What should pilots check before the flight concerning GPS?

Pilots should check GPS NOTAMS (Notice to Airmen) before a flight as these provide critical information regarding the availability and operational status of GPS resources. GPS NOTAMS can inform pilots about any outages, maintenance activities, or inaccuracies in GPS data that may affect navigation during the flight. This is particularly important as GPS is a key system used for route navigation, and knowing its reliability can significantly impact flight planning and safety. By checking these NOTAMS, pilots can ensure they are aware of any potential issues that could arise from GPS usage and can make informed decisions about their navigation options.