What is the recommended separation for an aircraft from the edge of the radar scope/display when it is 40 miles or more away from the radar antenna?

The recommended separation of 5 miles from the edge of the radar scope/display for an aircraft that is 40 miles or more away from the radar antenna is based on ensuring optimal radar coverage and accuracy. At greater distances, radar beam spread and potential inaccuracies in positioning increase, which can lead to challenges in tracking aircraft effectively.

By maintaining a 5-mile separation, air traffic controllers can ensure that any potential tracking errors or inaccuracies that may occur due to radar limitations are kept within safe margins. This clearance helps in preventing false readings and ensuring that aircraft are properly distinguished from one another, enhancing safety in airspace management. The choice reflects adherence to established best practices within aviation safety protocols, emphasizing the importance of sufficient buffer zones in radar operations.