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Wind And A Prayer

An intimidating place to land aircraft, Alaska's Juneau Airport is being transformed into a laboratory for new technology to aid takeoffs and landings.

March 20, 1997|LEE DYE | SPECIAL TO THE TIMES

JUNEAU, Alaska — Nestled at the foot of several mountain ranges and frequently engulfed in fog and blasted by chaotic winds, Juneau International Airport is being transformed from an intimidating place to land an aircraft into the nation's leading test bed for new airport technology.

The airport, serving Alaska's capital city, is expected to become the first in the world with an integrated system that will give pilots a complete picture of winds and weather conditions from the sea-level landing strip to more than a mile above the mountains next to the airport.

The system includes a network of ground-based wind gauges plus radar "profilers" that will measure winds at higher altitudes, and a satellite navigation system that will pinpoint the position of approaching airliners more accurately than any ground-based system. It is expected to become the model for the rest of the world, and it is being installed her partly because scientists believe that if they can do it here, they can do it anywhere.

A massive field of ice, called the Juneau Icefield, stretches over hundreds of square miles east of the mountains that line the airport. Cold air descending over the mountains picks up speed as it drops toward sea level, just like water spilling over a dam. It hits the ground and washes up the sides of the mountains like water sloshing from a bowl, creating wind currents that can only be described as weird. Wind velocities of more than 100 mph are not uncommon, especially in winter. And it can be calm in one area and howling just a couple of miles away.

The pilot of a small plane found that out the hard way recently. He tried to approach the runway from one direction but encountered tail winds too strong for him to land. So he went around and tried to come in from the other direction, only to find strong tail winds there as well.

"I wouldn't have believed it myself if I hadn't seen it with my own eyes," said David C. Miller, a retired Air Force pilot and manager of the airport. And just as odd, the wind was blowing directly across the runway near its center.

The pilot landed by aiming for the center of the runway and then making a sharp turn into the wind just before his wheels touched down.

Stories like that have made the airport infamous, and they have not always had such a benign ending.

Over a 24-year period, three Juneau-bound aircraft have crashed within 11 miles of one another on a range of mountains less than 30 miles northwest of the airport. There were no survivors.

All three aircraft were receiving erroneous navigational signals that indicated that they had already cleared the rugged Chilkat Mountains, so they descended prematurely. An Alaska Airlines 727 crashed Sept. 4, 1971. On Nov. 12, 1992, a National Guard plane crashed near the same site. And a Lear jet crashed nearby Oct. 22, 1995.

Nearly four years after the 1992 crash, another Alaska Airlines pilot narrowly avoided a disaster. The airliner had just taken off and had made a sharp turn at the end of the runway to avoid the mountains to the south when it was hit by a severe downdraft.

"It got down to about 250 feet before the pilot recovered," Miller said. That put it nearly at treetop level above Douglas Island, and it narrowly cleared the house where Miller now lives.

"It was a very scary incident," he said.

Chiefly because of that near-tragedy, and a growing understanding of wind shear, the Federal Aviation Administration early this year closed down two departure routes out of the Juneau Airport. Since then, numerous flights have been grounded intermittently, further isolating the capital, which can be reached only by air or sea.

That move accelerated efforts in Juneau to upgrade the airport, and it brought in outside sources eager to show that new technology can make any airport much safer.

* The airport used to have only one wind gauge, but now it has installed them throughout the area, even on the tops of the mountains that encircle Juneau. Readings are fed into a computer that provides a complete picture of surface winds throughout the region.

* The National Center for Atmospheric Research in Boulder, Colo., has installed two wind profilers within eight miles of the airport that measure wind velocities from the ground up to 12,000 feet. The profilers are radar systems that point straight up, bouncing signals off particles--such as rain or snow--carried by the winds. The echoes tell scientists which way and how fast the wind is blowing at intervals of 200 feet.

* Alaska Airlines, the only major carrier that serves Juneau, is investing $10 million in receivers for the Global Positioning System that will use the satellites to pinpoint the positions of its aircraft. Ground-based navigational aids, including radar, are far less reliable because of interference from the rugged terrain.

The wind gauges are operational, and the system is one of the most comprehensive ever established at an airport.

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