Captain Haythorne was the pilot of a F-51D Mustang night fighter with the 40th Fighter-Interceptor Squadron, 35th Fighter-Interceptor Group. On 11 February 1951, while on a combat mission, his aircraft received a direct hit by anti-aircraft fire. He bailed out over water but died of wounds he received.

Haythorne was awarded the Purple Heart, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.