Government/Military Trends
New Technology Inaugurates New Era in Aviation Safety - Marc Narkus-Kramer, MITRE Corporation, Reviews Implications of ADS-B
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One of the most innovative advancements in air traffic control tracking technology since the advent of radar, Automatic Dependent Surveillance-Broadcast (ADS-B), promises to enhance the efficiency and safety of the National Airspace System. ADS-B, which relies on satellite-based Global Positioning System (GPS) technologies, will also help increase capacity at hub airports.
Meet Marc Narkus-Kramer, a physicist who has been working with The MITRE Corporation's Center for Advanced Aviation System Development (CAASD) for some 20 years. A not-for-profit organization working in the public interest, MITRE has partnered with the government to combine expertise in aviation system design and management. Narkus-Kramer, who is currently working in the air traffic control area, has been focusing on communication and broadcast services, which includes ADS-B. "ADS-B is a revolutionary technology," he says, "and it will take many years to completely implement. But it will change the aviation industry significantly."
What will ADS-B do?
ADS-B is a situational awareness tool for pilots, giving them in the cockpit much of the same information now only seen by air traffic controllers. Providing this information in the cockpit will enable the controller and the pilot to manage traffic more efficiently together. For the pilot, it can provide a previously unavailable picture of other nearby aircraft and vehicles on the surface. For controllers, it can provide a more accurate situational display of aircraft position and intent, especially in non-radar areas.
How does it work?
Unlike radar, which works by bouncing radio waves off of airborne targets and then interpreting the reflected signal, ADS-B relies on the satellite-based global positioning system. Each ADS-B equipped aircraft broadcasts its precise position in space, via a digital datalink along with other data, including airspeed, altitude, and whether the aircraft is turning, climbing or descending. ADS-B also works at low altitudes and is effective in remote areas or in mountainous terrain where there is limited or no radar coverage. With this technology, the position of an aircraft or any other ADS-B equipped vehicle (a snow plow for instance) can be broadcast to other pilots, controllers, and personnel who manage airport gates, surface, and vehicle movement.
Current Projects
There are two major ADS-B projects underway in the U. S., both of them involving the Federal Aviation Administration (FAA) and CAASD as participants or sponsors. The Ohio Valley demonstration is evaluating ADS-B equipment and procedures in large transport category jets operating at hub airports in the Midwest. Here, ADS-B has already been evaluated for reducing space between aircraft on landing and departure, and increasing situational awareness on the runways and taxiways. The second project, called Capstone, is an FAA-sponsored program based in Alaska and focusing on general aviation safety. Alaska has a specific safety problem because of several factors: it lacks radar coverage in most areas of the state; the terrain is severe; the weather can be fast-changing and extreme; and there are a large number of general aviation pilots in proportion to the lower 48 states. In fact the accident rate in Alaska is at least four times higher than in the lower 48. Although Alaska's commuter airplanes make up only 10-15 percent of the U.S. commuter aircraft inventory, they account for more than a third of commuter aircraft accidents nationwide. As of January 1, 2001, ADS-B was deployed in Bethel, Alaska to provide air traffic services, including air traffic surveillance. Bethel is one of the busiest non-radar remote air traffic areas, but until January, it was without the radar-like services ADS-B provides.
ADS-B is becoming a critical component of free-flight air traffic management systems worldwide, as is GPS technology for aviation. Already, Eurocontrol, the European Air Traffic Control agency, is evaluating ADS-B use in Europe, and a version of ADS-B is currently being demonstrated in aircraft operating in Northern Europe.
Why is it important?
"The implications of using ADS-B for air traffic surveillance are extremely important for worldwide aviation safety since much of the world is without radar coverage," comments Narkus-Kramer. "This technology has the potential of filling in huge gaps in radar coverage including vast areas in South America and Africa, as well as remote areas of the United States."
"But," Narkus-Kramer cautioned, "because ADS-B represents a major change in how information is provided to controllers and pilots, its full implementation will take time. We all want to make sure that the system is tested and re-tested and that backup systems are in place, so that any glitches are removed before the system is fully in place."
However, this doesn't mean that no progress will be made over the next five years. The use of ADS-B for radar-like services in areas that do not have radar is likely to occur in several other locations over the next three to five years. It is also anticipated that this technology will be introduced into aircraft and on controller displays to help prevent runway incursions.
ADS-B and GPS technology standards and regulations are available through Global. See the product section of this newsletter for a partial listing.