Operators with ADS-B Out systems that use selective availability (SA-Aware) receivers are no longer required to perform a preflight performance availability prediction check on the FAA’s service availability prediction tool website before operating on routes in ADS-B-required airspace. The FAA’s new policy statement said that, based on seven years of data, GPS receivers with SA-Aware “consistently provide an equivalent availability to that of radar at 99.9 percent or greater operational availability.”
Furthermore, “operators of aircraft equipped with SA-Aware GPS receivers during periods of GPS constellation degradation that negatively impact the ability of ADS-B to meet performance requirements…will be deemed compliant with the ADS-B Out rule requirements.” For aircraft equipped with GPS receivers that do not meet SA-Aware minimum performance requirements, operators must continue to run preflight prediction analysis.
The agency also discussed situations that might warrant a follow-up preflight availability prediction. For example, a change in the satellite constellation. If an operator becomes aware of any change that could result in degraded GPS performance before receiving an initial ATC clearance, the operator should conduct a subsequent preflight availability prediction, the agency said.