What is indicated by a waypoint with a circle around it on a STAR?

A waypoint with a circle around it on a Standard Terminal Arrival Route (STAR) indicates a fly-over point. This is a specific type of waypoint that requires an aircraft to actually fly over it to ensure proper navigation and route adherence. The circular notation is used to differentiate it from waypoints that might serve as reference points for altitude changes or other navigational purposes.

In the context of air traffic procedures, a fly-over point is crucial for maintaining the intended flight path, especially during approaches to busy airports. Pilots must be aware of such waypoints to execute their approaches accurately and safely, ensuring they do not deviate from the established route.

Mandatory altitude requirements, holding patterns, and descent requirements, while important in their own right, represent different aspects of flight procedures and are not indicated by the circular symbol associated with fly-over waypoints. Each of these other indicators would have distinct symbols or designations that communicate their specific functions within an air traffic control environment.