up to Mach 1 @.@ 98 likely originated from an attempt to compensate for lag error , which was expected in diving flight . 
