This week in Edwards flight test history Published March 8, 2017 412th Test Wing Public Affairs EDWARDS AIR FORCE BASE, Calif. -- On March 10, 1959, the first of four captive-carry flights of the X-15 mated to its Boeing NB-52A Stratofortress “mother ship” (s/n 52-003A) took place. North American Aviation test pilot A. Scott Crossfield was in the cockpit of the X-15.