Knettishall was built to Class A standard for an American Bomb Group that would be bringing up to forty heavy bombers with them in three or four Squadrons. The 388th Bomb Group, which stayed at Knettishall for their entire service in the ETO, flew B-17 Flying Fortresses on missions over occupied Europe. The Group also sent the 560th Bomb Squadron to Fersfield to fly Aphrodite missions. This involved crews flying full-loaded but worn-out B-17s to the edge of the British mainland before baling out and allowing a crew in another aircraft to radio-control the B-17 into the intended target. On one occasion the crew were unable to control the B-17 and it crashed at Sudbourne Park, Suffolk, leaving a crater 100 feet across.