First Lieutenant Oliphant was the pilot of a B-26C Invader bomber with the 13th Bomber Squadron, 3rd Bomber Wing. On 2 September 1951, while on a night intruder mission, his aircraft was hit by anti-aircraft fire and crashed. He was listed as Missing in Action and was presumed dead on 31 December 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Oliphant was awarded the Air Medal with Oak Leaf Cluster, 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.