Over the Hump

The forgotten – but strategically important contribution Assam airfields had made during the World War II. It had profound significance for the post-war world and, above all, kept China alive during the war, writes JAVED AMIN

The “Hump” – a line drawn across the Himalayas and the forest of Burma by Pilots of extreme courage, valour and blood. It was a high altitude military aerial supply by the Allied pilots in the Second World War, between the Assam Valley, across northern Burma, to Yunnan province in southwestern China, flown during World War II. This operation was the first sustained, long range, 24 hour around the clock, all weather, military aerial supply line in history. It was a start-from-scratch operation. There was no precedent for it. It was a sky road of approx. 900 kilometres long that was flown by the Allied Air Transport Command (ATC) carrying cargo to China from India. Born out of confusion and chaos, it barnstormed its way to maturity and performed its missions with a streamlined efficiency that had profound significance for the postwar world. It had, above all, kept China alive during the war.

Dinjan Air Base – Sometime in 1945


In 1942, China lost the Burma Road, its last remaining supply line to the outside world, due to the invasion of Burma by Japanese troops. American President Roosevelt was persuaded by pressure from China to do something to keep China in the war against Japan. The enemy had literally sealed off China from the rest of the world. Japan occupied all the sea ports and inland river and rail transportation routes by this time. Manchuria, Mongolia, and Burma were all occupied by the enemy. China was isolated and would starved to death. The Chinese military was totally ineffective without supply and was in the verge of collapse.

 On 25 February 1942, President Roosevelt wrote General George C. Marshall that “it is of the utmost urgency that the pathway to China be kept open“. But of course it was far easier said than done. To maintain the uninterrupted supply to China, U.S. and other allied leaders agreed to organize a continual aerial resupply effort directly between Assam and Kunming, China. However, 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.

But the most important factor affecting the operation was the lack of infrastructure in the Assam Valley, which was then, no more than a backwater plantation sector for the British. As a result, a total war effort got undertaken to convert many a tea plantations and other areas into military bases – especially air bases with landing strips. From Chabua in Dibrugarh to Rupsi in Dhubri,including Misamari, Golaghat, Mohanbari etc..– a massive effort in building war infrastructure with hundreds of thousands of local labour were pressed into service.


Plantation Labour laying Airfield
Plantation Labour laying Airfield

The first mission “over the hump” took place on 8 April 1942. Flying from the newly constructed Royal Air Force airfield at Dinjan, Lt. Col. William D. Old used a pair of the borrowed DC-3s to ferry 30,000 liters of aviation fuel intended to resupply the Doolittle Raiders (Remember the 2001 movie Pearl Harbour). Early flights of the strategic operation were basically daylight affairs that were often forced to the northern portion of the Hump. At That time, Dinjanwas within range of Japanese fighters based at Myitkyina, Burma – forcing all-night maintenance operations and pre-dawn takeoffs of the defenseless supply planes. The threat of interception also forced the Transport Command to fly a difficult 800 km route to China over the Eastern Himalayan Uplift, which came to be known as the “high hump”, or more simply, “The Hump”.


From bases in Assam, the planes take off and fly for a few minutes on a course slightly north of east. Rice paddies, tea plantations and jungle thickets slip beneath them, growing denser and denser until they meet with the steep hills at the foothills of what is now known as Arunachal Pradesh. The hills pucker and crumple up from under the jungle, and then are slashed quickly with white rock scars. The scars grow sharper and soon the hills are mountains, the great terrifying spurs of the Himalayas that reach like knuckled fingers to the south. As the official History states :

“The Brahmaputra valley floor lies 90 feet (27 m) above sea level at Chabua. From this level the mountain wall surrounding the valley rises quickly to 10,000 feet (3,000 m) and higher. Flying eastward out of the valley, the pilot first topped the Patkai Range, then passed over the upper Chindwin River valley, bounded on the east by a 14,000-foot (4,300 m) ridge, the Kumon Mountains. He then crossed a series of 14,000–16,000-foot (4,300–4,900m) ridges separated by the valleys of the West Irrawaddy, East Irrawaddy, Salween, and Mekong Rivers. The main “Hump”, which gave its name to the whole awesome mountainous mass and to the air route which crossed it, was the Santsung Range, often 15,000 feet (4,600 m) high, between the Salween and Mekong Rivers. East of the Mekong the terrain became decidedly less rugged, and the elevations more moderate as one approached the Kunming airfield, itself 6,200 feet (1,900 m) above sea level.”

 The Hump contained few enroute navigational aids. Enroute communications were poor, and air traffic control, except for local control towers, did not exist. Aeronautical charts were very unreliable and weather reporting was very poor. Homing beacons existed at each airfield in India and China. These homers were severely affected by weather, night effect, and static electricity that built up on aircraft. Airport instrument approaches were normally conducted to airports on homing beacons and were non-precision approaches.

Added to it were the severe weather which existed on the Hump almost year around. The monsoon season, with heavy cloudiness, fierce rain and embedded severe thunderstorms with turbulence severe enough to damage aircraft. Also, heavy ground fogs, with ground visibilities down to zero/zero, occurred almost nightly and severe thunderstorms occurred over the route on an irregular basis. Winter winds aloft were extreme, often exceeding 150KMPH. Most night flying had to be done by instruments from takeoff due to lack of any ground or horizon references, until well into western China.

As a result, the losses were staggering. The hump became a death route for aircrafts and air crews, which many labelled as “Aluminium Alley”. As one pilot recollected “On a clear day, you could see the sun reflecting off the wreckage of crashed planes lying there.”


Flying the HUMP
Flying the HUMP

Assam bases attacked by Japanese Air Strikes

By late 1942, it was clear that Burma was going to stay closed for a long time, that China was thoroughly blockaded, and that if she were to be supplied at all it would have to be by air from the Assam bases. The Japanese had already begun to realize the importance of the Assam route and in October, the air raids started. On 25th October, 100 bombers and fighters, bombing from 10,000 feet (3,000 m) and strafing from 100 feet (30 m), achieved complete surprise. Dinjanand Chabua were heavily bombed, and nine transports and twenty fighters were destroyed or badly damaged by low-level strafing. The next day Sookerating was strafed by 30 fighters, again without warning. A third raid struck Chabua on 28 October.


But despite the enormous difficulties, the pace of the, then unheard of aerial bridge gathered pace. Day in and out, night after night, amidst heavy showers and malarial mosquitoes, The Assam Backwaters became the hub of Logistics and the life line of the Chinese rear-guard. “We carried everything from millions of gallons of gasoline in 55-gallon drums to fuel air operations, to a full load of Kotex for the women!!   Three mules to a load in a C-47 for pack animals for Merrill’s Marauders in Burma and, just about anything else you can imagine.”  

Overlay of all of the main routes
Overlay of all of the main routes

General William H Tunner’sfinal report stated that the airlift “expended” 594 aircraft. At least 468 American and 41 CNAC aircraft were known lost from all causes, with 1,314 air crewmen and passengers killed. In addition, 81 more aircraft were never accounted for, with their 345 personnel listed as missing. Another 1,200 personnel had been rescued or walked back to base on their own.

 The final summary of logged flight time in the airlift totalled 1.5 million hours and accounted for 685,304 gross tons of cargo carried eastbound during hostilities, dwarfing that of the Stilwell Road (147,000 tons). In addition to cargo, 33,400 persons were transported, in one or both directions. The India-China ferrying operation was the largest and most extended strategic air bridge (in volume of cargo airlifted) in aviation history until exceeded in 1949 by the Berlin airlift, an operation also commanded by Gen. Tunner. Tunner, writing in Over the Hump, described the significance of the India-China Airlift:

 “Once the airlift got underway, every drop of fuel, every weapon, and every round of ammunition, and 100 percent of such diverse supplies as carbon paper and C-rations, every such item used by American forces in China was flown in by airlift. Never in the history of transportation had any community been supplied such a large proportion of its needs by air, even in the heart of civilization over friendly terrain…After the Hump, those of us who had developed an expertise in air transportation knew that we could fly anything anywhere anytime.”

 For its efforts and sacrifices, the India-China Wing of the ATC was awarded the American Presidential Unit Citation on 29 January 1944 at the personal direction of President Franklin D. Roosevelt, the first such award made to a non-combat organization.

 (Javed Amin is a professional engineer and a Supply Chain expert, having worked with reputed companies like Airtel, TVS and TATA. He is currently engaged as a consultant with various organisations including the Asian Development Bank (ADB).)