air gap, mid-Atlantic

air gap, mid-Atlantic, area south of Greenland in which Allied convoys could not be given air cover against U-boat attacks during much of the battle of the Atlantic (see Map 1). It was therefore ideal for the operation of Admiral Dönitz's wolf-packs, though aircraft launched from merchant ships (see CAM ships, fighter catapult ships, and MAC ships), and later escort carriers, were used to try to cover it. Until May 1941 air cover was very limited but from that month land-based aircraft began operating 965 km. (600 mi.) eastwards from Newfoundland, 645 km. (400 mi.) southwards from Iceland, and 1,125 km. (700 mi.) westwards from Northern Ireland. However, this still left a 480 km. (300 mi.) gap south of Greenland where merchant shipping losses continued to be high. A decision at the Casablanca conference in January 1943 (see SYMBOL) to cover this with additional very long range Liberator bombers was not implemented as they were badly needed for use in the Pacific war and the strategic air offensive against Germany. However, a recommendation by the Washington Convoy conference, held in March 1943, that 20 be supplied to the Royal Canadian Air Force to cover the gap, was heeded, and by the end of May sufficient were operating to close it.

Until January 1943, there was also a gap east of the Azores, which affected the Gibraltar and West African convoys, another west of the Azores, and another in the South Atlantic. The one west of the Azores was called the ‘Black Pit’ by the Germans because they sank so many ships there, but it was eventually closed when air bases in the Azores were opened in October 1943.