What determines station passage in TACAN?

The correct determination of station passage in TACAN (Tactical Air Navigation) can be identified when the range indicator stops decreasing. This is due to the nature of how TACAN operates; it provides both distance measuring equipment (DME) functionality and azimuth information.

When an aircraft is approaching the TACAN station, the distance (or range) to the station is continuously decreasing. As the aircraft reaches the exact point over the station, the distance no longer decreases and starts to increase. Therefore, the moment the range indicator ceases to show a decreasing distance signifies that the aircraft has effectively passed over the station.

This information is critical for pilots navigating using TACAN as it assists them in understanding their position relative to the station and helps ensure accurate navigation during approaches and departures. This way, the correct identification of station passage allows for appropriate navigation strategies as the aircraft continues its journey.