When planning an IFR cross-country flight using GPS, what is a critical step to consider regarding GPS signals?

When planning an IFR cross-country flight using GPS, confirming NOTAMs (Notices to Airmen) for unreliable signals is vital because GPS functionality can be affected by numerous factors, including maintenance work, system outages, or atmospheric conditions that cause signal degradation. NOTAMs provide up-to-date information regarding any advisories or alerts pertaining to GPS signal reliability in certain airspace or regions. Understanding the status of GPS signals helps pilots to make informed decisions about their navigation options and not solely rely on GPS, especially when alternatives, such as VORs or NDBs, might be necessary in case of GPS failure during the flight.

In this context, monitoring fuel availability or consulting other pilots may be important considerations, but they do not directly address the integrity of the GPS signals used for navigation. Similarly, while monitoring radio frequencies is essential for maintaining communication and receiving updates during flight, it does not specifically pertain to ensuring the reliability of GPS signals, which is crucial for adherence to IFR protocols.