later becoming Assistant Chief of the Manned Spacecraft Operations Branch. White was designated the Air Force's primary pilot for the North American X-15 program in 1958. While the new plane was undergoing its initial tests, he attended the Air Command and Staff College at Maxwell Air Force Base, Alabama, graduating in 1959. He made his first test flight of the X-15 on April 15, 1960, when the aircraft was fitted with two interim, 16,000 lbf (71 kN) XLR-11 thrust rocket engines. Four months later, he flew to an altitude of 136,000 feet (41.5 km) above Rogers Dry Lake. White would have participated in the Air Force's Man In Space Soonest program, had it come to fruition. In February 1961, White unofficially set a new air speed record when he flew the X-15 at a speed of 2,275 mph (3,660 km/h), following the installation of a 57,000 lbf (254 kN) thrust XLR-99 engine. White was the first human to fly an aircraft at Mach 4 and later Mach 5 over the next eight months. On November 9, 1961, White flew the X-15 at 4,093 mph (6,590 km/h), making him the first pilot to fly a winged craft at six times the speed of sound (Mach 6). President John F. Kennedy used the occasion to confer the most prestigious award in American aviation, the Robert J. Collier Trophy, jointly to White and three of his fellow X-15 pilots: NASA's Joseph A. Walker, Commander Forrest S. Petersen of the U.S. Navy, and North American Aviation test pilot Scott Crossfield. A day later, Air Force Chief of Staff General Curtis E. LeMay awarded White his new rating as a Command Pilot Astronaut. On July 17, 1962, Major White flew the X-15 to an altitude of 314,750 feet (59 miles, 96 km). This qualified him for USAF astronaut wings, becoming the first "winged" astronaut, and one of a few who have flown into space without a conventional spacecraft. Major Bob White was featured with a cover story in the August 3, 1962, issue of Life magazine, detailing his July 17 flight. Pilot Robert White commented on his high altitude X-15 flights: My flights to 217,000 feet [66 km] and 314,750 feet [96 km] were very dramatic in revealing the Earth's curvature ... at my highest altitude I could turn my head through a 180-degree arc and wow!—the Earth is really round. At my peak altitude