RNAV instrument approaches with LPV lines of minimadown to 200 ft (LPV-200) above the runway thresholdallow airport access equivalent to a category I instrumentlanding system. Recently there has been much interest inthe feasibility of providing a robust LPV-200 serviceworldwide through the 2020s relying on a form ofReceiver Autonomous Integrity Monitoring (RAIM)called Advanced RAIM (ARAIM). ARAIM for LPV-200 instrument approaches must consider the possibleoccurrence of a constellation-wide fault affecting allsatellites in a constellation in a mutually consistentmanner such that the fault is completely undetectable byRAIM, unless another independent constellationunaffected by the fault is used in the position solution. Apossible constellation-wide, consistent fault could occurin the generation of Earth Orientation Parameters (EOPs)and EOP Predictions (EOPPs). These faults are ofparticular concern as they have been identified as apotential integrity-failure mode in the current GPSStandard Positioning Service (SPS) PerformanceStandard. EOPs are used to transform between groundbasedcoordinates (terrestrial reference frame) and“inertial” coordinates (celestial reference frame). Severaldifferent ARAIM methods have been published proposingways to handle constellation-wide satellite faults such asan EOP fault, assuming that the EOP fault affects thewhole constellation (or one of the two constellations iftwo constellations are used). Because ephemeris data isnormally uploaded to all satellites in the constellationtypically one satellite at a time in the current GPS system,this paper evaluates how an ordinary ARAIM algorithmwould perform in the presence of the EOP fault when theephemeris data is uploaded to the satellites one at a timeThe analysis develops criteria to determine under whatconditions in terms of satellite update intervals, maximumdelays before the fault is detected/removed by the GPSsystem, and number of satellites in view, EOP faults canbe detected by ARAIM before navigation integrity iscompromised. The criteria, in turn, are used to evaluatethe availability of integrity in the presence of EOP fault.The results show that the overall average availability forboth horizontal and vertical integrity performance is 100percent if the number of satellites in view is 9 or larger forGPS; however, the overall average availability (overdifferent numbers of satellites in view) is below 99percent for most cases except when the satellite updatetime interval is relatively large with the 24-satellite GPSconstellation for horizontal integrity.
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