Which abbreviation should pilots use to indicate they are passing a waypoint?

When pilots want to indicate that they are passing a waypoint, they should use the abbreviation "RP," which stands for "Report Point." This communication is essential in air traffic control as it helps controllers track aircraft positions and manage traffic effectively. By signaling that they are passing a waypoint, pilots provide ATC with critical information about their location along their route, enabling better coordination and safety in the airspace.

The other abbreviations do not correspond to the standard terminology used for reporting waypoints. Each has a different meaning; therefore, they are not suitable for this specific context within air traffic communications. This highlights the importance of using correct abbreviations to ensure clear and efficient communication between pilots and air traffic controllers.