When is it necessary to notify ATC when in radar contact?

Notifying Air Traffic Control (ATC) is crucial for maintaining safety and efficient traffic management, especially while in radar contact. One specific situation that requires communication with ATC is when an aircraft is leaving an assigned holding fix or point. This ensures that ATC is aware of your aircraft's position and can manage any traffic accordingly.

When you leave a holding fix, ATC needs to know your intentions and updated position to avoid potential conflicts with other aircraft. This communication helps facilitate a smooth transition from the holding pattern to a new phase of flight, whether it involves proceeding on-course, starting an approach, or entering a new segment of your flight plan.

While other scenarios, like deviating from a flight plan or entering a new sector, may also require communication with ATC, the specific requirement highlighted here is the need to notify them when departing a holding fix. This is a standard procedure to ensure safety and effective airspace management.