The FAA is testing new technology designed to reduce the risk of runway accidents at major U.S. airports.

Do you know which aviation accident holds the record for the greatest loss of life? It wasn’t a midair collision or a jumbo jet falling from the sky—it happened on the ground, in the horrendous crash of a KLM 747 and a Pan Am 747 at Tenerife in the Canary Islands on March 27, 1977. The Pan Am plane was taxiing on the airport’s single runway when it was hit during poor visibility by the KLM aircraft, which was in its takeoff roll. Almost 600 people died in the worst example in history of a “runway incursion.”


As commercial air traffic continues its breakneck growth, such scenarios are very much on the minds of safety experts. In response, the FAA is rolling out new technologies designed not only to prevent planes from getting too close to each other on runways, but also to keep them from overshooting the pavement when they land. XX The threat of runway incursions increases exponentially as the number of commercial flights grows. A study in 2000 by Canada’s transportation agency found that an air traffic increase of 20 percent brings with it a 140 percent jump in the risk of runway incursions. The Air Line Pilots Association (ALPA) notes that from 1993 to 1998, air traffic volume in the U.S. grew by just 2.4 percent, but the rate of runway incursions jumped 67 percent. According to the most recent forecast from the Federal Aviation Administration (FAA), U.S. flight operations are expected to increase by 1.4 million per year from now through 2020—the equivalent of adding twice the traffic at Dallas/Forth Worth Airport annually.

Greater awareness

Yet according to Wes Timmons, the FAA’s director of runway safety, the agency reports the number of serious runway incursions in the U.S. (the types most likely to result in an accident) is down 55 percent since 2001. And that’s before the very newest technologies were even deployed. The most significant reason for the decline so far, Timmons says, is “awareness on the parts of pilots and controllers and people operating vehicles on the airport surface.” He explains that the FAA conducted a widespread outreach program in recent years to educate airline and airport personnel about these dangers, and in 2002 created “runway safety action teams” to evaluate airport operations. Those teams have made more than 4,400 safety recommendations to airports, and more than 3,300 of those have been adopted already.

Further improvements are in the works. At 34 major airports, the FAA currently uses a radar-based system called AMASS (Airport Movement Area Safety System) to track all aircraft movements on the ground, and to alert controllers if a plane strays to somewhere it shouldn’t and poses a threat to another aircraft. But ground radar doesn’t work as well in fog and rain, so the FAA is stepping up the technology with a next-generation version called ASDE-X, or Airport Surface Detection Equipment, Model X. ASDE-X relies on both radar and on signals from transponders aboard aircraft, as well as equipped ground vehicles—letting controllers know even in bad weather exactly the location and destination of every aircraft, with automatic alerts of potential conflict. The new system is currently operational at almost a dozen airports, including Milwaukee, Orlando, Providence, Houston Bush Intercontinental, Seattle, St. Louis, Atlanta, Bradley, Louisville, Charlotte and O’Hare.

Bringing pilots into the loop

One drawback of AMASS and ASDE-X: These systems send their alerts to the controllers, who must then warn the pilots of at-risk aircraft by radio. In a report detailing its wish list of “most wanted improvements” for the aviation industry, the National Transportation Safety Board (NTSB) says it would be better if situational alerts were routed directly to the cockpit instead. The issue is one of reaction time,” explained an NTSB spokesperson. “Simulations of AMASS performance using data from actual incursions show that alerts may occur as little as 8 to 11 seconds before a potential collision…. Unless there is a system in place to positively control ground movements of all aircraft, with direct warnings to pilots, the potential for this type of disaster will remain high.”

The FAA’s Timmons agrees. “We think that is a more complete solution,” he said, and the agency has a few ideas up its sleeve. At Dallas/Fort Worth and San Diego airports, the FAA is testing a new system of runway status lights. These are implanted in the runway surface and integrated into the ASDE system, operating like traffic lights for pilots. “The key is that as soon as the controller is alerted, the pilot would also see an alert” from the status lights, Timmons describes. In a similar new system, called FAROS (Final Approach Runway Occupancy Signal), the lights are aimed upward at incoming aircraft, and will then flash to warn them away from landing if the system detects a potential conflict on the runway.
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Runway Risk: The Dangers of Debris
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The next stage, already being tested, integrates satellite-based GPS technology into the ASDE-X loop, giving both controllers and pilots of properly equipped planes a real-time display of all ground traffic on the airport surface. This technology, called ADS-B (Automatic Dependent Surveillance-Broadcast), is the backbone of the FAA’s grand plan to overhaul air traffic control in coming years. A new nationwide navigational system, called NextGen, will replace the decades-old radar-based technology currently in use with satellite-based GPS systems in all aircraft. Technology developed by Honeywell and Sensis blends ADS-B data into the ASDE-X system and gives pilots an audible alert in the cockpit if a dangerous runway incursion situation is developing.

ASDE-X is slated for deployment at 35 U.S. airports, and runway status lights are planned for 20. One problem: ASDE-X and its add-ons are “very expensive technology,” says Timmons, so the FAA is also testing less comprehensive ground surveillance systems at Spokane Airport. “It will be kind of a low-cost version of ASDE-X for less busy airports,” Timmons explains.

Low-tech solutions are also part of the program. At the FAA’s urging, the nation’s 75 largest airports are repainting the markings on their runways to keep pilots out of danger zones; most significantly, by adding bold yellow-and-black markings on taxiways as they approach intersections with active runways. The FAA has also ordered the use of new paint with tiny glass beads in it, which will make the markings more reflective and easy to spot at night.

Runway excursions

Finally, to keep landing aircraft from overshooting the end of a runway—the dreaded runway “excursion”—airports are installing a new kind of pavement known as EMAS (Engineered Material Arresting System). Also called cellular concrete, this material will collapse under the weight of a large aircraft, bringing it to a safe stop—just like trying to ride a bicycle in the sand. It’s already been installed at the ends of 25 runways at 18 airports, according to Rick Marinelli, manager of the FAA’s airport engineering division. And it’s already working: “Three aircraft have been arrested at Kennedy Airport so far, and one at Greenville, South Carolina,” he says. Even the technology of runway surfaces is being reexamined for safety improvements, notes Marinelli. Runways use grooved surfaces to drain moisture, and he says the FAA is testing “a new shape of groove that’s trapezoidal instead of rectangular. It promises to be more efficient in removing water.”

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JIM GLAB is a freelance writer based in Colorado.