X-15 in flight

The X-15A-3 rocket plane flies over Edwards Air Force Base during a mission in the 1960s. The aircraft crashed in 1967, killing pilot Maj. Michael J. Adams. According to a NASA report, the X-15A-3 crashed "due to a stable, albeit non-robust adaptive controller." The U. S. Air Force Test Pilot School recently validated a much more robust adaptive controller which was built by a team at the University of Illinois Champaign Urbana. The controller is designed to adapt to any fly-by-wire aircraft. (Archive photo courtesy of NASA)