Plain English Meaning

Official notices that tell pilots when GPS satellites will be out of service or working poorly, so they know whether they can rely on GPS for the flight they are planning.

Full Definition

Notices to Air Missions that report the operational status of the GPS satellite constellation, including scheduled satellite outages, unscheduled outages, and degraded service that may affect the availability or integrity of GPS-based navigation. Pilots planning IFR flight using GPS are required to check these notices before departure to confirm that the satellites needed for the route and approach will be usable.