North American Aviation developed the X-15 for a program seeking to investigate winged flight and human performance at the edge of space. Pioneering research that would benefit every subsequent U.S. human spaceflight program, three X-15’s made 199 flights. On Nov. 15, 1967, U.S. Air Force Major Mike Adams was scheduled to fly the X-15 on its 191st flight. Major Adams was a skilled and experienced test pilot, and the team expected another successful mission. But when an electrical disturbance coursed through the aircraft, the flight control system was degraded at an unforgiving instant. Major Adams entered history’s first hypersonic spin, followed by an inverted dive. Massive g forces from these events incapacitated him, leaving him unable to eject before the aircraft broke apart high above the desert. A lack of component qualification testing, a degraded flight control system, possible pilot vertigo and misreading a single, deceptive flight instrument all led to departure from controlled flight. This month, we honor Major Adams’ memory by considering this story, especially as designers conceive new commercial vehicles to fly passengers to the edge of space and back again.