1963    Joe Walker flies a North American X-15 to a record altitude of 106,010 metres (347,800 feet) on X-15 Flight 90. Exceeding an altitude of 100 km, this flight qualifies as a human spaceflight under international convention.

1963    American Joe Walker in an X-15 test plane reaches an altitude of {{convert|106|km|mi|abbr=on|lk=off}}.

1966    One of the XB-70 Valkyrie prototypes is destroyed in a mid-air collision with a F-104 Starfighter chase plane during a photo shoot. NASA pilot Joseph A. Walker and United States Air Force test pilot Carl Cross are both killed.