The fastest a human has ever flown remains the record set by the North American X-15 experimental rocket-powered aircraft. On October 3, 1967, pilot William J. Knight achieved a staggering speed of Mach 6.70, which is approximately 4,520 mph (7,274 km/h). This record-breaking flight took place at an altitude of 102,100 feet, where the X-15 reached its peak velocity. In 2026, while modern supersonic and hypersonic programs like the Darkstar or the SR-72 are in development, the X-15's manned speed record remains the gold standard for atmospheric flight. This velocity is so intense that the aircraft's skin had to be constructed from Inconel X, a nickel-chromium alloy, to withstand the extreme frictional heat. For comparison, a standard commercial airliner cruises at about Mach 0.85, meaning the X-15 flew nearly eight times faster than a Boeing 777. While the Space Shuttle reached higher speeds during re-entry (approx. Mach 25), the X-15 holds the title for the fastest flight of a powered aircraft within the Earth's atmosphere.