 On 5 April 1943, the 396th Bombardment Group became a second OTU at the base, providing first phase heavy bomber training for the B-17 Flying Fortress with its 592d, 593d, 594th and 595th Bombardment Squadrons.The first flight of the XB-47 took place on 17 Dec. 1947, originating at Boeing Field and terminating at Moses Lake Air Force Base.In Feb. 1949, a B-47 took off from Larson, headed east and "broke all coast-to-coast speed records" with an average speed of 607.8 miles per hour.