ARAIM Operational Performance Tested in Flight

Abstract

This paper presents a flight performance analysis of next generation ARAIM based on GPS and GLONASS dual-frequency data collected during flight trials using DLR’s research aircraft ATTAS. The test results are based on joint PVT and ARAIM post-processing and investigate potential differences between simulated ARAIM performance levels and actual operational performance. The PVT and ARAIM performance is evaluated with respect to positioning accuracy, position error bounding (integrity) and availability of LPV200 (Localizer Performance with Vertical Guidance) service during typical arrival and approach maneuvers. This evaluation takes into account operational constraints such as signal outages due to banking. These constraints are not included in analyzes based on static user grids with fixed elevation masks and thus constitute the characteristic feature of this study. To ensure that the performance metrics obtained can be compared with performance simulation results, the error model targeted at future GNSS with L1 and L5 signals is adapted to represent the error model for the data collected, L1 and L2. Compliance with integrity requirements is demonstrated conditioned on a fault-free scenario, which is ensured by post-processing and analyzing the airborne data together with ground reference data. Flight test results are compared with results from a predictive study that estimates ARAIM performance with a simulation for a static user in the vicinity of the airport. The comparability of these results is made possible by adjusting the dual frequency user range error model to the scenario at hand and applying the same SIS error parameters both to the real-data ARAIM processing chain and the simulated scenario.