Investigation of the Potential Application of the Global Positioning System (GPS) for Precision Approaches

Lawrence Hogle

Abstract:	The Instrument Landing System (ILS) currently serves as the international standard for precision approach landing operations. The Microwave Landing System (MLS) is being implemented to replace ILS as the international standard. These systems provide precision approach guidance (i.e., vertical as well as lateral guidance). The satellite-based Global Positioning System (GPS) is a high accuracy navigation system with a potential to become a sole means air navigation system for the United States. Application of GPS for civil aircraft operations is targeted for the enroute and nonprecision approach phases of flight. This paper investigates the potential of using GPS for precision approach landing operations. The principal issue addressed is accuracy. The results of the investigation show that GPS does not presently satisfy the precision approach requirements as specified by the International Civil Aviation Organization (ICAO). Although the horizontal accuracy of GPS is within the requirement specified for a precision approach to 200 feet altitude above the runway, it is shown that GPS, even when operating in a differential mode, does not achieve the required vertical accuracy. The achievable integrity and coverage reliability are also shown to require further improvement for GPS to be considered for use as a precision approach system.
Published in:	Proceedings of the 1988 National Technical Meeting of The Institute of Navigation January 26 - 29, 1988 Santa Barbara, CA
Pages:	279 - 286
Cite this article:	Hogle, Lawrence, "Investigation of the Potential Application of the Global Positioning System (GPS) for Precision Approaches," Proceedings of the 1988 National Technical Meeting of The Institute of Navigation, Santa Barbara, CA, January 1988, pp. 279-286.
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