DGPS Category IIIB Feasibility Demonstration - Landing System With Flight Test Results

Dave Kaufmann, Glyn Rornrell, Ron Brown, and Greg Johnson

Abstract:	E-Systems Montek Division successfully completed a series of 100 precision approach and landings at NASA Ames Research Center in June 1995 under contract to the FEDSIM Software Management Center’s FAA client. The E-Systems Automatic Landing System (ALS) accomplished its objective in demonstrating that DGPS, augmented with Kinematic Carrier Phase Tracking (KCPT) technology, can meet Cat IIIb autoland requirements for navigation sensor error (NSE) and integrity. E-Systems Montek Division was assisted in this effort by E-Systems ECI, Falls Church and Greenville Divisions and by Ashtech, ARINC, Litton Aero Products and Barken International. The system demonstrated two significant strengths: 1) The KCPT fast ambiguity resolution using two frequencies demonstrated carrier phase ambiguity resolution and tracking accuracies consistently, with high integrity, from the final approach fix at 5.25 nm through touchdown and roll-out. 2) The avionics RAlM technique based on carrier phase tracking demonstrated sufficient accuracy margin to reliably provide low probabilities of missed detection and false alarm during the testing that included static integrity tests. The equipment includes a reference station, integrity monitor and avionics. Fast carrier phase ambiguity resolution using two frequencies was demonstrated. Ground integrity monitoring and aircraft RAIM was utilized to provide probability of missed detection of 1 x lo-‘. ILS look- alike guidance was computed and provided to a Westwind 1124 aircraft. NASA supplied and operated its laser tracker for the independent truth system. Analysis of 100 approaches and 10 static integrity tests shows navigation sensor 95% accuracies of 0.3 1 meter vertical and 1.6 meters lateral achieved at 50 ft height above threshold (HAT), compared to the requirement of 1.2 meters and 4 meters, respectively. The significant results demonstrate the capability of GPS to meet existing sensor error requirements for Cat III ILS from the final approach point, thus minimzing the cost of recertifying current dual ILS autoland capable aircraft for GPS CatII/III precision approach. The sensor accuracy performance includes errors in the laser tracker and the aircraft reflector offset lever arm.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	127 - 136
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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