Great Aviators: Flying the Hump

By Andrew Herd (27 November 2005)

China's role in the Second World War has been vastly underplayed, but the country played an important part in the defeat of Japan, although it made a strange bedfellow as far as the Western Allies were concerned. The origin of what is sometimes known as the Second Sino-Japanese War is usually dated to July 7th 1937, although most Chinese historians disagree, placing the origins in late 1931, at the moment the Japanese occupied Manchuria. From that moment, the conflict smouldered on until 1937, when a concerted push by the Japanese occupied Shanghai, Najing and Shanxi and triggered internal conflict between the Chinese Communists and Nationalists. The country was thrown into confusion, of which the Japanese took advantage and steadily advanced into Northern China. This campaign eventually stalled and so in 1939, the Japanese began a serious bomber offensive against Chinese cities, aimed at breaking civilian morale and destroying Chinese industry - this alarmed Western diplomats and directly led to the formation of the American Volunteer Group, better known as the Flying Tigers, who, somewhat against the odds, formed up in early '41.

If we step backward slightly to 1940, the Chinese factions were devoting almost as much time to fighting each other as the enemy, but Chiang Kai-shek, the Nationalist leader, had realised that his country's only hope of defeating the Japanese was to attract foreign aid. Negotiations were extremely drawn-out, so he bought time by directing his armies to follow a merciless scorched earth policy, the execution of which was so efficient that it is doubtful if history has ever seen its like, with vast areas of productive land fired, water supplies polluted and entire cities destroyed by the retreating Chinese armies in order to deny the enemy access to supplies. The Japanese eventually occupied most of eastern China, but their advance ground to a halt once more in an orgy of atrocities and there things lay until the attack on Pearl Harbor. An idea of the epic scale of this war can be gained from the fact that in addition to over a million Japanese military casualties, 3.25 million Chinese soldiers were killed along with an estimated 16 million civilians. A further 95 million people were turned into refugees, many of them by the scorched earth policy.

Part of the reason for the disagreements about when the conflict started is that until 7th December 1941, China was not officially at war with Japan, which sounds extraordinary until you appreciate that it allowed aid to be sent to it by other, officially neutral, countries: namely Germany, Britain, France, the US and the Soviet Union. On 8th December, China suddenly found that it was at war with Japan, but with America involved, Chiang's priority switched to defeating the Communists, so he divided his efforts between preventing any further Japanese advances and attacking the CCP. Thanks to propaganda from all sides of this tripartite conflict, the situation became more than a little confusing and opinion varies about how much time the Communists actually devoted to attacking the Japanese, though for what it is worth, the Japanese certainly viewed the Nationalists as their major enemy. In the face of this unusual situation, there was an overwhelming need to keep Chiang and the US forces supporting him supplied, because together they were tying up nearly two million Japanese troops that might otherwise have been unleashed in the Pacific.

10,000 tons of supplies were needed per month, which perforce travelled along the Burma road because it was the only adequate overland route into China from India, but in March 1942, an unstoppable push by the Japanese cut it. Disaster loomed. If the Chinese ran out of supplies and were defeated by the Japanese, India and Australia would be at serious risk and with them the whole Pacific theater. With the road gone, it didn't take long to figure that the only way to get supplies into China would be to fly them in; but that meant going over some of the highest mountains in the world. The best route, from Dinjan to Kunming, might have been only 500 miles long, but it crossed a nightmare series of ranges up to 16,000 feet high which harbored some of the worst weather in creation and were within easy range of marauding Japanese fighters, a consideration which led to the opening of two routes to the north, albeit at the expense of flying over even higher ground and pushing aircraft to the extremes of their range. The mountains that separated Dinjan from the destination airfields in China were dubbed 'the Hump', or the 'Rockpile' by the pilots who flew over them, a wry diminutive that discouraged too much reflection about the chilling fact that it was far more dangerous crossing them in summer than it was flying daylight raids over Germany.

Eastbound, the departure airport lay at Chabua, near Dinjan in upper Assam, India. The field elevation in the flood plain of the Brahmaputra is 90 feet above sea level, granting a pilot gunning his engines an awesome view of a wall of mountains surrounding the valley and rising to 10,000 feet or more. The 'southern' route went out of the valley on a course of around 110 degrees magnetic, topped the Patkai Range, and passed over the upper Chindwin River valley, which was bordered on the east by the 14,000 foot Kumon Mountains. From there the plane had to cross a series of 14,000 to 16,000 foot ridges forming the watersheds of the East and West Irrawaddy, the Salween, and the mighty Mekong. One major obstacle, which inspired pilots to name this whole area and the route which crossed it, 'the Hump', was the 15,000 foot Santsung Range, towering between the Salween and the Mekong. Individual peaks along the northern route topped twenty thousand feet.

The other, perhaps bigger, obstacle was that, incredible though it might seem, until May 29th 1941, the US lacked any kind of organisation devoted either to ferrying aircraft or materiel, which had been done on an ad hoc basis until then. On that date, the US Army Air Corps Ferrying Command was created, out of which US Air Transport Command (ATC) subsequently evolved and flying supplies over the Hump was to be one of the new organisation's first tests. Operations began in tandem with the China National Aviation Corporation (CNAC) on December 1st 1942, using C-47s and C-53s to begin with, although these were gradually replaced with C-46s, C-54s and some C-87s (the cargo version of the B-24). In addition some 'war weary' standard B-24s were flown, which gives some indication of how desperate the situation was at times, because this was not a route that anyone would have voluntarily flown in a tired airplane - the CNAC suffered so many losses that it ended up replacing its planes three times over.

Conditions were extreme. Pilots had to coax their heavily laden charges up to altitude, where they faced severe turbulence, icing and thunderstorms. Planes baked on the ground in punishing humidity and temperatures that soared to 130 degrees Fahrenheit, while the monsoon months saw torrential rain fall. Landing strips turned into quagmires, huts leaked like sieves and everything was shrouded in mist, yet takeoffs were expected to be attempted as long as the far end of the runway was visible - at night, a jeep was driven down the runway to clear any animals and pilots took off into total darkness. To make matters worse, cockpits weren't always waterproofed to tropical standards and pilots could find themselves drenched at 5000 feet, yet facing a climb into the icy air above. The demand for aircrew meant that many pilots had vanishing small amounts of twin time when they first arrived and it wasn't unusual for their first flight over the mountains to be their introduction to the C-46 or C-47. In view of this, it isn't surprising that one six month period in 1943 saw over 150 accidents and 168 fatalities among aircrew many of whom were flying over a hundred hours a month, given that the pilots frequently had to combine highly demanding trips with operational training of the guy in the right hand seat. Despite this enormous effort, only a trickle of supplies was delivered to begin with, but by early 1944 the magic figure of 10,000 tons a month was achieved and improvements in organisation and the supply of planes and aircrews meant that this tonnage was soon exceeded. By then, the airlift had become of such strategic importance that the Japanese launched a major offensive with the aim of occupying Imphal and cutting off Assam - had it succeeded, this would have shut down the operation completely, but fortunately the attack was stopped short of its objective.

It is difficult to convey how desperate the situation was in the early days when C-47s formed the backbone of the airlift. Living conditions were appalling, in huts which remained damp from the beginning of the monsoon to the end and were situated in a sea of mud, close to a runway which operated twenty four hours a day. Once you were posted there, you usually stayed until you were shot down, crashed, went crazy or were invalided home. To make matters worse, in the rush to set the operation up, no-one had given any thought to the possibility that crews might need to be rescued from terrain where a fit man might only cover a mile or two a day on foot - and numerous crews were forced to bail out or endure forced landings due to icing, extreme weather, enemy action or engine failures with no hope of being rescued. In 1943, Captain John 'Blackie' Porter started up a rescue team called 'Blackie's Gang' using a couple of C-47s in order to limit the needless waste of life that was occurring - only to discover that finding downed aircrew might be tough, but getting them out was far tougher, thanks to parts of the area having been infiltrated by the Japanese, so his rescue crews had to travel well armed. The heroic and largely unsung Blackie was lost on a search and rescue mission in December '43.

There are a few challenges involved in recreating a Hump flight, beginning with the unfortunate fact that Microsoft's Himalayas are considerably tamer than the real thing, thanks to the mesh elevation model in FS2004 in this area being based on a model which uses 1223 metres between data points - by contrast, the resolution of most of the US terrain sports double the resolution, with some areas being four times as good. Since mesh doesn't have too great an impact on frame rates, I rectified the situation by downloading and installing some of FSGenesis' excellent mesh scenery. Very conveniently for the purposes of this review, FSGenesis offer a 76.4 metre resolution Himalayas mesh upgrade for $9.95, which represents outstanding value for money, although the downloadable package is definitely only for broadband users, given that it is within a whisker of 600 Megs - the good news being that having the CD version delivered to your door only costs another five bucks. Do bear in mind, by the way, that installing non-standard mesh brings the risk that some airfields will end up on small mesas or in canyons, partly because FS2004 assumes that all runways are perfectly flat (which they are not) and partly because Microsoft appear to have gotten some of the field elevations wrong, or at least picked some imaginative values for them.

As luck would have it, the Hump lies on the very southern edge of the Himalayas, so I downloaded the SE-Asia and Indonesia pack for safety's sake, which was another 677 Mb. All this sounds like a lot of hard work for no purpose, but it is hard to emphasize how much difference installing a really good mesh makes and if you have never tried any of the FSGenesis packages, now is the time, because having the FS2004 mesh vertices plotted over a kilometre apart produces a tamer landscape than the craggy wilderness the ATC and CNAC crews knew and rightly feared. You only have to look at the mesh from the air to realise what a nightmare a forced landing would have been, because there is absolutely nowhere that would be safe to put a plane down over most of the route, beyond maybe some of the river banks. And once you were down, you were lost, with virtually no hope of anyone ever finding you again. FSGenesis have long gone unthanked by me for providing some great mesh and even better service, so an Armchair Aviator is well overdue.

In addition to some new mesh, I decided to spiff up Microsoft's dull Himalayan landscape with some of Ruud Faber's FScene ground textures because the major risk flight simmers face from the default landscape is being bored to death by it, Microsoft's Asian textures lacking a certain je ne sais quoi. We have reviewed the FScene textures many times in the past, so they need no introduction, but if by any chance you haven't heard of them, check 'em out. Ruud Faber, the talented artist behind FScene, has provided replacements for every single one of Flight Simulator's default ground textures, for every part of the world, in every season. Quite apart from the fact that this must have been a mammoth undertaking, the results are nothing short of spectacular and a complete antidote to the boredom that tends to set in when you load another flight only to discover that you are flying across the same old landscape. The FScene textures are justifiably popular and the only problem I have come across with them is that addon sceneries that incorporate ground textures are normally color coordinated with the default Microsoft textures, which means that third party airfields can end up standing out like due to the mismatch.

I haven't had an opportunity to see the Asian textures before, but they are as good as anything Ruud has ever done - better, because he has taken the opportunity to enhance the landscape with little groups of paddy fields that look almost magically real from the air - you can see them upper left in the first large format screenshot below. The textures are sold either as a single season for a single continent, which is relatively expensive at €15; or you can buy all four seasons for a single continent, which makes good sense at €36; or you can buy four seasons for any two continents for €44, which is a bargain. Ruud already has an Armchair Aviator for his efforts, so here is confirmation that I still think his work is among the best out there.

The obvious choice for the plane was Microsoft's default DC-3, but the flight model isn't that good and the fuel management has been drastically simplified, removing half the challenge of flying the plane in the conditions I planned to encounter (-: So an alternative was needed and I guess it won't surprise anyone that I chose the MAAM-Sim C-47, because it has a far better air file, a much more realistic panel and an extremely good visual model, not to mention the fact that it has been the product of a campaign of continuous improvement going back many years. I used the 7th edition package, which is available on CD from the Mid Atlantic Air Museum store for $30.00.

If, after all you are going to see and read in this article, you still need a reason to pay for this classic package, it might help to know that it is compatible with FS2004 and FS2002, installs a USN R4D-6, UAL and BEA DC-3s, two different XC-47C amphibians, two C-47s in D-Day livery and two RAF Dakotas - and that the rest of the disk is packed with manuals and videos. Every copy helps keep the Mid Atlantic Air Museum's R4D in the air and it is one of the best simulations around of any airplane, period - so the MAAM-sim disk gets a long overdue Armchair Aviator Gold award.

Finding a livery for the C-47 was more difficult. The only CNAC scheme I could find was for an FS98 plane and wartime ATC C-47s seem to have been almost completely forgotten, let alone any planes which might have flown the Hump. Having sorted through reams of classic airline repaints, I compromised in the end and used Stephan Demmelmeier's 'Berlin Train' (BERL_TRN.ZIP), because it was one of the few military liveries that didn't sport invasion stripes and shows an appropriate amount of wear and tear.

One other piece of kit turned out to be indispensible for recreating the flight was CH Products' new throttle quadrant, which, if it is anything like my CH yoke, will prove to be a faithful companion in the virtual skies. I was sent one for review a few weeks back and have been seriously impressed with it - the unit has six levers with interchangeable colored tops, so you can set it up to simulate anything from a four engined jet console to a GA twin quadrant simply by swapping the tops around. In addition, the CH quadrant has six flipper controls ranged along the front of the unit, so that at long last I have been able to find a spare hardware control to which I can assign the C-47's cowl flaps, correct operation of which is vital if you want to get where you are going in a timescale you can get your head around. The levers all have a detent, which lets you set up a flight idle position, which is very handy for jets and turboprops, if not for the C-47 and the only configuring you have to do is to plug it in to a spare USB port and set it up via the Windows control panel. I will give the unit a full review shortly, but believe me when I say that it revolutionises handling twins and the heavies.

The first problem I faced was finding out if the airfields used in the flights over the Hump still exist and if so, whether they could be found in FS2004 and to my slight amazement, they all are. I guess that on reflection, it isn't so surprising that the fields are still around, because for all that they started from small beginnings, the strips ended up being built to high standards and when Air Transport Command left, the host countries very sensibly kept the infrastructure going. Chabua (VECA) reverted to the Indian Air Force, who substantially upgraded the facilities after the Chinese invasion of Tibet and - as far as I know - hosts Mig-21s squadrons today. All three of the Chinese fields still exist, although inevitably, they have changed greatly over the intervening sixty years. The youngest of the pilots who flew the route will be in their eighties now and this piece is a tribute to them and to the ground crews who supported them. Had they not 'lived like dogs and flown like gods' as the saying went, the outcome of the war in the Pacific might well have been very different.

What we are going to do is to fly a mission over the Hump - a routine, easy one, because Flight Simulator doesn't do a great job of simulating the weather in this region, partly because it is so far away from any reporting stations and partly because conditions in the Himalayas and other high mountainous regions are so specialised that the FS weather engine can't produce them to order. The major problems in this area tend to occur in summer, rather than winter, when the weather is generally good, thanks to the dry prevailing easterly winds that sweep down from Siberia. In summer, the south-west monsoon brings warm wet air from the ocean across the Indian land mass to fill the area of intense low pressure that develops over the Himalayas - which translates into phenomenal amounts of rain (some places get up to 10,000 mm), enormous cu-nims, icing, violent clear air turbulence, mountain wave, and extreme upper winds. In practice, you can simulate monsoon conditions by loading the thunderstorm theme, but as an alternative, try setting the season to summer, the dewpoint within 3 degrees of the air temperature and a low barometric pressure, then wait to see what happens. I did my simulated flight of the route in September, when the Calcutta TAF was this:

CALCUTTA/DUM DUM VECC 120300Z 120606 07008G18KT 5000 HZ SCT015 BKN090 BECMG 1012 4000 HZ BECMG 1618 07008KT 3000 HZ BECMG 2123 07005KT 2000 HZ BECMG 0103 07008KT 3000 HZ BECMG 0406 07008G12KT 5000 HZ TEMPO 0606 1500 TSRA/SHRA SCT010 FEW025CB OVC080

From past experience, that doesn't represent unusual late season wether, with bad haze (the distances are in metres, so 5000 means just over a couple of nautical miles), gusty easterly winds at times and the threat of thunderstorms ever present. A modern GA pilot would stay home in the face of a forecast like that, unless he had an instrument rating and an FAA certified lucky rabbit's foot, but this is wartime...

Okay, so today we have a thunderstorm, but unfortunately you can see the end of the runway, so you are going to have to takeoff. As you advance the throttles, you tell your worried-looking co-pilot to look on the bright side, because maybe the bad weather will keep the fighters down. You lift the gear, then the flaps and turn onto 110 degrees before reducting the rpm to 2300 and raising the nose until the airspeed indicator shows 105 knots, the recommended rate of climb for the C-47. The mist clears for a second, just long enough for you to see the paddy fields below and then you are into the cloud and on instruments.

The plane runs into a patch of turbulence and your co-pilot goes green. This is his first mission over the Hump and you can already see the fear in his eyes. He isn't familiar with the C-47, so you have told him to keep a lookout and watch everything you do - when you have time, you will do some training. You know he needs encouragement, but you don't say anything, because you are concentrating on the climb, watching the instruments, nursing the engines that you may have to rely on to give maximum continuous power for long periods should you hit the big downdrafts that you know lie out there. Some pilots have reported five or six thousand feet per minute vertical wind speeds. Some pilots never got to report anything at all. You have ridden updrafts inside thunderheads that took you to thirty five thousand on westbound headings, before trading height for speed in a wild ride across the roof of the world. You have circled above the field, gaining height in absolute darkness, before setting out to the east and you have seen sights that other men will never see, a veteran of the Hump at only twenty years old.

The cloud clears a little and the guy in the right hand seat cheers up a little. Hey, it's not so bad, is it, huh? he manages a weak grin. Yeah, you reply, it is not so bad. You think of the mountains ahead. You need maybe fourteen thousand to clear the first range safely and even with the plane complaining as it claws its way up through the hot air, you know you are going to make it. The C-47 feels overloaded, probably is - no-one checks them that seriously. Stuff gets put in until no more will fit and then you fly. Or not. At either end of the runway there is a sad pile of bulldozed hulls that never made it off the ground because the CofG was so far out.

You pass ten thousand, concentrating on keeping the 110 degree mark a shade to the left of the line so you can steer as near to 108 as you can judge. More turbulence, but the thunderhead is behind you now and while visibility isn't great, it isn't so bad, either and it is getting better the higher you go. With winter on its way, flying conditions can only improve, but it will get cold, so very cold.

At 12,000, you hit the wall on manifold pressure and it begins to drop below 38 inches, so you briefly level the aircraft, reduce the revs to 1700, change the blowers into high gear and then advance the throttles before commencing the climb again. You show your co-pilot how to do this and remind him that whatever gear the blowers are in, it pays to switch them into the other one for ten minutes every couple of hours to stop the oil sludging. He raises his eyebrows, but you tell him to be glad you aren't flying in one of the C-46s the unit has been sent, because the Curtiss electric props on them have a habit of going into fine pitch for no reason whatsoever and occasionally come off, with disastrous consequences.

At 14,000, the manifold pressure falls below 38 despite being in high gear. You still need another 3000 feet, minimum, but you know the plane will begin to struggle. As it does. The engine note slowly changes as the old plane heaves itself slowly higher, the rate of climb down to a few hundred feet a minute now - but at least it is clear. Pffffffffffff - a big downdraft drops you a thousand feet in what feels like a couple of seconds. Your co-pilot, who has been day-dreaming, wakes up - what the f*** was that? he asks, wide-eyed. You look at him, then out the window. It sure looks peaceful down there... but even now, if you came down, less than an hour from Chabua, you would probably die in the jungle if you didn't die in the crash. You look back at the guy in the right hand seat, two years younger than you, and you wonder if he knows anything about that. Don't worry, that was just a small air pocket - just wait until we find a grown up one! You grin and he grins back.

At 16,000, the OAT is minus 10, warm for this time of year and so the plane is inching its way up. The view is absolutely awesome. You ease the nose down, throttle back to 30 inches, reduce the pitch to 2000 rpm and put the blowers back into low gear. The C-47 feels more than a little ponderous at this height, but she speeds up and you catch sight of the upper Chindwin river glittering far below.

There people down there? asks your buddy. Yeah, you reply. There are Japs and some weird British general called Wingate and a bunch of guys with him who live like animals... and there are headhunters.

No kidding? Headhunters? Behind the mask, his face is a picture. Yep, headhunters. They say they are our headhunters, but I guess maybe a few of them might not know that.

So how come guys like that like us so much? he asks. You grin. Because we give 'em a bag of salt for everyone they return alive. They sure seem to like salt - only problem I got with it is how we know when they have got enough salt.

He points out a line of cloud in the distance - bad weather ahead? You shake your head, because it isn't cloud. It is a sight you have seen more often than you wish to count; the beginning of the Hump. You have flown over it, and back, no less than 84 times and each time something has happened to make your mouth go dry and the sweat start out on your back. Twice you have had to return because of headwinds - one time they were so strong that your position did not change for an entire hour, while you battled to stay in the air before giving up and turning back. You were glad you gave up early that time, because several planes were lost that night, mostly when they encountered severe icing in lower lying cloud that you were lucky to avoid.

But today, the weather is good and you can see forever. The downside is that so can the enemy and if any fighters have ventured out, you are dead men, because there isn't a shred of cloud thick enough to hide the C-47 in. You ask him to keep a good look out, not that it will help much. In this thin air, with the C-47 able to climb at barely 200 feet a minute and the mountains looming close below, the first firing pass would probably take you down. So you fly, hour after hour, living on oxygen and your nerves.

But the fighters don't come. Kunming, today's destination (Wujiaba, ZPPP today), is the easy route as long as the fighters aren't active. The more northerly flights to Chungking (Jiangbei, ZUCK) and Chengtu (Shuangliu ZUUU), pass over the main ridge of the Jade Dragon Mountains, just to the south of the Snow Mountains and perilously close to Gongga Shan's soaring 24,790 foot peak. You have flown both of these, many times, sometimes forced down by the weather so that you have had to duke it out in the passes, other times in cloud almost all the way, never catching sight of the mountain or the high plateaus of the Himalayas until it was time to descend on the other side. Once, you got caught in turbulence so bad it flipped the plane end over end, breaking the ropes that held many of the cases of wolframite so that they crashed around inside the hold and then slid aft, leaving the plane so tail heavy that it took both pilots to hold the nose down while you figured out what the hell you were going to do - a decision you never ended up having to take because another huge bump stood the plane on its nose and cured the problem, although when all the crates slid forward they jammed the cockpit door so you had to wait for the guys to unpack everything before they could lever you out. That C-47 never flew again, because the cabin was wrecked and hundreds of rivets had started in the wings and they just added it to the pile of junk at the end of the runway. It was years later before you realised that you must somehow have flown through a rotor and survived when so many others had not - so many of your flights had encountered weather phenomena that weren't properly understood at the time, like the jet stream. Another time you took off behind a C-46 and flew in heavy cloud all the way, only have sight, a couple of hours out, of its huge empennage sliding across in front of you in paralysingly slow motion, before it vanished again - the funny thing about the encounter being that it was the only time you saw another plane in flight across the Hump.

You will make it through the war. In your old age, you will often think of your co-pilot on that trip, a guy whose name you never had time to ask, because he ended up being posted missing in action the very next time he flew. Sometimes people ask what you did in the Air Force and you will tell them that you flew transports and they will ask if you missed the danger of flying on active service and you will think of the Hump and the impossibility of telling them what it was like and how important it was. And that makes you think of that guy again, killed before he had a chance to grow up because of a war no-one has ever heard of - and you know that John Donne was right when he wrote '...never send to know for whom the bell tolls; it tolls for thee.'

Be glad those men flew like gods.

Andrew Herd