What is the required separation distance below FL180 and within 40 miles of the antenna?

The required separation distance below FL180 and within 40 miles of the antenna is 3 miles if specified in a facility directive. This distance is established to ensure safe operational practices and effective management of air traffic in areas affected by radar service, particularly within the vicinity of the antenna. The specific mention of a facility directive clarifies that operational procedures can vary based on local regulations or circumstances, making it essential for controllers to adhere to the guidance provided in these directives.

Understanding that separation requirements can vary based on altitude, distance, and operational context is critical for ensuring safety in airspace management. This reflects the dynamic nature of air traffic situations and the importance of clear and defined operational protocols that are tailored to specific contexts.