Airman First Class Kingsbury was a crew member of a B-29A Superfortress Bomber with the 93rd Bomber Squadron, 19th Bomber Wing. On 29 March 1951, while on a combat mission, his aircraft lost two engines over the East China Sea, northwest of Okinawa. He was listed as Missing in Action and was presumed dead on 18 December 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Kingsbury was awarded the Air Medal, 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.