A low-level wind-shear detection program that soon will be in place at the Juneau Airport will be the first of its kind in Alaska, and one of 10 in the United States, Federal Aviation Administration officials said.
"There's a lot of unique air movement in this terrain," said Steve Turner, air traffic manager for the FAA at the airport. "Weather systems come through here and get mixed up in our channels and terrain, and the icefield has an effect on that. ... We know it causes a lot of disturbed air in this area."
So the FAA is working to set up a low-level wind shear alert system for the airport. Wind shear, a meteorological phenomenon characterized by rapidly changing wind currents, can cause serious problems for pilots landing or taking off from Juneau, Turner said.
Although wind shear can happen at cruising altitude - passengers often feel a sudden drop in the plane's altitude caused by the event - they are much more dangerous when they occur during takeoffs or landings, said Marcella Meador, a team leader at the FAA's Aeronautical Center in Oklahoma City.
Engineers in her office designed, developed and helped install the Juneau system and others around the country, she said.
A temporary tower on Egan Drive and another on Crazy Horse Drive hold three wind-speed and direction measurement devices, which send signals to the Juneau Airport. Monitors already in place on the runway and on Peterson Hill between Engineer's Cutoff and Fritz Cove Road also send signals and allow air traffic control to warn pilots about dangerous conditions, Turner said.
"It just alerts the pilot that there's an event happening on your takeoff or approach that you need to know about," he said. "Then it's up to the pilot to make a decision on what to do."
Before the wind shear alert system was installed, air traffic controllers knew about wind shears only after pilots encountered sudden changes in wind while landing or taking off, Turner said.
When the temporary towers come down on Feb. 11, the FAA hopes to erect a permanent tower on city land near the Southeast Alaska Food Bank on Crazy Horse Drive.
Steve Gilbertson, lands and resources manager for the city, recommended to the Juneau Assembly Lands Committee early this year that the city grant the FAA a 20-year lease on the property. The city will not charge the FAA for the lease.
"We have a lot of cooperative efforts with the FAA to make the airport better," said Gilbertson. "It's a city-run airport, so it's really to our benefit to do that."
The nine other airports in the United States with the FAA detection system have Doppler radar to detect microbursts, a particularly strong form of wind shear. The systems have a 99 percent detection rate for wind shear and microbursts, Meador said.
"Juneau doesn't have radar or a place radar would work because of the close mountains," she said.