Major William J. Knight, U.S. Air Force, with the modified X-15A-2, 56-6671, at Edwards Air Force Base, California. Knight is wearing a David Clark Co. MC-2 full-pressure suit with an MA-3 helmet. (U.S. Air Force)
On Oct. 3, 1967, Maj. William “Pete” Knight flew the modified X-15A-2 to its maximum speed of Mach 6.7 or 4,520 mph, a speed which remains the fastest anyone has ever flown an aircraft. (U.S. Air Force photo)