In relation to VOR and TACAN, how is station passage characterized?

Station passage in relation to VOR (VHF Omnidirectional Range) and TACAN (Tactical Air Navigation) is characterized by the moment the TO-FROM indicator changes from TO to FROM. This change signifies that the aircraft has crossed over the station, marking the exact point of station passage.

Understanding the operation of the TO-FROM indicator is crucial for pilots, as it provides direct information about the aircraft's relative position to the navigational aid. When the indicator shifts to FROM, it confirms that the aircraft has passed the VOR or TACAN station and is now moving away from it. This moment is critical for timing and navigation, especially when planning maneuvers such as waypoints or approaches to airfields.

The other options provide misconceptions about how station passage is defined and measured. For instance, it is not based on distance from the NAVAID, altitude, or the angle of approach, but rather, it is distinctly marked by the indication on the navigation display. Thus, recognizing the TO-FROM indicator's shift is essential for properly identifying station passage.