When does a VOR station passage occur?

A VOR station passage occurs when the TO flag changes to a FROM flag. This indicates that the aircraft has crossed the VOR station's radial, and the navigation system is now receiving signals from the station indicating that the aircraft is moving away from it.

In practical navigation terms, pilots use the VOR to determine their position relative to the station. When the TO flag is displayed, it tells the pilot that the aircraft is approaching the station; once the aircraft crosses the station, the flag switches to FROM, providing the pilot with vital information about their current navigational status. This change is a clear and unambiguous sign that the aircraft is exactly at the VOR station’s location, marking the moment of passage.

Understanding this concept is crucial for accurate navigation, especially in situations that require precise position reporting or when intercepting specific airways or routes.