Experimental Flight Tests with EGNOS on A380 to Support RNAV LPV Operations

L. Azoulai, S. Virag, R. Leinekugel-Le-Cocq, C. Germa, B. Charlot, P. Durel

Abstract:	Several Satellite Based Augmentation Systems are being used by the Aviation community or under development around the world. WAAS covers the US Air Space, whereas EGNOS covers European Civil Aviation Conference Airspace, MSAS the Japanese Airspace and GAGAN the Indian Airspace. While WAAS offers the capability to perform RNAV operations with LPV 200 ft minima in US National Airspace, EGNOS should be able to offer, in the near term, the same capability in Europe. Airbus will equip its A350 XWB with SBAS in order to offer to its customers the capability to fly published RNAV GPS approaches with LPV 200 minima, without navigation ground infrastructure at Airport Vicinity and providing a geometric vertical guidance, free of temperature and barometric setting errors. In the course of pre-development activities, Airbus has performed experimental flight tests with an A380, using on one side, one MMR prototype, providing LOC and Glide deviations based on SBAS, and using, on the other side, the certified version of the A380 MMR using GBAS. Indeed, Airbus developed a quick win architecture solution to perform these trials by modifying only the MMR system without any other modification on-board the aircraft. As a consequence, Human Machine Interface used was the GLS certified one, which in turn, gave the possibility to the crew to compare GBAS and SBAS behaviours. In addition, the aircraft had flown the already published experimental approach procedure used during GBAS certification, without the need to publish a specific RNAV LPV experimental procedure. The aims of these experimental flight tests were numerous among which data accumulation on EGNOS, compare GBAS and SBAS behaviours and performance, thanks to a DGPS based trajectography, during aircraft manoeuvers, showing the ILS look alike concept applicability to SBAS. Results will feed airborne requirement maturity and potentially, feedback to the whole aviation community for the development of RNAV GNSS with LPV minima and SBAS standards improvement for the benefit of interoperability. On the ground side, EGNOS data, as well as measurements of local reference stations, are recorded and analysed. This allows to precisely evaluate the system performance and behavior in synchronization with the flight trials. Comparison with data, recorded by airborne receiver, enable to explain any observation that could be made on board the aircraft. The goal of this paper is to present Airbus vision with regard to the use of GNSS to perform published RNAV GNSS approaches with LPV 200 ft minima, first by using SBAS; present the trials organization and actors, and particularly describe the innovative architecture solution developed to perform these trials. Analysis and comparison of ground and airborne data have been performed. Observations made on the SBAS signal (EGNOS and WAAS) from the ground perspective and at the output of the MMR are analyzed and explained from the performance perspective but also from the operational perspective. Finally, this paper provides indications on the SBAS quality to perform such approaches on an Air Transport aircraft and will provide recommendations for future GNSS systems in order to meet the same level of performance worldwide.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	1203 - 1215
Cite this article:	Azoulai, L., Virag, S., Leinekugel-Le-Cocq, R., Germa, C., Charlot, B., Durel, P., "Experimental Flight Tests with EGNOS on A380 to Support RNAV LPV Operations," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 1203-1215.
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