What should a pilot do if RAIM is lost after reaching the FAF?

When a pilot loses RAIM (Receiver Autonomous Integrity Monitoring) after reaching the Final Approach Fix (FAF), the most appropriate action is to go missed approach. RAIM is essential for ensuring the integrity and accuracy of the GPS signals used for navigation. If RAIM is lost, it means that the pilot cannot verify the reliability of the GPS information, which is critical for safely conducting the precision approach.

Choosing to execute a missed approach ensures that the pilot prioritizes safety by transitioning to a standard procedure designed for situations where navigating with unreliable systems could compromise the safety of the flight. It prevents the pilot from continuing to land based on potentially erroneous data, which could lead to dangerous situations, especially when precision is required close to the runway.

While other options might seem feasible, they do not address the fundamental issue of navigation reliability. Continuing to land as planned without reliable navigation data increases the risk of an accident. Switching to autopilot does not resolve the lack of RAIM, as the autopilot is still reliant on the same unreliable GPS signals for navigation. Landing visually only may not be an option if conditions do not allow for a safe visual approach. Therefore, going missed approach is the safest and most prudent choice.