Design and Evaluation of Combined GPS/GLONASS LAAS Trials

David Walsh, David Lowe, Stefano Capaccio, Peter Daly, Gill Richards, Andy Wolfe, Gordon Ingle,Jim Lawson

Abstract:	The use of GPS in aviation is now accepted with extensive work being undertaken on the technological, precision and infrastructure requirements. Work has focused on providing a service that is able to operate continuously in all areas. GPS alone however is seen as being unable to satisfy the stringent requirements for some phases of flight. Of the many solutions proposed the Russian GLONASS system has been regularly overlooked. The research described in this paper aims to present GLONASS as a realistic and proven augmentation to GPS for aircraft positioning. During October 1996, the Civil Aviation Authority (CAA) Institute of Satellite Navigation (ISN) at the University of Leeds, in conjunction with the National Air Traffic Services Ltd. (NATS UK) and the Defence Evaluation and Research Agency (DERA), performed a series of landmark differential GPS/GLONASS flight tests using the DERA BAC1-11 flying laboratory. A real time differential system was constructed using two GPS/GLONASS receivers developed by the ISN and a C-band data link for the RTCA corrections. Integration onboard the aircraft with avionic sensors and flight management systems was achieved using the ARINC-429 protocol. Routes were designed and flown to evaluate the complete system over a variety of airborne dynamics for both en-route and approach situations. In total, over 16 hours of flying time was recorded, including 30 runway approaches over 9 flights.A thorough evaluation of the accuracy and integrity of the positioning system was performed. Emphasis was made in comparing the flight statistics to recognised Required Navigation Performance (RNP) figures. The paper describes in detail the project development and the results achieved. An analysis of the results that show that aircraft positioning with a GPS/GLONASS augmentation in a LAAS scenario can achieve accuracies that are both comparable to GPS alone solutions and can satisfy up to CAT II precision approach criteria, is presented. Results are also given for position propagation using velocities derived from GPS and GLONASS carrier phase measurements.
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	1641 - 1650
Cite this article:	Walsh, David, Lowe, David, Capaccio, Stefano, Daly, Peter, Richards, Gill, Wolfe, Andy, Ingle, Gordon, Lawson, Jim, "Design and Evaluation of Combined GPS/GLONASS LAAS Trials," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 1641-1650.
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