[ adj ] (of speed) less than that of sound in a designated medium <adj.all> aircraft flying at subsonic speeds
The spokesman did, however, describe the jet as being capable of flying in the "high subsonic range," or about 600 mph.
That's a huge problem: Used to locate incoming aircraft at the highest altitudes and longest ranges, such radars are precisely what the giant, subsonic B-2 was designed to foil.
Develop larger subsonic jets of up to 1,000 seats for heavily traveled routes, supersonic commercial transports for international routes, and short-haul aircraft and miniports at suburban locations for transfer purposes.
Returnees limp home on scheduled subsonic flights.
Now, Nasa has joint programmes with the US aircraft industry on both supersonic and advanced subsonic airliners expected to enter service early in the next century.