RAIM for WAAS Category I Precision Approach

John H. Kraemer, Gerald Y. Chin, Giau C. Nim, Karen L. Van Dyke

Abstract:	This paper deals with the use of Receiver Autonomous Integrity Monitoring (RAIM) to supplement the FAA’s Wide Area Augmentation System (WAAS). Integrity refers to the capability of a navigation or landing system to provide a timely warning when the system no longer meets specifications and should not be used. WAAS will provide the integrity for Category I precision approach and RAIM will serve in a back-up role. RAIM can protect against local error sources (tropospheric, ionospheric, and multipath effects) not observable to the WAAS ground stations. RAIM will not, however, be required for an approach to be made. If RAIM is available and indicates that there is an integrity problem, the approach will not be made. The following issues are treated in this paper: a) development of an error model for RAIM backup to WAAS, b) RAIM availability as a function of missed alert rate for various combinations of WAAS GEOs and GPS and GPS/GLONASS satellites, c) the impact on availability of up to three satellite failures, and d) RAIM performance improvement from a 2 nd coded civil frequency.
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:	1375 - 1384
Cite this article:	Kraemer, John H., Chin, Gerald Y., Nim, Giau C., Van Dyke, Karen L., "RAIM for WAAS Category I Precision Approach," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1375-1384.
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