Authorized as No. 20 (Bomber) Squadron (Auxiliary) at Regina, Saskatchewan on 1 June 1935, the unit commenced flying training in April 1937 when it received four Moth aircraft. It was renumbered No. 120 Squadron on 15 November 1937. Called out on voluntary full-time duty in September 1939, and redesignated Bomber Reconnaissance on 31 October, the squadron flew Delta, Hudson, Stranraer, Canso A and Catalina aircraft on West Coast anti-submarine duty until disbanded at Coal Harbour, British Columbia on 1 May 1944.
First Mission: 30 June 1940, Delta'675 frorn Sea Island with F/0 M.P. Fraser and crew - patrol and search over Juan de Fuca Strait. (Although the squadron was to fly a total of 18 patrols in June and July 1940 (9 for the Department of Fisheries), it did not commence regular patrols until 11 December 1941, after Japan had entered the war. On that day, Stranraer 950 from Coal Harbour with F/L Addington and crew flew a recon- naissance patrol.)
Last Mission: 21 April 1944, Cgtalina JX571 from Coal Harbour with FS I.A.H. McFariane and crew - patrol.