In the lee of giants
Flying high on mountain waves
Originally appeared in AOPA Pilot magazine.
BY NATHAN A. FERGUSON
Strapped in a fiberglass glider, the pressure demand oxygen system is forcing air into our lungs. We are climbing on the lee side of the snow-capped Sierra Nevada at the end of a 200-foot tow rope and a question comes to my mind as we're heading for rotor, an area of massive turbulence: When do I release?
Normally, this isn't a difficult question. There are three rules at Minden, Nevada, the current Mecca of mountain wave soaring. You should yank the release knob if either the towplane or the glider rolls inverted; the tow pilot and the glider pilot get so mishmashed in the horizontal tornado that they end up looking at each other; or when you connect with glass-smooth mountain wave — what Minden is famous for.
On a mid-April morning, as the melting snow is trickling down the peaks and the ski resorts are closing, we're flying a Grob 103, a type of glider I have a lot of faith in from many hours of flying one above the mountains in Utah. Andrew McFall, Soar Minden's operations manager, sits in the rear seat. He is a veteran of some 25,000 glider flights and he has that construction-worker tan from spending much of his life under a plastic canopy. Most of the time the rotor here is benign, but it has been known to generate forces of plus or minus 15 Gs. "There are probably three days a year that it will knock your teeth out," McFall says. "You have to attack rotor with a certain amount of fear." He ought to know. He's been rolled over twice in the towplane but never in a glider. Tow pilots try to tow above and perpendicular to the rotor so that the glider pitches instead of rolls. Sometimes you can see the air churning where rotor usually resides at the mountain-peak level, but it also likes to move around. It acts as a gateway to the big lift. The location of the rotor is established on the first flight of the day, or what McFall calls the test flight. Last year two days were deemed too wild to fly, even for Minden.
As we near the rotor zone, McFall tells me to forget about maintaining precise formation and concentrate on keeping the towplane in sight. A key is to keep slack out of the towline. If things go awry, loops can form and work their way back, threatening to squeeze the life out of the glider like a boa constrictor. My left hand is on the dive brake lever to slow the slippery craft and carefully take out the slack if things get interesting. Surprisingly, we only get knocked around slightly, not like having your shins battered by the bottom of the instrument panel as your feet fly off the rudder pedals in rough air. When we connect with the wave, it's unmistakable and so perfectly smooth. There's no feeling, no sudden rush in airspeed, just the instruments indicating a climb. No question. It's time to release.
We head toward Heavenly Valley Ski Resort and climb through a hole in the clouds, trying to remain within the lift band. When low in wave you have to circle or make turns back and forth to stay above a reference point on the ground until you get high enough and the winds aloft equalize your forward speed. Climbing at 400 to 500 fpm — weak for wave — we quickly make our way through 12,000 feet when McFall notices something peculiar. The clouds are closing — our hole, our escape hatch, is disappearing. I open the dive brakes, point the nose down, and descend at the optimum rate. We shoot back through it just as it closes.
McFall's concern is well founded. He had been caught above the gray abyss before when he was with a student. (Gliders normally don't pack blind-flying equipment.) They used the standard time-tested procedure to get down: Call air traffic control, trim for 50 knots, put the glide in a 10-degree bank, hold on to the shoulder straps, and stay off the controls. Since the controllers were able to get a radar paint, they gave McFall updates on his position so he would know where he was when they broke out. It worked perfectly. McFall is careful not to let this happen to us, though.
I have come to Minden to learn about these powerful forces that can bring down even the largest of airliners, hoping the wave will carry me up to 20,000 or 30,000 feet. For centuries mountain waves were shrouded in mystery as people gazed toward the heavens at eerie lenticular clouds that remained stationary above the peaks unlike other clouds that made smooth tracks across the sky. Gliders were the first to fully explore this phenomenon in a scientific way. They say that when you get high enough over the Carson Valley you can see the Pacific Ocean glistening in the distance some 200 miles away. It becomes all the more alluring.
The Sierra Nevada is an old mountain range that has been shaped over time by high winds into an aerodynamic structure like the top half of an airfoil. The range obstructs the wind — similar to a large boulder in a fast-moving stream — and sends it moving in a wavelike manner on the lee side of the range. Ideally, a temperature inversion layer forms over the valley and the winds reach 25 knots at 10,000 feet, then pick up to 100 knots from the west at 30,000 feet. If the wind blows from roughly the same direction at different levels in a stable atmosphere, the wave will oscillate between the inversion layer and the jet stream. Glider pilots ride the wave crests while avoiding the tremendous downdrafts in between. The wave season typically starts in the fall and runs through spring. Just to show how powerful waves can be, McFall, while shooting a video about the sport last year, shut down the engine in a Piper Pawnee towplane and was able to climb at 400 fpm.
Soar Minden is one of two glider businesses at Minden-Tahoe Airport. There is a buzz of foreign accents on the ramp, around the glider trailers, and over the airwaves. On a board in Soar Minden's operations building under the heading "Great Soaring Flights" Ed Peerens entered his 1988 field record set by taking a Grob 103 to 45,000 feet: "OVR Jack's Valley 100 percent O2 whole FLT," he wrote. And on April Fools' Day this year Steven L. Thornton gained 17,800 feet from his release at 9,000 feet: "Blown off tow in rotor, climbed in and notched in rotor — a really memorable flight," he wrote. This is no joke.
At 81, Hod Taylor still gives glider rides and lives for soaring. In 1967 he took a Standard Austria up to 42,800 feet over Colorado. Taylor says he was just "goofing off." Considering his age and susceptibility to decompression sickness, his personal limit is now 30,000 feet. "I need a fix every once in a while," he says. Having experienced everything firsthand during 10,000 hours in gliders and 28,000 in airplanes, he's the obligatory old man at the airport who can sense disasters coming, representing an important body of knowledge that is rapidly disappearing from the soaring scene.
While hoping the wave will return, even though the timing has been off all year, I prepare for some lower-altitude thermal soaring in a single-seat Grob 102 as the cumulus cotton balls are starting to pop all over the valley in the unstable atmosphere — the antihero, so to speak, of wave development. Although Minden is known for going high in wave, it's also an excellent place for thermal soaring once the snow melts, the valley heats up, and the cloud bases rise with the burgeoning summer. Taylor is on the flight line, freely offering wisdom, wearing Nomex fighter-pilot gloves to keep his hands from being further ruined by the Nevada sun. Forget your oxygen mask? Just suck through the oxygen tube if you get high. No parachute? That's OK, you'll just be more vigilant in the pattern looking for traffic. You're not going to wear that hat, are you? The brim is too wide; you might miss a speck of sky that turns out to contain a fast-moving jet.
Minden has three adjacent wave windows — west, central, and east. Gliders are free to climb to 17,999 feet without permission from controllers. When pilots in Minden are nearing that ceiling, Soar Minden calls Oakland Center and asks to have one of the windows opened. Once it's opened, all the gliders are cleared. Generally, controllers give the gliders higher ceilings as needed. The window remains open unless things get backed up in the San Francisco Bay Area because of weather. When the wave is cooking in Minden, the small airplane pilots stay on the ground to avoid the high winds and turbulence, while commuter airline traffic shifts to the east. Many controllers have taken advantage of Soar Minden's open invitation that allows them to go on free wave flights. For high-speed cross-country flights in wave that have taken glider pilots nearly to Mexico from here, they stay below 18,000 feet so that they won't need clearances. Experienced wave pilots learn to read the clouds and can jump from one wave system to another. McFall calls it "following the invisible highway."
As with most endeavors, the knowledge behind wave soaring builds on itself and the legends are not forgotten. Hans Deutschmann and Wolf Hirth discovered waves by accident in 1933 while soaring in the lee of Germany's Riesengebirge Mountains. Four years later, Joachim Kuettner, flying an open-cockpit Rhone Buzzard glider, broke a world record by climbing to 22,300 feet. Kuettner was hardly dressed for the conditions and narrowly survived frostbite with temperatures of 50 degrees Fahrenheit below zero. Not only did he experience the power of waves, further igniting his curiosity, he was an early survivor of oxygen deprivation. His fingers turned blue and he saw two suns, according to the book Exploring the Monster by Robert F. Whelan. Kuettner later left Germany to pursue his passion as a meteorologist in the United States. He would assume the role of project scientist for the Air Force-sponsored Sierra Wave Project, the first comprehensive study of mountain waves in Bishop, California. Glider pilots at that time had ventured into thunderheads, but the turbulence associated with rotor was found to be worse. Paul MacCready Jr., world champion, a three-time U.S. national soaring champion, and pioneer of human and solar-powered flight, was flying in Bishop before the Sierra Wave Project got under way. In a phone interview, MacCready reflected on one flight where he saw the wings on his Orlik II glider bend 6 feet from a brief 8-G encounter.
In 1951 and 1952 a small group, including such soaring legends as Bob Symons and John Robinson, modified two Pratt-Read gliders and routinely exceeded 40,000 feet as part of the project. They literally gave meaning to the words applied science. The pilots flew in a frigid, unpressurized environment in meteorological conditions that were not fully understood. But in a follow-up popularly called the Jet Stream Project, where glider pilots studied the jet stream with the assistance of B-29 and B-47 bombers, Larry Edgar found out what rotor can do. On April 25, 1955, his glider quickly disintegrated around him at 17,000 feet as he tried to avoid a swelling roll cloud. Then things became quiet. All he heard was wind noise, and he felt as if he were suspended in space, but he couldn't see because of the G forces, he wrote in Soaring magazine shortly after the experience. He pulled the ripcord and started to worry about being pulled back up. He had lost his helmet, boots, gloves, and oxygen mask, and the hose was broken off of his bailout oxygen bottle. As his vision slowly came back in one eye, he saw pieces of fabric and plywood from the Pratt-Read being carried up past him, disappearing in the roll cloud.
Miraculously, he survived the parachute landing without breaking any bones and fully recovered. As Whelan pointed out in his book, doctors determined that Edgar experienced a force of 20 negative Gs for 0.4 seconds in order to induce the damage to his eyes. While this event punctuated the power of rotor and raised awareness, it also gave scientists data to further explain the way waves function. They later determined that Edgar had experienced a rare kind of rotor where the wave dissipates all of its energy in one horrific oscillation.
Besides the risks of severe rotor encounters, any time a glider pilot ventures past 30,000 feet the danger increases dramatically. All you have to do is the simple math to arrive at the potential conclusions. At 35,000 feet the FAA figures the pilot has 30 to 45 seconds to react coherently without oxygen. At 45,000 feet the time of useful consciousness is more like five to 15 seconds. Assuming there is an oxygen failure and your glider has, say, a maximum descent rate of 2,000 feet per minute, you won't get anywhere near a safe altitude in time. That's where the bailout bottle or a backup oxygen system comes in handy, as long as you notice the failure immediately and can react before the narrow window slams shut. If that's not enough, at these altitudes the maximum speed at which the glider falls apart and the minimum speed at which it stops flying come together in the thin air, creating a narrow edge the glider pilots have to ride. They call it the coffin corner.
The forecast continues to look less conducive for wave development over the next couple of days, and I begin to realize that my initial contact with the wave might be all that I'll see. After chasing some hawks and other gliders around the valley, I pay a visit to High Country Soaring across the street from Soar Minden. Mike Bradford, a regular who sits in the office, owns a casino but realizes extreme wave soaring can be a gamble where the odds are in favor of the house. Once when he was at 38,800 feet he noticed his friend in the rear seat was unconscious because the oxygen mask was leaking around his beard and they were at the limits of the diluter demand oxygen system. They descended to 25,000 and his friend went into convulsions. At 14,000 he was semiconscious. After they landed the man was groggy for hours and Bradford said his friend now has slight memory problems. Given the risks and cold temperatures, Bradford only goes wave soaring once a year.
Yet the statistics bode well for wave pilots who care to wager. A review of NTSB accident reports back to 1983 showed no fatalities that were attributed to waves. Besides Edgar's famous in-flight breakup, there was one death during but not associated with the Sierra Wave Project and that was because of an oxygen problem. But there's another factor that Bradford brings up — the potential damage to expensive racing gliders. When wave pilots want to come down, they come down fast, and the gel coat finish cools at a faster rate than the fiberglass, eventually causing cracking. While Soar Minden and High Country Soaring have brought a degree of professionalism and added safety to the area by offering wave checkouts, they are also the ones who end up with the expensive repair bills from pilots who don't want to risk their own craft.
Outside High Country's hangar is a huge box, containing a Stemme glider fresh from the factory, owned by global adventurer Steve Fossett — another regular. Fossett himself plans to leave a mark in the world of soaring by going after the altitude record that currently stands at 49,009 feet, set by Robert Harris in 1986. To take things to the next level requires a quantum leap in technology and expense. An ambitious team with help from NASA is planning to build a glider capable of soaring to the far reaches of the stratosphere, possibly beyond 100,000 feet. The project was dreamed up by retired test pilot Einer Enevoldson after high-altitude research confirmed the existence of stratospheric waves. The project's goal is purely scientific; to figure out the complex atmosphere by making the turbulent transition from mountain to stratospheric waves, while Fossett's record attempt will remain a sidebar to the mission. Called Perlan, the 95-foot-wingspan glider is named after rare mother-of-pearl clouds. It will require spacesuits (the team has acquired five from the Air Force used in the SR-71 and U-2 programs), an autopilot to keep the glider on course in the thin air, and a drag chute to allow it to descend to a lower altitude so that it can regain control if it gets upset by turbulence. Fossett is putting up funding and will act as a pilot along with Enevoldson for the first phase. The team has modified an existing two-place Flugzeugbau 505M glider and will use it to study stratospheric waves over either New Zealand or Sweden. The glider has been outfitted with a 24-hour oxygen supply and a full array of avionics. The team hopes that by drumming up enough attention, it will ensure funding for Perlan.
For the past year Fossett has been learning about mountain waves over the Sierra Nevada by flying with Carl Herold, known locally as "Mr. Wave." Herold probably has more wave cross-country time than any other pilot in the world and has been conducting wave camps for decades. A retired aerospace engineer, Herold once managed an average groundspeed of 190 knots in high winds while flying a glider from Mojave, California, to Minden. He also is no stranger to 40,000 feet and believes he has personally experienced stratospheric waves. Herold flies with a transponder in his Schempp-Hirth Nimbus 3D glider so that he can show up on radar and has no problem getting block altitude assignments from controllers when he's not in wave windows. Besides training Fossett, Herold is specializing in avionics and aircraft controls on the Perlan project. "Steve's not a daredevil. He really puts the faith in the people he's working with to fly safely," Herold says.
After five days of waiting and hoping, the wave doesn't come back. As I head from Reno to Las Vegas on an airliner, conforming to the seat in a puddle of disappointment, we cruise above 30,000 feet, precisely where I had wanted to be in a glider. The stories, the scientific discoveries that lay ahead, the brief meeting with the powerful wave intrigues me even more as I gaze out the window at the inhospitable environment. But as I look around at the other passengers I realize they have no idea that engineless craft have been even higher than this. As Herold, who occasionally uses mathematical terms to describe such things as cumulus clouds, puts it, "People don't know how much energy is up there."
My work here is not done. Minden, I shall see you again.
Originally appeared in AOPA Pilot magazine. Photos by Nathan A. Ferguson.