The unifying characteristic of the Century Series aircraft was advanced performance and avionics when they were introduced. The F-100 was the first aircraft in the USAF capable of exceeding the speed of sound in level flight. The F-101 was the first aircraft in the USAF capable of exceeding 1,000 mph (1,600 km/h). The F-102 was the first aircraft in the world to utilize area rule in its design. The F-104 was the first combat aircraft capable of Mach 2 flight, and the only aircraft in history to simultaneously hold the world speed and altitude records. Three of the Century Series aircraft—F-101, F-102, and F-106—were armed with nuclear air-to-air missiles. These weapons, designed to destroy incoming nuclear-armed Soviet bombers even when not scoring a clear hit (due to the nuclear explosion radius, shock wave and radiation burst), were the only nuclear weapons in USAF arsenal at the time to be under sole control of their pilots (during a mission).