Abstract — The aviation industry has been relying more and more on the availability and accuracy of Global Navigation Satellite System (GNSS) position reports to perform some of its vital functions, like aircraft separation, terrain avoidance, and flow management. The increasing occurrence of GNSS interference recorded in recent years, both intentional and unintentional, has raised safety concerns among the aviation stakeholders and it has spurred a wave of research for tools that can help identify, understand, and mitigate these events and their impact on flight operations. Aireon, by exploiting the unique features of its system, has developed a global independent position estimator, RefTrack, with the purpose of providing a reliable source of information about the location of aircraft when GNSS position reports are not trustworthy. The generated position estimations can be used to fill gaps in aircraft tracks due to the loss of GNSS positions, or to identify GNSS interference hotspots by comparing the estimated tracks against the reported ones.
Keywords—GNSS Anomalies, Position Estimation, ADS-B, Jamming, Spoofing, Tracker, Kalman filter
