A GBAS Landing System Model for CAT I

Young Nam, Tom Zalesak, Barbara Clark, Tim Murphy, Len Anderson and Bruce DeCleene

Abstract:	This paper presents the development of a model of the errors associated with the output of an airborne GNSS Ground Based Augmentation System (GBAS) receiver. The development of such a model is a necessary step in the development and validation of satellite based landing systems. Standards groups such as the International Civil Aviation Organization (ICAO), RTCA and the European Organization for Civil Aviation Equipment (EUROCAE) are maturing and harmonizing standards for ground based augmentation (GBAS) of the Global Navigation Satellite System (GNSS) for aviation use including precision approach operations. Within the US National Air Space (NAS), the GPS/LAAS system (Global Positioning System augmented with a local area augmentation system) will provide this service. RTCA, functioning as a Federal Advisory Committee, has developed a concept of Performance Type to classify requirements for the combined performance of the signal-in-space and fault free airborne GPS/LAAS. The concept currently defines three levels of performance. Requirements for Performance Types 1, 2, and 3 were derived from Instrument Landing System (ILS) requirements and are intended to support Category I, II and IIIa, and IIIb operations, respectively. The development of the infrastructure within the aviation community to widely field systems compliant with the standards is well underway. Certification and approvals for use of GNSS/GBAS equipment on aircraft is one area being addressed. Historically, models of navigation system errors (NSE) based on the requirements for the NAVAID have been used in the aircraft certification process in the context of Monte Carlo simulation trials. In addition to NSE, the simulations exercise the range of conditions an aircraft may see during service, including the variation of atmospheric effects (wind speed and direction, turbulence level, etc.) and aircraft configuration (weight, center of gravity location, flap settings, etc.). Samples of aircraft landing performance for Monte Carlo trials are included.
Published in:	Proceedings of the IAIN World Congress and the 56th Annual Meeting of The Institute of Navigation (2000) June 26 - 28, 2000 The Catamaran Resort Hotel San Diego, CA
Pages:	679 - 688
Cite this article:	Nam, Young, Zalesak, Tom, Clark, Barbara, Murphy, Tim, Anderson, Len, DeCleene, Bruce, "A GBAS Landing System Model for CAT I," Proceedings of the IAIN World Congress and the 56th Annual Meeting of The Institute of Navigation (2000), San Diego, CA, June 2000, pp. 679-688.
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