What distance is represented by full deflection on GPS for approach mode?

In GPS approach mode, full deflection of the needle indicates a lateral deviation from the course. The correct distance represented by full deflection on a GPS device for approach mode is 0.3 nautical miles. This means that when the deviation indicator on the GPS shows full deflection, the aircraft is approximately 0.3 nautical miles away from the intended course centerline.

This standard is configured to provide pilots with precise situational awareness during the critical phases of descent and approach. A full deflection warning lets the pilot know that adjustments are needed to correct the course, ensuring they remain on track to safely reach the runway.

The distances represented by other options are not used for the approach mode in this context, as they exceed the typical margin for error that is effective for landing and may lead to less immediate corrective action being taken by the pilot. The 0.3 nautical mile increment allows for timely reaction, especially in circumstances where precise navigation is essential for safe operations.