On the edge of Omarama airfield, local pilot Gavin Wills motioned to the sky and asked, “What’s happening up there?”I hoped the question was rhetorical because the mess of clouds aloft meant nothing to me. I realized that after spending every day of my life under its influence, I knew virtually nothing about the single most dominant feature around me—the sky.
Noting my vacuous expression, Wills indicated with his hand: “If you look along that cloud line, a wave is forming.”“A what?” I asked. Thus began my pursuit of the wave.
Invisible waves of air, particularly on the lee side of mountains, are the key to modern long-distance gliding—or soaring, as the preferred term is today. Although this windy swell can’t itself be seen, cognoscenti can read its presence in particular cloud patterns. But such airwaves, so sought after by modern-day soarers, have not always been so favorably regarded. When gliding was in its infancy, pilots believed that wind in the lee of a hill or mountain hugged the ground, producing a downdraft. In 1933 two German pilots, Hans Deutschmann and Wolf Hirth, serendipitously discovered a powerful type of lift when they strayed into what was then considered the “downdraft zone” on the lee side of a small hill in Silesia, at that time part of Germany. In their flimsy wooden-and-canvas glider, Deutschmann and Hirth were unexpectedly thrust skyward.
News of this reached a young scientist and glider pilot called Joachim Kuettner, who became the first to study the phenomenon scientifically. At a gathering of gliding enthusiasts, he convinced pilots to carry recording instruments and to fly to the lee side of the hill. Analysis of the data they collected confirmed his suspicion that wind flowing over mountains generated downwind waves very similar to standing waves in river rapids. On the front edge of each wave was a very smooth and powerful zone of lift. Kuettner coined the phrase “mountain wave”.
Discovery and exploration of the New Zealand mountain-wave system had to await the exploits of Dick George son in the 1950s. George son and a friend, Jon Hamilton, scratched up enough money to buy a Slings by Prefect glider. They used a Bentley to tow it fast enough to lift off, which it did at 55 kph. After four successful launches they had met the airworthiness criteria for graduation to aero-towing and were soon hitchhiking into the sky behind Tiger Moths. So began the exploration of South Island skies by sailplane.
By this time Kuettner was working for the US Air Force, exploring the Sierra Wave in California (along the Sierra Nevada). George son began to wonder if the nor’west arch, the distinctive cloud formation that heralds Canterbury’s notorious föhn, indicated a local equivalent of the Sierra Wave. With a northwester blowing on January 2, 1952, George son took his little Prefect to the Two Thumbs Range near Lake Tekapo in an attempt to break the national altitude record.
It was a brilliant morning and the whole expanse of the Mackenzie Basin was unfolding before my eyes. Mount Cook stood out in splendor above the cloud that was pouring over the Copeland Saddle and around Mt Sefton. There were the lakes beneath me and further south Lake Ohau sparkled in the distance. This was incredible—a far cry from the little ridge at Dunstable.
Georgeson kept climbing until he reached an altitude of 10,600 ft* (3233 m), enough to give him the national Absolute Altitude and Gain in Height records. The daring pursuit of cross-country flying was the next challenge.
During World War II, bomber pilots flying long missions were the first to encounter extremely strong easterly winds at high altitude (about 12,000 m). These winds became known as the jet stream. Having described mountain waves, Kuettner believed it would be possible to fly long distances in them using the jet stream. This was a novel concept at a time when almost all longer-distance soaring flights were made using thermals. Kuettner’s concept was to fly to the crest of a wave, surf downwind in the core of the jet stream, join another wave, climb to its crest above the next mountain range, and again surf down in the jet stream.
In March 1952, Kuettner used this technique to make the first significant downwind flight. In a low-performance glider, he crossed seven mountain ranges and flew 373 straight-line miles at altitudes of between 20,000 and 40,000 ft (6100 and 12,200 m) at an average ground speed of 94 mph (150 kph) and a maximum ground speed in excess of 200 mph (320 kph). It was a remarkable achievement at a time when most aircraft could climb to only 10–12,000 ft (3000–3700 m) and fly at 100 mph (160 kph).
Of course, the South Island runs perpendicular to the prevailing westerly winds and is too narrow for significant downwind flying. However, the nor’west arch, which forms on the lee side of the Southern Alps, can run almost the entire length of the island. Georgeson wondered whether he could use the wave whose existence he had demonstrated to make long-distance crosswind, rather than downwind, flights.
On February 8, 1953, he flew 90 miles (145 km) in the first significant crosswind wave flight. Six weeks later, on March 25, conditions looked ideal for another attempt. Local flying authorities, unaccustomed to dealing with gliders, requested a flight plan with details of engine and fuel type, intended route and estimated time of arrival. Slightly embarrassed, Georgeson conceded he was unable to provide the required information. Instead, he fudged the plan, presenting an ideal scenario, then took off 204 miles (328 km) from his declared destination.
“I was sitting comfortably above the slipstream of the Tiger Moth until we released north of Oxford,” he recorded. “I met some rather violent ups. Marking my position on the ground I held on to the lift and I started to climb well.”
Unlike Kuettner, who had the US air force behind him, Georgeson had the barest of resources, and this was the first occasion on which he used oxygen. At 14,000 ft (4270 m) he pulled his oxygen mask on, but the clip for holding it in place broke. For the rest of the flight he was forced to hold the mask to his face. Unsure whether he was getting enough oxygen to keep hypoxia—a shortage of oxygen in the body tissues—at bay he kept checking the whites of his nails to see if they had turned blue. He climbed well to 22,000 ft (6710 m) and headed south along the leading edge of the wave—rather like a surfer cutting back along the face of a wave and riding it parallel to the beach.
The canopy started to ice up inside and I noticed that I was just slightly behind the leading edge of the nor’west arch so characteristic of Canterbury. It was incredibly exciting to be nearly touching it. At 22,000 ft I could see over the Southern Alps to the West Coast and I realised for the first time what a geographically narrow country we are.
During the flight there were several heart-stopping bangs that made Georgeson wonder if his plane was integrating as a result of the extremes of wave flying.
By the time I got to the Hakataramea Saddle I was at 12,000 ft and then, in the lee of the Grampians, I sailed into a beautiful strong silky wave surging to 22,000 ft. I was getting desperately cold and uncomfortable. Running south I reached 18,000 ft west of Hampden which was enough height to get me to Taieri if I could keep out of the ‘downs’.
Over Palmerston, Georgeson reckoned he would clear Flagstaff by several thousand feet, so he pushed on to the Taieri basin. It wasn’t until he had landed at his destination—to the very minute specified in his flight plan that the unnerving bangs were explained. “As I opened the cockpit the Perspex fell out.” The metal frame and Perspex canopy had very different contraction rates, and in the extremely low temperatures the Perspex had been distorted and cracked.
As for George son’s accomplishment, “Air traffic control was incredulous not only that a glider had arrived in Dunedin all the way from Christchurch, with no power apart from wind, but that it arrived on time. I was pretty surprised myself.”
So far Georgeson had travelled only one way. Was it possible to go in the opposite direction? How high did the wave extend? Was lift always to be found on the lee close to the mountains? Just how far could one go? Clearly, there were mighty possibilities. Right now, though, Georgeson had made the first major crosswind wave flight anywhere in the world, and his feat earned him international recognition.
On December 16, 1960, near Horarata just south of Christchurch, Georgeson appeared dressed more for polar exploration than the scorching temperatures of the northwester. He had already soared higher than Mount Everest, setting a national Gain in Height record, but he wanted more. His oxygen system was now far more sophisticated than in the early days. A pressure demand regulator automatically delivered the appropriate level of oxygen for altitudes of up to 39,000 ft (11,900 m). The gas was pumped into the lungs to get more of it into the blood. A major disadvantage of pressure demand breathing, however, is that you have to forcibly exhale, which Georgeson found uncomfortable.
An initial foray aloft didn’t last long, but by early afternoon conditions looked better and Georgeson was towed to 3200 ft (975 m). After releasing the line, he hit a strong downdraft and it took every trick he knew just to stay airborne. A while later he struck a thermal that was slow to lift him and unpleasantly rough, and he struggled for an hour to reach a mere 5000 ft (1525 m). Then he noticed that the nor’west arch had fully formed and stretched as far north and south as he could see.
“The ranges to the far west were capped in cloud and I was probably some 30 km down wind from the leading edge and going up. It was tremendously exciting.” He continued to climb steadily to above 25,000 ft (7626 m), where the lift finally petered out. “I didn’t know if I’d lost my position (in the wave) or reached the top of the wave. I seemed to have climbed into the back end of a gigantic primary wave cloud and realised I was flying in the nor’west arch itself.”
The only way Georgeson could go higher was to dive through the cloud, jumping from the wave he was on and re positioning himself upwind on the leading edge of a parallel—and hopefully larger—wave. After diving he contacted a fresh wave at 9500 ft (2900 m) and was thrust back up to 17,000 ft (5185 m) in a matter of minutes. At 19,000 ft (5795 m) the lift stopped, and he decided to return to the wave he had just left. Again he climbed steadily to 25,000 ft, where a significant drop in temperature fogged up his canopy with a layer of frost. The cold began shrinking the cables to his ailerons, making control more difficult. However, “If the ailerons froze up completely the air brakes would at least limit the speed so I wasn’t too worried.”
Georgeson soon passed his record of 32,500 ft (9910 m) and worked hard to hold his position in the strong lift. Eventually his altimeter read 36,100 ft(11,010 m). “I was right over the top of the nor’west arch and looking down the dazzling cliff face of cloud stretching 5 km below me.”
By now the –57°C temperature was really starting to bite. Each outward breath instantly froze, creating a puff of ice crystals, Georgeson had long lost all feeling in his feet, blood oozed from the most trivial scratches on the back of his hand and thick ice on the canopy meant he was essentially flying blind. “But, cold be blowed, I had never been so excited in my life.”
He couldn’t see a thing unless he opened the canopy. The instruments were behaving strangely and were probably frozen. “I searched and searched for lift but found nothing.” By this stage the ailerons were totally useless so he hauled on the brakes. Nothing happened. This was unexpected, and Georgeson’s euphoria froze with the onset of rising panic.
Whenever glider pilots venture above 30,000 ft (9000 m), they breathe pure oxygen and the dangers increase dramatically. Pressure breathing is unnatural and, as a result, Georgeson started hyperventilating. A pilot short of oxygen at 33,000 ft (10,000 m) has 30–45 seconds of useful consciousness in which to react. The combination of shallow breathing and rising panic meant Georgeson wasn’t getting sufficient oxygen. “I felt I was losing control of the aircraft. I had to descend.”
By dint of sheer willpower he suppressed his emotions and took control of his breathing. “I had enough sense to turn the oxygen pressure-demand to neutral to give balanced breathing. Then I pulled again and again on the brakes.” Still no response. With every second the danger mounted. “I maintained steady pressure and the brakes flew open with a bang. They were now frozen open, but that didn’t matter, because as I came down the temperature would go up and they would thaw for the approach and landing.”
Panic gave way to relief and then to excitement once more when he contacted air-traffic control.“I remember saying, ‘Christchurch this is Golf Charlie Foxtrot. I am at 35,000 ft descending over Porters Pass. I think I have a world record.’ The exuberant response gave me a thrill. ‘Congratulations. If you look down you will probably see the DC 6 coming in from Australia.’ I looked down, and there, 20,000 ft below I could see a tiny little aeroplane. It was a nice moment.”
Georgeson was left with more than memories. He had set a world record for Gain in Height, and the subzero temperatures had given him frostbite in his feet and the backs of his hands. Eventually the soles of his feet and the back of one hand peeled away and the resultant sores persisted for many months.
At present the world record for high-altitude gliding is 49,009 ft (14,948 m), set by American Bob Harris in the Sierra Nevada. Former NASA test pilot Einar Enevoldson and wealthy American adventurer Steve Fossett have taken up the challenge of breaking this record, basing themselves at Omarama, in North Otago. They have spent the last three winters (2002, 2003 and 2004) learning the idiosyncrasies of the local mountain-wave system. Their operation is named the Perlan Project after the mother-of-pearl-coloured clouds found at high altitude, and aims to double the altitude record.
For Enevoldson, the Perlan Project is about discovery and crossing into the unexplored. He was once an apprentice mechanic on Kuettner’s Sierra Wave project. Forty years later he emerged as one of the world’s best high-altitude test pilots after putting five planes through their paces above 70,000 ft and solving the problem of flat-spin recovery in F-14s, made famous in the movie Top Gun. While working in Germany in 1991, he noticed an image taken using a Lidar—a laser–radar hybrid that showed a beautiful sinusoidal pattern in the atmosphere between 65,000 and 100,000 ft (19,800 and 30,300 m). “As a gliding pilot I looked at the image and knew it was a mountain wave.”
The science behind the Perlan Project is very sophisticated and requires expertise to match.“I know enough about meteorology, physiology, aeroplanes and aerodynamics that I can make a pretty good go of it,” explains Enevoldson. “Originally I thought 80,000 ft would be a nice goal but then, with some very careful analysis, it looked as if 100,000 was actually achievable.”
Soaring this high would mean flying out of the troposphere (the innermost of the four layers into which science divides the atmosphere), into the middle stratosphere (the next layer), which is about a third of the way to space.
Why mount the attempt at Omarama using the South Island wave system? The most important reason is the so-called polar vortex. Earth orbits the sun on a tilt, which accounts for the seasonal variations of light and temperature, most pronounced in the polar regions. As one pole basks in summer light and warmth, the other shivers in winter dark and cold. The air in the winter latitudes cools, increasing in density as it does so and sinking towards the pole. At the same time, Earth’s spin makes the frigid air circulate, so the overall effect is like water spiraling down a plughole. This huge mass of rotating, sinking air is the polar vortex. At the outer boundary of the vortex the stratospheric winds speed up. Although the vortex is well south of New Zealand, in some years the effect on the stratosphere extends as far north as the South Island.
Without the polar vortex, winds seldom extend above the tropopause—the interface between the troposphere and the stratosphere—which usually lies between 30,000 and 40,000 ft (9150 and 12,200 m). Surface-generated winds are effectively extinguished at the tropopause. The polar vortex, on the other hand, stimulates a wind field from 100,000 ft (30,500 m) down to the tropopause. For a glider to soar much above the tropopause, the polar-vortex wind field must be aligned with a favourable tropospheric wind field. There doesn’t appear to be much, if any, correlation between the two wind systems, but occasionally, apparently by chance, they arrive over the Southern Alps together, and the mountain wave can then rise to extraordinary heights. More of these stratospheric mountain waves have been recorded by the National Institute of Water and Atmospheric Research (KIWANIS) at its Lauder weather station in North Otago than anywhere else in the world, some of them reaching above NIWA’s highest balloons, at 120,000 ft (36,600 m). These are the winds that Enevoldson and Fossett believe will take them to their world record.
Another advantage of Omarama is the help available from local pilots. The wave systems in the area are complex, but aviators familiar with their intricacies are generous with advice and keen to act as scouts for Enevoldson and Fossett. All the same, says Enevoldson, “Our main problem is being ready at the right time. We could miss out because we don’t find out that the wind is optimal.”
When a wave is really pumping, its power is palpable. The frequency of mountain waves is too low to register on the ear, but the pressure fluctuations generated by the waves can be felt through the body like a deep resonating hum—a subaudible vibration as if a bow is being drawn across the bottom string of a monstrous double bass.
I stood beneath such a wave on the Omarama airfield with Gavin Wills watching Fossett and Enevoldson, decked out in pressure suits, getting into their customised DG 505 sailplane. Looking more like astronauts than glider pilots, they finalised their ground checks and prepared to launch. The wind was extreme, the leafless poplars on the edge of the airfield bent almost double. Directly above the field floated a massive lenticular, or lens-shaped, cloud—a classic indicator of a wave system—but the prospect of flying through the lower-atmosphere turbulence to get to it was daunting. The general consensus among the local pilots was that the turbulence would make it very difficult to gain much height. Sure enough, the Perlan glider was back on the ground within an hour.
Later in the afternoon I met up with Enevoldson to discuss some of the risks of their project.“It is possible but extremely unlikely that a very large gust could simply break the glider,” he explained. “Gliders are built very strongly—much stronger than powered airplanes. Second, one could encounter a sequence of gusts or turbulence that would result in the sailplane going ‘overspend’. Gliders are only built to withstand certain forces, and going at excessive speed may place too much stress on the airframe or it may cause buffering, loss of control or flutter. Hence for each glider there is a VNE—velocity never to be exceeded. For the extremely high-altitude flying, we have to fly pretty close to that limit and it would be fairly easy to go beyond it. The problem is that the density of air decreases as you go higher. At 100,000 ft (30,500 m), because of the low air density, the glider cannot be flown below a speed of about 0.6 Mach (or it will stall), and the VNE is about 0.7 Mach. This knife edge gets sharper as the altitude increases, until you reach the altitude referred to as coffin corner, where stall speed and VNE meet.”
Stowed in the Perlan glider’s tail is a large drogue—a funnel-shaped parachute for deployment in an emergency to reduce the aircraft’s speed. With the drogue deployed the pilot can go into a steep dive, so if, for instance, one of the pressure suits fails, the plane can be rapidly brought down to a safe altitude.
Above 39,000 ft (11,900 m) even pure oxygen is insufficient to maintain useful consciousness. This is because the atmospheric pressure is too low to drive oxygen across the alveoli, or air sacs, in the lungs into the blood, resulting in hypoxia. There is worse. The boiling temperature of water falls with increasing altitude, and above 62,000 ft (18,910 m)—known as Armstrong’s Line—water will boil at human body temperature. Only brief unprotected exposure to altitudes above Armstrong’s Line is survivable.
A pressure suit—that is, a space suit—keeps the body at a pressure equivalent to that below 35,000 ft (10,675 m). The person inside breathes pure oxygen, exhaling into the suit. The exhaled air inflates and pressurises the suit, while a relief valve prevents over inflation. Flying at 35,000 ft for an extended time poses another risk—the bends. At low pressure, nitrogen in the blood comes out of solution and forms bubbles. Lodged in the brain or lungs, these can prove fatal. Treatment involves an immediate descent and repressurisation.
“By the time we get to 35,000 ft,” Enevoldson told me, “we will have been breathing pure oxygen for a couple of hours and that should have got rid of most of the nitrogen in the blood. As air force pilots in the early jet days, we used to get the bends routinely but thought little of it. Then, as one of the guys was landing, his vision went totally red. From that day on, we all got a lot more serious about the bends.”
Enevoldson’s hero is Amundsen, who “did everything so well, planned it so thoroughly, that he handsomely succeeded in reaching the South Pole first. It was a difficult job but he went about it the right way and he didn’t hurt anybody.”
Returning to the Perlan Project: “The problems being encountered are exactly what were predicted. People have tried to get to 50,000 ft but haven’t made it because after five years they run out of time, enthusiasm or money. We are trying to fly twice as high as anyone has flown in a glider before, higher than an SR71, a U2 or any aeroplane can fly. It can be done, but like all high-altitude flying, it takes money, determination and a huge technical and logistic programme.
“In another five years I am going to be really old. I am already really old. I am 72 now and Steve [Fossett] talks about the year after and the year after. Even if nothing serious happens, you do start to lose your energy, but there is also the possibility that something will disable you. Ideally, I would like to be the one to do it but, more than that, I want to see it get done. I would like to figure out a way to make this a Kiwi project. I’d like to find the right people and point them in the right direction. They live here so they know the skies down low, have a better chance of being here at the right time, and they are some of the best pilots in the world.”
We broke a world record yesterday,” Steve Fossett told me. “Go say hello to Terry.” He was referring to Terry Delore, New Zealand’s leading exponent of wave soaring. Moments later a dishevelled looking man on a mountain bike wheeled past clasping a cup of coffee. I asked if he knew Terry Delore. He looked up at me with squinting eyes that betrayed late-night excess.“Yeah, I know him.”
I explained I wanted to find out more about waves.“Actually, I am Terry,” he replied. “And I’m late for a meeting I didn’t know I had.” He wobbled off. Delore and Fossett have made four attempts together at the 1000 km out-and-return record. On the fourth, Delore focused on flying and Fossett on navigation. With calculator, stopwatch, GPS and maps in hand, Fossett calculated the exact altitude, time, longitude and latitude of the start point. “We weren’t to know how important all that information was going to be until the last 100 km,” recalled Delore. Navigation must be perfect during record attempts, for there are no signposts, no officials and no tape at the finishing line in the sky.
The first 900 km of the flight went exactly according to plan. But excitement at the prospect of a world record dissolved when the two men saw the only thing likely to stop them—dark storm clouds. Tails of rain and hail stretched from the cloud base to the ground, obscuring their finish point over Clyde. Thirty-five kilometres out they crashed into these. Emerging from the other side, they saw more cloud engulfing the finish point.
“These planes do not fly on autopilot,” said Delore. “They are stripped down racing machines with very few instruments to assist the pilot. In cloud the pilot has about 180 seconds before losing control.”Delore had to make a snap decision. Pull out and forgo the record or fly into the cloud. “We knew there were no mountains, we had heaps of altitude and I could use the gyro to keep us on a horizontal plane.” Decision made.
They flew the last 14 km blind, aiming for an invisible column of air with a radius of 500 m and a vertical height of 1000 m to finish within the legal limits of their start point. “I was aiming upwind slightly because I knew the crosswind would blow us back onto the turn/finish point.”
Fossett’s usual crisp instructions became more tense. “He could see we were not actually heading toward the turn point but didn’t realise I was relying on the drift of the wind to bring us into the target. So he was yelling out to me, ‘You are too far right. You are too far right.’ And of course all the time we were drifting left towards the finish. For the last 2.5 km we were right on the minimum altitude. Directly under the finish point we were 30 ft (9 m) too low and I pulled the stick hard back—which bled our speed from 110 knots right back to stall speed—to climb to the finish point. We used every last bit of momentum to climb, then fell out of the sky, but that didn’t matter as we had plenty of altitude to recover. As it turned out we were within 60 m of the finish point and 13 ft above the minimum altitude, which was almost perfect.”Their average airspeed over the full 1000 km was 166 kph, which beat the old record by a good margin.
Most soaring in New Zealand isn’t about setting records. It’s about the exhilaration of flying and adventure. Before meeting Gavin Wills, the head instructor at GlideOmarama.com, my limits were all terra firma-based. But after spending a few days sitting in on his lectures and listening to the excited patter of returning pilots, I was keen to fly.
In due course I clambered into the cockpit of a Duo Discus sailplane at the eastern end of the Omarama airfield with instructor Dieter Betz. With a roar of engines and in a cloud of dust, the tow plane—a Piper Cub surged forward. Our wing runner released us and the cockpit rolled slightly as we hurtled along the airstrip, wing tips threatening to touch the grass. A hundred metres down the runway, the wings lifted, our wheels left the ground and the tow plane became airborne. Over the radio Betz instructed the pilot, “Take us to Horrible Annie.” Not a destination to inspire confidence, I thought.
At 500 ft (152 m) Betz announced, “You have control.” With as much confidence as I could muster, I responded, “I have control.” Saying it made me feel better, until a strong sinking crosswind bumped us sideways and downwards. My response was automatic and instantaneous: I pulled back on the stick and pushed left rudder. But I overcompensated and the glider began to porpoise. It was about then that I was hoping to hear the soothing voice of Betz say, “I have control,” but it didn’t come. I felt his presence when I moved the stick and rudders, which gave me some reassurance, but he didn’t instruct me to relinquish control. After a few heart-stopping moments we again sat neatly in line with the tow, giving me an almost unreal sense of satisfaction.
At 2500 ft (762 m), beside the western face of Mt Horrible, Betz announced to the tow pilot, “Releasing,” and instructed me, “Pull the yellow cord.” I did as he said. A thump from beneath signalled the detachment of our lifeline to the Piper Cub. We banked left and the tow plane dropped away right.
Betz took control and twisted the glider into a steep turn. Remarkably, instead of descending we started climbing. Above one of Horrible’s ridges a welcome bubble of warm rising air embraced us. It was amazing. I heard the wonderful trill of the variometer indicating lift. We were soaring along the side of a mountain 2000 ft (610 m) below its summit. Just 300 ft (91 m) below us was one of its lower ridges, and we were hanging on our side, no engine, spiralling upward in figure eights. In no time at all we had climbed 1000 ft (305 m) on the warm air. Just as I was beginning to feel comfortable, I again heard those intimidating words, “You have control.”
I had been following the movements of the stick and the rudder as Betz had been climbing, so I had some notion of what I needed to do. Keep one wing down, turn in tight circles, roll with the stick hard over, maintain the horizon, use the rudder to maintain forward position—and the more rapid the trill from the variometer the better.
What makes flying different from driving a car or riding a bike is the third dimension. On the ground all you can do is go forward or back, left or right. In the air you can also go up or down. I couldn’t quite get to grips with that. The horizon is liable to change very disconcertingly and your brain takes a while to catch up. But there was no suppressing my excitement. I was constantly talking to myself: “Watch the horizon. Keep the nose up? Pull up? Go down? Too much. Good. Slow down. Speed up. Sinking.” The theory you learned and the stuff you picked up in conversations on the ground seemed logical and easy enough to assimilate. But in the air everything was different; nothing was straightforward. The main thing that stuck was Wills’ golden rule: “Don’t hit the hill.”After a time my brain acclimatised to being pitched on its side as the plane spiralled upwards. But I still had difficulty keeping the nose up while circling in a thermal.
Weather conditions in the Omarama Basin were changing, and the portents indicated a wave might be about to form. Sure enough, when I woke at 4 a.m. one morning, the sky was stacked with wave clouds. A few hours later and I was back in the Duo Discus with instructor Lemmy Tanner, a mountain thermal lifting us up to cloud base. When winds become extreme, waves can overdevelop and collapse like breaking surf, with unpleasant consequences for aircraft. This day the winds were strong—about 30 knots—but not extreme, so we were hoping for an eventful but not alarming flight.
A wave is usually marked by several distinct cloud forms. Cloud often caps the summits of the mountains, indicating the start of a wave. Straggly, whiskery clouds form and die where thermals rise against the leading edge of the lower part of the wave. Above these, bulkier cumulus clouds guard entry into the wave. The whisker clouds were our target.
According to Wills, a pilot must move through several kinds of lift in order to climb into a wave. Approaching our thermal, Tanner and I began positioning ourselves for so-called rotor lift. Rotor behaves like a large water wheel, with ascending air on the upstroke and rapidly descending air on the downstroke. There are no signposts telling you where to go, and often it’s a case of “suck it and see”. Sometimes luck is on your side. Other times, turbulent rotor bubbles suck you in, swill you around, then spit you out.
After sampling several whisker clouds and being ejected by each, we decided to descend and try again lower down. Tanner identified the rotor–wave interface, and once more we flew into wild turbulence, but instead of the sledgehammer punch of rotor-bubbles and the squawk of descent from the variometer, we were hoisted skywards to the music of rapid ascent. The wind speed increased and our climb rate more than doubled, while the twist and thump of turbulence gave way to the smooth stability of wave sailing. In a very short time, the powerful upward surge had borne us from our entry point at 8000 ft (2440 m) to the crest of the wave at 24,000 ft (7320 m). Still new to the game, I was astonished that this was possible.
We were climbing in a wave triggered by the Ohau Range, but this wouldn’t take us to Mount Cook, our declared destination. Once we had gained sufficient altitude we needed to hop from the Ohau to the Ben Ohau wave. Above Lake Ohau Tanner pointed the nose of the Duo Discus towards the distant water and we accelerated to nearly 200 kph. Diving imparts enough speed to effect a rapid transit through the sinking air in the descending part of the wave.
Inside the cockpit the view changed from pleasant mountain panorama to steely lake and schist rushing towards us. In a matter of seconds we lost 7000 ft (2135 m), with the variometer cackling our death knell. To my relief we hit the rising air of the Ben Ohau wave at a little over 13,000 ft (3965 m).
From there we soared all the way to Mount Cook, gaining height until we had nearly doubled our altitude. We were so far above the mountain that it appeared almost insignificant. I could see from one side of New Zealand to the other while gazing down at the grand traverse of Mount Cook. And we had used the forces of nature rather than internal combustion to get there, knowledge of the wind rather than the muscle of fuel.