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A fundamental shift to satellite-based tools would require a monumental effort to achieve consensus among pilots, controllers and regulators. How could consensus be achieved? In air traffic control, “things tend to be reactive rather than proactive, and that’s probably what’s going to happen here,” says Jim Kuchar, associate professor of aeronautics and astronautics at MIT. “A systemwide change is either going to occur because of a major congestion problem, or because efforts like UPS make it more attractive. If UPS gets this thing working and it shows all these benefits, maybe others will say, ‘we’ll take another look at this.’”

That second look, however, may be slow in coming. Four years ago, United Airlines pilot Rocky Stone proposed using the new satellite-based technology to fight congestion by allowing paired landings during poor visibility at the notoriously fog-bound San Francisco airport, where the runways are a whisker-close 250 meters apart. But the idea proved impractical in the short term, says Dave Jones, who directs United’s efforts to improve efficiency at its San Francisco hub. To implement the strategy, United realized it would need Boeing and Airbus to approve new cockpit displays, pilots and controllers to accept them, and the FAA to certify equipment and applications. And even if United had installed the system, its airplanes would still have had to get in line with other airplanes lacking the technology. In the face of these obstacles, the airline shelved the plan and is exploring advanced radar-based tools and procedures instead.

United’s experience illustrated a fundamental difficulty in implementing this new technology: it’s an “all or nothing” proposition. Unless all airplanes around a given airport are equipped with it, the system can’t be relied upon for spacing, collision avoidance or much else. “There’s got to be a whole architecture of the airspace that everybody has got to agree to,” says Robert Rosen of NASA’s Ames Research Center in Moffett Field, CA. “None of that is in place today. It [ADS-B] is kind of like a piece of the puzzle, and it may even be a cornerstone of it. But having it in place is still far from having solved many of our problems.”

The case for satellite tools is far more compelling where radar infrastructure is spotty or nonexistent-and where the safety benefits are obvious. One such place is Alaska’s 260,000 square kilometer Yukon-Kuskokwim Delta region, where small-airplane deliveries and transportation are an essential way of life-and death. Much of Alaska has no radar coverage, no air traffic control towers and no paved runways (gravel airstrips are a luxury), making the area more like remote regions of Africa or China than the lower 48 states. The 1990s saw an average of one aircraft accident in Alaska every other day, including 186 fatal crashes leaving 398 people dead. During that decade, Alaska accounted for 37 percent of the nation’s total aircraft accidents and 20 percent of total air-crash deaths.

In 1998 this carnage prompted Congress to appropriate $11 million to install new equipment in 155 small airplanes in Alaska. UPS Aviation Technologies provided the avionics, and now the GPS-based system is being used by Anchorage-based air traffic controllers to guide small aircraft in the remote, marshy delta. And while radar-devoid countries like Australia and even Mongolia are starting to deploy satellite air-traffic tools, the Alaskan region is the first place in the United States-and the only one in the foreseeable future-to move to 100 percent satellite-based air traffic control. (In the UPS experiment in Louisville, radar would still guide aircraft to and from airports. The satellite tools would only aid approach and departure spacing.)

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