The Hump was the name given by Allied pilots in the Second World War to the eastern end of the Himalayan Mountains over which they flew military transport aircraft from India to China to resupply the Chinese war effort of Chiang Kai-shek and the units of the United States Army Air Forces (AAF) based in China. Creating an airlift presented the AAF a considerable challenge in 1942: it had no units trained or equipped for moving cargo, and no airfields existed in the China Burma India Theater (CBI) for basing the large number of transports that would be needed. Flying over the Himalayas was extremely dangerous and made more difficult by a lack of reliable charts, an absence of radio navigation aids, and a dearth of information about the weather.