Creating an airlift presented the USAAF a considerable challenge in 1942: it had no units trained or equipped for moving cargo, and there were no airfields in the China Burma India Theater (CBI) for basing the large number of transport aircraft that would be needed.

It procured most of its officers, men, and equipment from the USAAF, augmented by British, British-Indian Army, Commonwealth forces, Burmese labor gangs and an air transport section of the Chinese National Aviation Corporation (CNAC).

[10][b] Chinese Air Force Major General Mao Bangchu was tasked with leading the exploration of suitable air-routes over the dangerous Himalayas in 1941,[11] and CNAC pilot Xia Pu recorded the first flight from Dinjan, India, to Kunming, China, during November of that year in what was to become the route now known as "the Hump".

[12] On 25 February 1942, President Roosevelt wrote to General George C. Marshall that "it is of the utmost urgency that the pathway to China be kept open", and committed ten C-53 Skytrooper transports for lend-lease delivery to CNAC to build its capability to 25 aircraft.

[13] When the newly created Tenth Air Force opened its headquarters in New Delhi under the command of Maj. Gen. Lewis H. Brereton in March 1942, it was assigned the responsibility of developing an "India-China Ferry" using both U.S. and Chinese aircraft.

Flying from the Royal Air Force airfield at Dinjan, Lt. Col. William D. Old used a pair of the former Pan Am DC-3s to ferry 8,000 U.S. gallons (30,000 liters) of aviation fuel intended to resupply the Doolittle Raiders.

The ABC Ferry Command resupplied Stilwell's retreating army and evacuated its wounded, while establishing a regular air service to China using ten borrowed DC-3s, three USAAF C-47s,[18][26] and 13 CNAC C-53s and C-39s.

The group was activated in India in March without personnel or equipment and was assigned to the operational control of the Tenth Air Force over the objections of the commander of ATC, who feared that its planes and crews would be steered into combat units, which did in fact occur at times.

[34] Aircraft continued to arrive in small increments through October with flight crews consisting of airline pilots holding Air Corps Reserve commissions who had been called up for active duty specifically for the India-China assignment, and navigators, engineers and radiomen from the USAAF technical training schools.

The India Air Task Force had flown reconnaissance missions over the captured airfield at Myitkyina all summer, but the Japanese mounted the raids from Lashio or bases in southern Burma, equipping their fighters with external fuel tanks.

[59][t] Living conditions for airlift flight crews and support personnel, particularly at Dinjan, were described as "by far the worst in the entire theater",[60] with primitive quarters, poor sanitation, bad food and mess facilities, pervasive disease, and lack of recreation.

In June, although the British—and later the U.S. Army's Services of Supply—failed to complete construction of all-weather runways at Mohanbari and Sookerating,[72] the activation of the 28th,[z] 29th,[aa] and 30th[ab] Transport Groups proceeded, an attempt to expand the C-46's role to meet projected levels of tonnage.

[80] Japanese pilots referred to the shooting down of vulnerable transport aircraft as tsuji-giri ("cutting down a casually met stranger") or akago no te wo hineru ("twisting a baby's arm").

Japanese interceptors blocked use of eastbound routes at lower altitudes and the C-54s were limited for the time being to freight movement within India or flights between the CBI and the continental United States.

[3] Tunner and his staff, using a "big business" approach,[30] completely turned around the operation, improved morale, and cut the aircraft loss ratio in half while doubling the amount of cargo delivered.

[3][103][ai] A daily direct flight called the "Trojan", flown by select C-54 crews, carried a minimum of five tons of highest priority materiel or passengers between Calcutta and Kunming, then brought back critically wounded patients or aircraft engines needing overhaul.

[101] On 6 January a particularly fierce winter storm blew across the Himalayas from west to east, increasing the time of westbound trips by one hour, and caused 14 CNAC and ATC transports to be lost or written off, with 42 crewmen missing, the highest one-day loss of the operation.

In his memoir Over the Hump, Tunner wrote: If the high accident rate of 1943 and early 1944 had continued, along with the great increase in tonnage delivered and hours flown, America would have lost not 20 planes that month but 292, with a loss of life that would have shocked the world.

[127][aq] These were attached to the EAC Troop Carrier Command[ar] to support the British and were used to fly the personnel and light equipment of the 5th Indian Division to Imphal and Dimapur, where it arrived in time to thwart the Japanese offensive.

[128] The next month, to reinforce Stilwell's planned offensive into Burma, the ICW flew 18,000 Chinese troops west across the Hump to Sookerating, which resulted in a net reduction to the India-China effort of at least 1,500 tons.

[132] ATC's North African Wing had already provided stopgap support by transporting 250 spare B-29 engines to the CBI in April and May 1944, using 25 C-54s over a 6,200 mi (10,000 km) shuttle route from the port of Casablanca to Calcutta that came to be called the "Crescent Blend"[as] until three special mission C-46 squadrons—created in early 1944 under the code name "Moby Dick"—were ready to carry out supply operations for XX Bomber Command.

[134] Designated the 1st, 2nd and 3rd Air Transport Squadrons (Mobile), each was intended to be a self-contained unit of twenty C-46s, flight crews, maintenance and engineering specialists, and a full complement of station operation personnel, although when first committed the service elements had not yet been integrated.

[144] When ATC reorganized on 1 August, the MATS squadrons maintained a separate identity from the newly created USAAF Base Units, but each flew hundreds of Hump missions, delivering aviation fuel and engines.

To alleviate the situation and also provide the additional support needed by the combat forces, 50 C-47s and 20 C46s were permanently based in China after October 1944 for internal movement of cargo and to assist the India-China airlift when gaps in local scheduling permitted.

[154] In April, 50 C-47s and 30 C-46s of the ICD[155][aw] conducted "Operation Rooster", transporting both divisions of the Chinese 6th Army from Kunming, where they had been delivered by "Grubworm", to Chihkiang in the western Hsiang valley to reinforce the defense of the 14th AF base there.

[159] A critical problem proved to be finding a cargo aircraft capable of carrying heavy payloads at the high altitudes required, and three types were tried before the opening of a low Hump route permitted the use of C-54s: C-47 and variants, C-46, and C-87/C-109.

[160] Also, performance specifications of the Douglas transports were not suited to high-altitude operation with heavy payloads, and could not normally reach an altitude sufficient to clear the mountainous terrain, forcing the planes to attempt a highly dangerous route through the maze-like Himalayan passes.

70 were initially planned to fly the Hump with XX Bomber Command, beginning in September 1944, but most of the 218 C-109 conversions eventually served in the CBI under ATC after B-29 operations were shifted from China back to India.

The air route wound its way into the high mountains and deep gorges between north Burma and west China, where violent turbulence, 125 to 200 mph (320 km/h) winds,[26][107] icing, and inclement weather conditions were a regular occurrence.

In the first year of the airlift, inexperienced officers of the Services of Supply[bb] often ordered planes loaded until they were "about full", ignorant of gross weight limitations or center of gravity placement, while most pilots were reserves recently called up from the airlines with little military transport experience and accustomed to civilian safety standards.