Validating DGPS Airspace Positioning Using Airport Surveillance Radar (ASR) Data

John R. Foggia

Abstract:	Emerging Differential GPS (DGPS) ground and airborne equipment permits satellite-based GFS precision approaches, positioning GPS as the next generation navigation and landing aid. The capability of GPS-aided terminal area guidance, in terms of straight, curved, or segmented precision guidance (i.e., horizontal and vertical) implies new strategies for launching and recovering aircraft - not only precision approach guidance, but the same precision for dqxutures, missed approach, standard arrivals, etc. Weather no longer is the [only] critical factor in determining the types of navigational aids an airport subscribes to. Operational flexibdity involving today’s visual procedures conducted under Instrument Meteorological Conditions (IMC) will lead to VFR acceptance rates under IFR, representing potentials for significant delay reductiotdcapacity enhancement using existing aiqvort infrastrudm. For the first time, land use compatibility considerations and noise abatement operational needs, can influence the decision to move toward a new navigational system. We are at the very leading edge of a revolution in airspace managemen~ and airports as well as air camiers have an opportunity to function as equal planning partners with F&L regarding how the operational fiture will be developed. With Controlled Flight into Terrain (CFIT) cited by NTSB as the most critical safety factor facing aviation today, DGPS precision capabilities will directly address the statistic that 78% of CFIT accidents since 1970 occurred under non-precision approach conditions. In addition to the final approach segmen~ DGPS aided FMS/RNAV and Required Navigation Performance (RNP) procedunss will allow ILS4ike flight path adherence (precision) along terminal area flight segments other than the FAS. To get there from here, FAA, operators, airports and communities need a body of objective data to demonstrate the assertion that D(3PS inputs to navigation actually achieve the results promoted. This data must be collected under non-demonstration conditions, i.e., data collected at a variety of airports, from a variety of aircraft randomly flying DGPS approaches./Area Navigation (RNAV) routes, under the non-controlled conditions of revenue service. Industry conditions are emerging that will result in airports with certified DGPS ground stations, and air carrier jets equipped to fly against the augmented data. Many airports are also equipped with capability to collect Airport Radar Surveillance (ASR) data on a regular basis (Chicago O’HareiMidway, Newark/La Guardia/Kennedy, Phoenix, Seattle, Denver, San Francisco, Minneapolis, Boston, and others). These facilities can routinely collect a non-contiguous temporahpatial data set of participating DGPS-based aircraft approaches. This dataset - non-contiguous in time and space - satisfies a number of statistical requirements that establishes a valid proof of concept for airspace redesign actions. A phased approach collecting FMS/RNAV and RNP (raw GPS-aided) procedures, and later DGPS-aided procedures, coupled with the vast archive of ASR data documenting existing condhions, provides definitive performance documentation.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	449 - 459
Cite this article:	Foggia, John R., "Validating DGPS Airspace Positioning Using Airport Surveillance Radar (ASR) Data," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 449-459.
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