The group was activated as the 521st Air Defense Group once again in 1953, when Air Defense Command (ADC0 established it as the headquarters for a dispersed fighter-interceptor squadron and the medical, aircraft maintenance, and administrative squadrons supporting it. It was replaced in 1955 when ADC transferred its mission, equipment, and personnel to the 53d Fighter Group in a project that replaced air defense groups commanding fighter squadrons with fighter groups with distinguished records during World War II.
World War II
The group was first activated as the 521st Air Service Group in a reorganization of Army Air Forces (AAF) support groups in which the AAF replaced service groups that included personnel from other branches of the Army and supported two combat groups with air service groups including only Air Corps units. It was designed to support a single combat group.[1] Its 947th Air Engineering Squadron[2] provided maintenance that was beyond the capability of the combat group, its 771st Air Materiel Squadron[3] handled all supply matters, and its Headquarters & Base Services Squadron provided other support.[1] The group supported 310th Bombardment Group in Italy.[4] The group returned to the US in 1945 and was inactivated. It was disbanded in 1948.[5]
Cold War
F-51D as flown by the 87th FIS until 1953
The group was reconstituted, redesignated as the 521st Air Defense Group, and activated at Sioux City Municipal Airport in 1953[6] with responsibility for air defense of central Midwestern United States. It was assigned the 87th Fighter-Interceptor Squadron (FIS), which was already stationed at Sioux City Airport, and flying World War II era North American F-51 Mustangs[7] as its operational component.[8][9] The 87th FIS had been assigned directly to the 31st Air Division.[9] The group replaced the 79th Air Base Squadron as the host USAF unit at Sioux City Municipal Airport. It was assigned three squadrons to perform its support responsibilities.[10][11]
Buss, Lydus H.(ed), Sturm, Thomas A., Volan, Denys, and McMullen, Richard F., History of Continental Air Defense Command and Air Defense Command July to December 1955, Directorate of Historical Services, Air Defense Command, Ent AFB, CO, (1956)
Coleman, John M (1950). The Development of Tactical Services in the Army Air Forces. New York, NY: Columbia University Press.