ARAIM in Flight Using GPS and GLONASS: Initial Results from a Real-time Implementation

Dynamic, mobile platforms offer the opportunity to analyze robustness to satellite outages due to aircraft maneuvers or other real-world situations where interruptions in continuity, in particular, can potentially be problematic. And real-time implementation serves to demonstrate the state of readiness of the algorithm to meet its intended purpose—providing high-integrity navigation for aircraft. To this end, a flight test was arranged to test ARAIM operation in flight. For this paper, the ARAIM user algorithm was implemented using GPS and GLONASS in real-time in flight at the airport in Atlantic City, NJ. Several flight profiles were flown to inject typical aircraft dynamics into the system. The real-time data was analyzed to understand the effects of aircraft dynamics on receiver on the horizontal and vertical protection levels. It is shown that the ARAIM algorithm may be sensitive to aircraft dynamics and that adequate characterization of the multipath errors and proper mitigation of cycle slips may play a significant role in achieving expected continuity and availability.