What does the range indicator on a TACAN do when passing directly over the station?

When passing directly over a TACAN (Tactical Air Navigation) station, the range indicator will indicate zero. This is because TACAN measures the distance between the aircraft and the station based on time delays of signals transmitted back and forth. As the aircraft approaches the station, the range decreases continually until it is directly over the station, at which point the distance (or range) is effectively zero.

The correct understanding of the function of the TACAN range indicator is crucial for navigation, as pilots need to interpret this information to ascertain their position relative to the ground station. The state of the range indicator at this point serves as a clear indicator of the aircraft's proximity to the TACAN station, allowing pilots to make informed decisions about their navigation and flight path.