Standards for ARAIM ISM Data Analysis

Advanced Receiver Autonomous Integrity Monitoring (ARAIM) relies on accurate and safe information to be provided to the aircraft through an Integrity Support Message (ISM). The ISM safety parameters are based on service commitments established by each core GNSS constellation. Each core constellation is expected to broadcast its own set of parameters that apply to its own satellites. Users can monitor more than one constellation, obtaining the required ISM parameters for each one. While the state associated with each core constellation is responsible for determining and meeting their own chosen set of parameters, it is important that these parameters are independently monitored and evaluated for performance. For example, even though the U.S. will be responsible for determining and broadcasting ISM parameters that apply to GPS, many other countries will be interested in allowing aircraft to use GPS as part of ARAIM to support aircraft navigation over their own airspace. Thus, it is important that these countries be able to evaluate whether or not the GPS ISM parameters are consistent with observed data. This paper provides proposed standards for data collection and evaluation that allows all interested parties to agree on whether or not the provided parameters are safe to use.