B-17 Flying Fortress units of the United States Army Air Forces 2d Bombardment Group, Langley Field, Virginia on 11 January 1936; the first production B-17B was delivered on 29 March 1939 also to the 2nd Bombardment Group. A total of 12,677 production Fortresses was built before production came to an end. In August 1944, the Boeing B-17 equipped no less than 33 overseas combat groups. The last Boeing-built B-17G was delivered to the USAAF on 13 April 1945. Following the end of World War II, the Flying Fortress was rapidly withdrawn from USAAF service, being replaced by the B-29 Superfortress. Literally thousands of Fortresses used in combat in Europe by Eighth
RAF Bomber Command aircrew of World War II air gunner to man the mid-upper gun turret although sometimes the gunners would agree to exchange turrets. At the outbreak of war in September 1939 operational Royal Air Force bomber squadrons in Europe were equipped with two main categories of bombers, single-engined Fairey Battle and twin-engined Bristol Blenheim light bombers and Armstrong Whitworth Whitley, Vickers Wellington and Handley Page Hampden medium bombers. Bomber Command aircrew "trades" flying operationally in the early stages of the war were: Pilot – A qualified pilot flew the aircraft and in the Royal Air Force was usually the captain (function not rank) of the crew,