With the closure of the Burma Road by Japanese advances in Southeast Asia, Chiang Kai Shek was cut off from the vital supplies that were needed to keep China in the war. The only way to supply the Chinese until the Burma Road could be reestablished was via air. To this end the US Army Air Corps’ Corps Ferrying Command (the predecessor to today’s Air Mobility Command) created the India-China Ferry from Assam in Eastern India to Kunming in China. 
The 720 mile trip was the last leg of a 14,000 mile journey from the United States. For example if Chiang needed Widget A, it would be loaded in New Orleans, or later Los Angeles, for the two month trip via convoy to Karachi. From there it would take two months across northern India’s primitive road network or by barge on its rivers to Assam where it was loaded onto requisitioned propeller driven DC-3 cargo planes (or C-46/47s in later years). The pilots would then fly the dangerous route over the Naga Hills of Burma, named for the headhunting tribes that inhabited the “hills” that were hills only in comparison to the Himalayan Mountains (most were larger and more jagged than the Rockies) further on. Then it was over the proper Himalayan mountains to Southern China. The harrowing trips with numerous sharp turns were without charts, by dead reckoning, with unpredictable weather, through violent winds at altitudes as high as 15,000 ft above sea level and with no hope rescue if they crashed.

The first India-China ferry flight of two former Pan Am planes on 8 April 1942 was not actually over the specific part of the trip known as, “The Hump”, that would only come in May after the Japanese captured the Myitkyina airfield which forced the route over the Sansuny Range to avoid Interception. Ironically it didn’t carry supplies for China but for America. The flight carried eight thousand gallons of aviation fuel for use by the Doolittle Raiders who were optimistically expected to land on Chinese airfields after their raid on Japan. 
The first month only brought 146 tons to China. But until they stopped in November 1945, the unescorted trips over The Hump brought 685,000 tons of supplies to China at the cost 594 planes lost to crashes or Japanese fighters. That’s at least one missing presumed dead crew every other day for the rest of the war. Chiang Kai Shek attributed their dedication in the face of such adversity as one of the reasons China stayed in the war. By the end of the war, one aircraft was taking off for China from India over the Hump every three minutes.