McKennon entered the U.S. Army Air Corps in early 1941 hoping to become a pilot but was refused because of insufficient aptitude.

In November 1942, he was transferred back to the United States Army Air Force with the rank of second lieutenant.

McKennon quickly proved his worth as a fighter pilot, shooting down four enemy aircraft while flying the P-47 Thunderbolt.

His group then transitioned to the P-51 Mustang, in which on March 6, 1944,[2] he downed a fifth enemy plane and earned his designation as an ace.

The two pilots disposed of their parachutes to make room, and McKennon flew back to Debden sitting on Green's lap.