American test pilot and astronaut (1921-1966) who was killed when his F-104 Starfighter chase plane collided with an XB-70 Valkyrie; Walker had been flying in a tight group formation for a publicity photo, and was knocked out of control by the supersonic bomber's wake. Commemorative cover with a cachet honoring the X-15 program, signed under the cachet in black ink by Walker. In fine condition, with pencil notation along bottom edge affirming his “astronaut” status for his 66.75 NM flight in 1963. RRAuction COA.
