Friday, May 4, 2012

Glider Pilots Riding Mountain Waves to Over 20,000 Feet Today

Glider Pilots Riding Mountain Waves to Over 20,000 Feet Today:

Photo: Gordon Boettger
Update 4:48pm ET: Weather conditions deteriorated  forcing the flight to end early today. The pilots landed at Joslin Field near Twin Falls in southern Idaho.
Right now, somewhere over northern Nevada, planes are being told by air traffic controllers to keep an eye out for a small, two-seat glider. The unpowered airplane is piloted by 44-year-old Gordon Boettger and the good news for the big jets in the area is that the sailplane pilot has a radio on board and is in communication with air traffic control as well. Riding atmospheric phenomena known as mountain waves, Boettger will spend much of the time at more than 20,000 feet and even higher.
If all goes according to plan today, Boettger and his co-pilot, 79-year-old Hugh Bennett, will fly nearly 1,000 miles simply by using lift provided by the rising air, and speed provided by the jet stream. He departed his home airport at Minden, Nevada, on the eastern slope of the Sierra Nevada mountains just after 5 a.m. local time, and plans to land somewhere in the upper Midwest before sunset, according to his wife, Melissa.
“He’s been wanting to go all the way to the Dakotas,” she said by phone from their Nevada home. “His biggest passion is going downwind. He’s been waiting for good weather to do this.”
The wait for the right conditions can be a long one, according to Boettger. She says there may only be two or three days a year when the winds and other weather conditions permit such a flight. On Tuesday, Boettger and Bennett made an attempt for the long flight to the Dakotas but had to abandon their plans when the lift wasn’t sufficient to get them above 20,000 feet. Conditions often change during the flight and can force changes after weeks of planning.
Just after 10 a.m. PDT today, Boettger encountered a wall of clouds over Winnemucca, Nevada, and was forced south, looking for an open route to the east. As of 11:45 a.m. PDT, the pair is flying Bennett’s German built Schempp-Hirth Duo Discus sailplane at speeds over 140 miles per hour above Wells, Nevada. Bundled in down suits designed for high-altitude mountain climbing and breathing oxygen from small tanks carried onboard (Boettger is pictured above during a previous high altitude flight), they are nearly seven hours into their flight.

All sailplane pilots must use some sort of rising air to stay aloft after being towed into the sky by a powered airplane, or in the case of some sailplanes, with a small “self-launch” motor that gets them airborne. Typically, sailplane pilots search for the invisible rising columns of air known as thermals caused by the sun warming a parcel of air near the ground. Once that warm air is heated enough relative to the surrounding air, it begins to rise and can carry everything from dust and small pieces of garbage, to hawks, eagles and sailplanes with it as it climbs through the atmosphere.
Riding thermals can only get you so high. Eventually the warm rising air cools and matches the temperature of the air surrounding it. At this point the thermal stops rising and often forms one of the classic cotton ball-like cumulus clouds that can fill a summer sky. Pilots will circle in one thermal until it stops, then glide while losing altitude until they can find the next one to climb again.

Boettger (in red) and Bennett just before their early departure this morning. Photo: Fred LaSor
Another source of rising air is known as ridge lift when a wind blows over a ridge or mountain carrying the air – and sailplanes – upward. But for sailplane pilots who really want to fly high, they must rely on an extreme version of ridge lift known as mountain waves to get them into the higher altitudes. A mountain wave forms when strong winds blow across a mountain range. As the wind encounters the mountains it is forced upward, a phenomenon known as orographic lifting. This air that is forced upward can continue its upward trajectory for tens of thousands of feet above the mountain range on the downwind side of the peaks. Unlike the puffy cumulus clouds that mark the top of a thermal, mountain waves are often spotted by the presence of the UFO-like lenticular clouds.
Most record-setting flights in gliders take advantage of mountain waves for a constant source of lift. Last year Gordon Boettger and Hugh Bennett set a U.S. record flying more than 1,300 miles while riding mountain waves over the Sierra Nevada mountains. The flight is also the longest flight in the northern hemisphere. The world record flight took place over the Andes mountains in Argentina and covered more 1,800 miles.
Boettger is no stranger to flying at high altitudes, his day job is as a captain for FedEx flying MD-11 jumbo jets. His wife Melissa says his next big goal is to try and ride a mountain wave for more than a day, “he wants to do an all-nighter.”
First he and Bennett will have to keep riding his current wave eastward to his planned destination of Rapid City, South Dakota, later today. Their progress can be followed on Flight Aware and on Spot.

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