Operational Aspects of GPS for Precision Approach and Landing

Manfred Dieroff, Xiaogang Gu, Bernd Tiemeyer, and Stefan Vieweg

Abstract:	When the worldwide first automatic landing using differential GPS was officially demonstrated in July 1989 in Braunschweig, it could be proven that satellite navigation can be used even under bad weather conditions of ICAO CAT III. Meanwhile there is no longer any doubt that, from the point of positioning accuracy, GPS can be used for precision approaches and landings. At present, the Institute of Flight Guidance and Control of the University of Braunschweig is investigating the operational aspects of using DGPS for precision approaches of general aviation aircraft under a contract with the German Ministry of Research and Technology. Results of these operational investigations will be presented in this paper. They are subdivided into three groups: simulation, ground test and flight test. The simulation is used to answer the question of how to integrate GPS and inertial sensors as well as additional sensors such as altimeters if they are necessary. The integration concept will be demonstrated. Simulation is also used to investigate the problem of the integrity of this integrated system with respect to GPS failures. It is of main interest for any certification authority to know how the positioning accuracy decreases when the GPS ground station or the airborne receiver fails or the signal quality is degraded by Selective Availability (S/A). Partial failures due to satellite masking and total failures are distinguished. These results include investigations on the influence of dynamic maneuvers on the systemaccuracy, sensor error behaviour and typical influences such as receiver update rate or DOP changes. The occuring errors are put into relation to the I ments. GPS can only be used and landing guidance rated in a different :A0 requirefor approach if it is opeal mode. As the positioning accuracy depends on a number of parameters, ground and flight tests were performed to investigate the influence of latitude, time of day, propagation errors, and, -especially-,length of baselines between the two receivers. Finally, results of combining different receivers and flight tests with laser tracker reference will be presented.
Published in:	Proceedings of the 48th Annual Meeting of The Institute of Navigation (1992) June 29 - 1, 1992 ANA Westin Hotel Dayton, OH
Pages:	373 - 382
Cite this article:	Dieroff, Manfred, Gu, Xiaogang, Tiemeyer, Bernd, Vieweg, Stefan, "Operational Aspects of GPS for Precision Approach and Landing," Proceedings of the 48th Annual Meeting of The Institute of Navigation (1992), Dayton, OH, June 1992, pp. 373-382.
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