A340 - DGPS Landing Experiment

Julie de Cevins and Pascal Ponsot

Abstract:	Since October 95, Airbus Industrie has been performing Differential GPS approaches and landings on A340 test aircraft on Toulouse and other airports. The main goal was to prove DGPS Cat 1 accuracy feasibility on a big airplane such as A340 and, if possible, Cat 2. The DGPS airborne equipment is linked to the auto-pilot and to the displays, in order to provide “IIS-like” information to the auto-pilot and to the crew. The objectives of this experiment are of different types : . test the chosen airborne architecture, and especially the flight management system interface and the auto-pilot interface with DGPS. . test different vendor equipment (Litton and Sextant) and evaluate accuracy, . test interoperability between the different ground and airborne equipment, . evaluate the environmental contribution on airborne and ground stations. 180 approaches have been performed with Sextant and Litton, using a SCAT1 Wilcox/Thomson ground sation equipment. They show very good results, and at least Cat 1 and Cat 2 accuracy. First approach was good enough to be autoland and rollout. These approaches have been performed on different airports in France (Montpellier and Toulouse), in China (Beijing, Shanghai and Canton), in South Africa (Mmabatho) and in Mauritius (Plaisance) . Results show that there is : . better than 2 meters lateral and 3 meters vertical accuracy, . simplicity and ease of installation of the ground station . importance of the ground station antenna location to avoid multipath and masking of the satellites, . importance of ground station integrity and availability. . excellent results to “envisage” Cat 3 autoland with improvement of Ground Station Integrity, Availability and Monitoring. This experiment is part of a more global project which is to certify DGPS initially for Category 1 landing minima by mid 1997. Next steps of this program will be to confirm the aircraft architecture, to check the availability and the integrity of the system by simulation, to study and define the Human Machine Interface, and last but not least to go through the certification process itself. This phase will be the most critical one, as the standards are still being written and as the ground station and airborne receiver will probably in a first approach have to be certified all together.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	763 - 772
Cite this article:	de Cevins, Julie, Ponsot, Pascal, "A340 - DGPS Landing Experiment," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 763-772.
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