What indicates station passage at a TACAN?

When determining station passage at a TACAN (Tactical Air Navigation) system, the correct indication is when the range stops decreasing. This means that when an aircraft is approaching the TACAN station, the range information begins to reflect a decreasing distance until the aircraft reaches the station. At this point, the range value will stabilize and eventually start to increase as the aircraft moves away from the TACAN station.

Monitoring the range is crucial for pilots using TACAN for navigation, and recognizing when the range transitions from decreasing to stable or increasing is pivotal for accurate navigation and understanding one’s position relative to the station. This transition point is what signals that the aircraft has effectively passed the station, confirming the successful navigation around the point.

The other options relate to different aspects of TACAN operations but do not convey the specific indication of station passage.