Yeager had been the first rocket pilot to go through this particular hole in the supersonic envelope, and it was during the flight in the X–IA in which he set a speed record of Mach 2.42. He was battered unconscious and fell seven miles before hitting the denser atmosphere at 25,000 feet and coming to and managing to put the ship into a spin. That was good; a mere spin he knew how to get out of, and he survived.
