Finding danger spots in flight

Study aims to make flying into Juneau safer

Posted: Monday, August 06, 2001

Several years ago a commercial jet flying above Juneau hit turbulence so severe it knocked the aircraft on its side.

"It was bumped up so the wings were vertical instead of horizontal," said Al Yates, of the National Center for Atmospheric Research, or NCAR. "That's pretty darn severe."

Researchers at NCAR hope to make such close calls a thing of the past with a $6.7 million appropriation recently approved by the U.S. Senate for Juneau's wind profiling project, launched in 1996 to pinpoint wind hazards bred by the area's mountainous terrain.

Although the project has given pilots a clearer picture of danger spots in Juneau's skies, the extra dollars, if approved by a conference committee, would help make the system more sophisticated, Yates said.

"The intent of the $6.7 million is to continue development of this system into a warning system," said Yates, an engineer who helps run the pilot project funded by the Federal Aviation Administration. "Right now it provides wind information only."

Although anemometers and other sensors in Juneau transmit vital information on wind speed and direction, it's only raw data, said Doug Wahto, a pilot for Alaska Airlines. Pilots have to analyze the numbers to determine the presence of turbulence and wind shear, potentially dangerous phenomena that can cause pilots to lose control of aircraft.

"It's basically a manual system right now," said Wahto, who has worked on the project. "It's not necessarily timely ... you need to look at every individual sensor."

Researchers want to use some of the money for computer software that would analyze the data for pilots and keep a constant vigil for trouble spots. Wahto envisions a system that would automatically detect hazardous wind conditions and sound an immediate advisory to air traffic controllers, who would relay the warning to pilots.

"That advisory could be issued by the controller himself or we could take this one step further and have it automated so it went right into the cockpit," Wahto said.

The benefit is pilots in the area would know immediately when hazards are detected, whereas pilots entering Juneau currently rely on their analysis done 10-15 minutes earlier enough time for conditions to change, he said.

The computer calculations also would be more accurate than the pilot's analysis, said NCAR's Bob Barron, manager of the project.

"We'll have a higher probability of detecting hazardous conditions and a lower false-alarm rate predicting the hazardous conditions," Barron said.

Although Juneau's turbulent skies never have brought down an airliner, the FAA in 1996 closed two departure routes for commercial jets, citing concern over turbulence and sudden wind shifts in the mountains surrounding the airport. The FAA later reopened the routes but with restrictions. Pilots use the wind data to figure out whether they can use the routes given the constraints.

NCAR, a federally-funded research group, has posted the wind data on the Internet at

Kathy Dye can be reached at

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