FAA ready to test Aspen airport equipment again
November 2, 2010
ASPEN – The Federal Aviation Administration plans to test a directional aid located atop Aspen Mountain again Wednesday with the hopes of putting the equipment back in service to signal pilots flying into the Aspen-Pitkin County Airport.
Interference from a power line, and even snowcats, has forced the FAA to make modifications to its project and has turned what was supposed to be a two-week shutdown into one that is now in its fourth week.
The localizer directional aid, at the top of the Buckhorn ski run, has been out of service since Oct. 8, hampering a number of United Express flights, operated between SkyWest, between Denver and Aspen. As of Friday, SkyWest had canceled 63 flights as a result of the localizer repairs.
Returning the equipment to service is a top priority for the FAA, the agency said in a press release issued Tuesday.
The localizer works in tandem with other navigational equipment at the airport. Pilots depend on the LDA signal to execute a missed approach procedure, allowing them to circle back for another attempt to land. Without it, SkyWest has been forced to cancel or divert flights whenever cloud cover forces pilots to use an instrument approach to the airport.
The FAA is replacing the localizer because the old equipment and antenna platform were nearing the end of their service life. The new equipment improves the reliability and quality of the broadcasted signals. In addition, the FAA said, the new platform reduces snow accumulation around the antenna array and improves its all-season reliability.
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The work was timed for the offseason to reduce impacts to commercial air travel, as airlines fly fewer flights in and out of Aspen during the offseason, but off-and-on overcast conditions during the repairs have affected flights.
The $1.5 million project was initially scheduled to be completed by Oct. 21, but the FAA discovered the new, larger antenna array was too close to a power line that feeds facilities on top of the mountain. The problem was discovered during the initial flight test on Oct. 21; Holy Cross Energy subsequently relocated the power line, and an Oct. 29 flight test showed improvement in the “signal integrity,” the FAA said.
“Unfortunately, the improvements were not enough to meet the rigorous FAA safety standards to allow for the system to be returned to service,” the agency said.
A decision was then made to install a shield to prevent the system from being adversely affected by a signal reflection off snowcats grooming the ski run below the antenna. It also shields the array from the power line where it crosses at the bottom of the ski run, below the antenna platform. The shield work was completed on Monday, the FAA said.
The new equipment is more sensitive than the equipment it is replacing, according to the FAA. This allows for a more precise broadcast signal and improved guidance to pilots using the system, but it can also be influenced by various factors, particularly terrain.
The terrain atop the mountain is “very challenging,” with an extreme drop-off in front of the antenna array and rising ground to the west, the FAA said. The agency decided to modify the array to a configuration similar to the one it is replacing, which allows for a more forgiving signal pattern, like the old array, but with state-of-the-art electronics, the agency said.