What happens if not enough satellites are available for RAIM?

When not enough satellites are available for Receiver Autonomous Integrity Monitoring (RAIM), the primary function of RAIM is to ensure the integrity of the GPS signal being used for navigation. If the system detects that there are not enough satellites to provide a reliable position fix, it will alert the user of unreliable information. This alert is crucial because it informs the pilot that the positional data cannot be trusted, which is critical for safe navigation, especially in instrument flight operations where precise positioning is required.

RAIM is designed to work with a minimum of five satellites to confirm the integrity of the data, as it uses redundancy to check for anomalies. If fewer than the necessary number of satellites are available, the system will not assume that the remaining data is accurate and will provide a warning to the user. This allows pilots to make informed decisions about their navigation rather than risking reliance on potentially erroneous GPS information.