Royal Air Force No. 131 OTU (Operational Training Unit) formed at RAF Killadeas, Co. Fermanagh in July 1942 as part of No. 15 Group Coastal Command.
Royal Air Force No. 5 OTU (Operational Training Unit) flew Bristol Beaufort, Handley-Page Hampden, and Lockheed Hudson bombers from RAF Long Kesh, Co. Down.
Royal Air Force No. 7 OTU (Operational Training Unit) was a Coastal Command outfit flying Vickers Wellington bombers from Limavady, Co. Londonderry.
Between December 1942 and May 1943, RAF 228 Squadron spent time at RAF Castle Archdale, Co. Fermanagh where they sustained the loss of one Sunderland.
On 1st December 1943, RAF 290 Squadron formed at Newtownards Airfield, Co. Down. In March 1944, their Hawker Hurricane unit moved to Long Kesh, Co. Down.