Lieutenant Junior Grade Koch was the pilot of a F4U-4 Corsair fighter with Fighter Squadron 874 aboard the carrier USS Bon Homme Richard (CV-31). On 11 August 1951, after making a dive on a bridge target in North Korea, his aircraft was leveling off when its wing fell off and it exploded. He was listed as Missing in Action and was presumed dead on 21 May 1954. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

For his leadership and valor, Lieutenant Junior Grade Koch was awarded the Distinguished Flying Cross, the Purple Heart, the Combat Action Ribbon, 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.