Flight 153 of the North American X-15 was a test flight conducted by NASA and the US Air Force in 1965. Piloted by Joe H. Engle it reached an altitude of 81.1 km. October 14, 1965 at 20:47 UTC · Launch Successful North American X-15 — United States Air Force, to Suborbital Edwards Air Force Base, Air launch to Suborbital flight Crew: Joe Engle Program: X-15 Data: Launch Library 2, The Space Devs. Image via The Space Devs.