Which of the following is a key characteristic of a supersonic aircraft?

A key characteristic of a supersonic aircraft is its ability to fly faster than the speed of sound. This characteristic distinguishes supersonic aircraft from subsonic ones, which operate at speeds below the sound barrier, typically defined as Mach 1 (approximately 767 mph or 1,235 km/h at sea level). Supersonic flight allows these aircraft to reduce travel time significantly compared to conventional aircraft.

In contrast, the other options highlight attributes that do not capture the essence of supersonic flight. For instance, the ability to fly below the speed of sound describes subsonic aircraft, while the requirement for longer runways for takeoff is more relevant to heavy or specialized aircraft rather than being a defining feature of supersonic performance. Additionally, while some supersonic aircraft may utilize jet engines, they are not restricted to propeller engines exclusively, as several supersonic designs prioritize jet propulsion to achieve the high speeds required.