The US Air Force has successfully fired an X-51A Waverider hypersonic cruise missile from a B-52 Stratofortress. The missile accelerated to Mach 6 before splashing down in the Pacific Ocean.

The air force said the test flight of the X-15A Waverider lasted more than 200 seconds, the longest ever hypersonic flight powered by scramjet propulsion.

The previous record was 12 seconds in a NASA X-43 vehicle.