The squadron was activated in April 1943 as the 638th Bombardment Squadron at Key Field, Mississippi, as one of the original squadrons of the 408th Bombardment Group. In August, along with several other Army Air Forces single engine dive bomber units, it became a fighter-bomber unit, and was designated as the 520th Fighter-Bomber Squadron. The squadron did not receive aircraft to begin training until October, after it had moved to Drew Field, Florida. It served as an operational training unit with various aircraft, providing cadres to "satellite groups" and as a replacement training unit, training individual pilots. However, the AAF was finding that standard military units, based on relatively inflexible tables of organization, were not proving well adapted to the training mission. Accordingly, it adopted a more functional system in which each AAF base was organized into a separate numbered unit. In this reorganization the squadron was disbanded in 1944 as the AAF converted to the AAF Base Unit system and was replaced, along with other units at Woodward Army Air Field, by the 267th AAF Base Unit in a reorganization of the AAF in which all units not programmed for deployment overseas were replaced by AAF Base Units to free up manpower for assignment overseas.
During the Cold War the squadron was reconstituted in December 1954. At this time, it was redesignated as the 520th Fighter-Interceptor Squadron and activated at Geiger Field, Washington, where it was assigned to the 530th Air Defense Group. At Geiger, the squadron flew airborne intercept radar equipped and Mighty Mouse rocket armed North American F-86D Sabre aircraft. The 530th Group was inactivated and replaced by the 84th Fighter Group in 1955 as part of Air Defense Command's Project Arrow, which was designed to reestablish fighter units that had compiled memorable records in the two world wars. The squadron was inactivated along with the group and its equipment and personnel were transferred to the 498th Fighter-Interceptor Squadron, which was simultaneously activated.
Lineage
Constituted as the 638th Bombardment Squadron on 23 March 1943
Reconstituted and redesignated 520th Fighter-Interceptor Squadron on 4 November 1954
Assignments
408th Bombardment Group, 5 April 1943 – 1 April 1944
530th Air Defense Group, 8 December 1954 – 18 August 1955