Flight Operations Manual Practice Test

When final approach lateral guidance is provided by a ground-based NAVAID or LOC, the information that guides you is the actual signal data from that facility. You must monitor the NAVAID/LOC raw data—the true signal information the nav receiver uses to derive the course and any indicators of signal validity or quality. Watching this data ensures the FMS is following a real, current course and that the localizer or VOR signal is alive and usable. If the raw data shows trouble—signal loss, degradation, or an invalid course—the lateral guidance can no longer be trusted, and you should intervene. GPS position is helpful for situational awareness, but it does not verify the integrity of the ground-based approach signal; flight plan name is not related to the approach guidance, and autopilot status, while important for automation, does not confirm the accuracy of the NAVAID-based course.