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| JPALS Provides Portable Precision for Pilots October 2008
Military pilots often find themselves flying in and out of unfamiliar and even make-shift airports. Murky weather can make the task of navigating landings and take-offs even more difficult. Wartime tactics often require that pilots employ unconventional approach and departure paths. While existing navigation technology has made flying under such arduous circumstances possible, greater accuracy in instrument guidance would make pilots' jobs much safer. In order to provide pilots with navigational data detailed enough to ensure safety in bad weather and hostile conditions, MITRE is working with the Department of Defense to develop the Joint Precision Approach and Landing System (JPALS). Ted Ede, a systems engineer for the JPALS project, sums up the many reasons why MITRE wants to improve the accuracy and stability of flight data. "The technology used for the instrument landing system [ILS] employed at airports is about 60 years old. It's basically two beams that the aircraft uses to get horizontal and vertical guidance in poor visibility conditions. The system is limited, has complex siting requirements, is affected by uneven terrain in front of the runway, serves only one runway in one direction, and requires close to each runway an antenna tower that is from 30 to 50 feet tall." JPALS augments the aircraft's GPS readings, providing the pilot with a much more precise position in relation to the terrain. The system consists of units installed on the ground and in the aircraft. The ground unit receives the signals from GPS satellites, factors in JPALS' precisely known location, and broadcasts the corrections. The aircraft unit receives the corrections and adjusts the onboard GPS readings accordingly. The pilot or the plane's autopilot system can then select safe and accurate arrival and departure paths to and from the airport using those readings. Precise to Within Inches "The accuracy pilots can derive from JPALS is uncanny," says Ede. "At one airport where a version of this technology is being used, pilots were complaining. A plane's descent would be so pinpoint that the nose wheel would land on the strip of guide lights that runs down the exact center of each runway, causing the wheel to rumble."
An additional benefit of JPALS over current approach and landing systems is its range. Each JPALS ground unit can supply data across a 10-to-20 mile radius. That allows the ground unit to provide approach data to all the runways at all the airports in that area. The system will also provide a variety of flight paths to each runway. For tactical reasons, pilots may have to approach their landings from a variety of routes. JPALS can not only be programmed to support many different approaches, it can even adjust to damage suffered by landing strips during hostilities. No matter which landing strip pilots approach—or from which angle or under which circumstances—JPALS enhances the ability to land safely. JPALS will be a boon to both military and civilian pilots. "The system is designed to have a military mode and a civil mode," explains Ede. "Because MITRE has a long history of partnering with both the FAA and the Department of Defense developing air traffic systems, we can ensure that government efforts are not duplicated while developing future air guidance technology." For an Instant Airstrip, Just Add JPALS The next step in JPALS development is portability. In some cases a military pilot may not have the luxury of landing at an established airport. The demands of a campaign may require him to employ a landing strip carved out of a flat field or vacant lot—a landing strip that may be abandoned after supporting only a few sorties. Such landing sites have an even greater need for accurate GPS readings to render them usable, so MITRE is participating in the development of a portable JPALS ground unit that can be deployed quickly in any terrain. Called the Man-Pack JPALS system, the unit consists of two GPS receivers, a laptop computer, and a datalink transmitter, all packed into two backpacks. Two people can set it up in a few minutes, allowing the system to instantly transform a clear strip of land into a working airport. MITRE tested a proof-of-concept Man-Pack last fall at the William J. Hughes Technical Center in Atlantic City, New Jersey. Military aircraft, simulating combat landings at a damaged airport, successfully flew precision approaches from a variety of paths, all guided by the signals from the Man-Pack JPALS system. The Man-Pack even successfully guided flights at an airport 12 miles away. Major Martin Towey, from the Air Force Flight Standards Agency, piloted one of the aircraft during the exercise. He was astonished at the flexibility the Man-Pack could provide pilots. "The system's utilization seems limited only by one's imagination," he says. When it comes to safety of our nation's pilots, MITRE puts no limits on its imagination. Thanks to our innovative research, within the next decade JPALS will be considered a pilot's best friend. —by Christopher Lockheardt Related Information Articles and News
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| Page last updated: October 13, 2008 | Top of page |
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