What is the correct separation of an aircraft from the edge of airspace when radar separation is NOT being used and the aircraft is 40 miles or more from the radar antenna?

When radar separation is not being utilized and the aircraft is at a distance of 40 miles or more from the radar antenna, the appropriate separation from the edge of airspace is effectively 5 miles. This requirement is established to ensure adequate spacing between aircraft and reduces the risk of airspace incursions, particularly when radar capabilities are not in place to monitor their positions closely. This clearance distance allows for safer operations and aids in maintaining a buffer between aircraft as they navigate away from controlled airspace or into adjacent sectors.

The other distances provided, such as 3 miles, 2.5 miles, and 1.5 miles, do not meet the established safety standards for such a distance from the edge of airspace without radar oversight, which emphasizes the need for greater separation in those circumstances.