At a VOR, what indicates station passage?

Station passage at a VOR (VHF Omnidirectional Range) is indicated by a specific change in the TO/FROM indicator, which reflects the aircraft's position relative to the VOR station. When an aircraft passes directly over the VOR station, the TO/FROM indicator will change from a TO signal to a FROM signal. This transition denotes that the aircraft has crossed the VOR station and is now on a leg that is oriented away from the station.

This is significant because pilots use the TO/FROM indicator to determine whether they are navigating towards or away from a VOR. The first positive FROM indication confirms that the aircraft is no longer on a route towards the station but is instead departing from it, which is a critical aspect of navigation and route management.

Other choices do not accurately describe station passage. Signal loss would indicate that the VOR signal is no longer being received but does not provide information about the aircraft's position relative to the station. A TO/FROM indicator giving a first positive TO indication would occur before reaching the station, and centering the course deviation indicator generally suggests that the aircraft is on the desired radial to the VOR, not necessarily indicative of passage over the station.