Investigation of a Total System Tolerance Model for Precision Approaches Using GPS/Wide Area Augmentation System

Ralph Sexton, Shahar Ladecky

Abstract:	The implementation of landing systems for precision approaches, such as ILS and MLS involved a process to mathematically describe the component parameters of the system tolerance, characterize the distribution of each, and combine these into a total system tolerance (TST) probabilistic model. Applications for such models have included establishing obstacle protection surfaces used in the design of precision instrument approach procedures and in development of the International Civil Aviation Organization (ICAO) collision risk model (CRM) to assess the risk of collision with obstacles in specific runway and obstacle environments. This paper investigates a total system tolerance model for GPS/WAAS precision approaches using a systematic approach thorough analytical studies and analyses of flight test data. First, it identifies component parameters of the GPS/WAAS errors/tolerances appropriate to precision approaches, and then characterizes each one. Second, it mathematically describes the component parameters and the effect on aircraft path. Finally, it combines them with aircraft and pilot models into a TST model. It will be demonstrated that the model is responsive to the changes in parameters determined by changes in system performance or observed test results, which the FAA has recently extensively collected. The analysis contained in this paper is being performed in support of the FAA and is part of the effort to develop criteria for instrument approach procedure design.
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:	1193 - 1201
Cite this article:	Sexton, Ralph, Ladecky, Shahar, "Investigation of a Total System Tolerance Model for Precision Approaches Using GPS/Wide Area Augmentation System," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1193-1201.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In