Airman Larsen was a crew member of a patrol bomber PB-5M Catalina with Patrol Squadron 46. He was listed as Missing in Action while participating in aerial support over Korea on 5 November 1950. He was presumed dead on 29 March 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Larsen was awarded 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.