What is the definition of "Courses whose protected airspaces are coincident, overlap, or intersect and whose angular difference is greater than 135 degrees through 180 degrees inclusive"?

The definition describes "Opposite/Reciprocal Courses," which are characterized by having an angular difference that exceeds 135 degrees up to 180 degrees. In aviation, this means that two flight paths are moving in nearly opposite directions, effectively being 180 degrees apart at their most extreme. This situation is critical for air traffic controllers, as it helps ensure safe separation between aircraft.

Understanding this distinction is essential for maintaining situational awareness in busy airspace, where avoiding conflict between aircraft requires knowledge of their relative courses. The definition also implies that the protected airspaces of these flights may be overlapping, which is relevant for ensuring that aircraft do not enter each other's zones.

In contrast, other choices like "Same Courses" and "Crossing Courses" either pertain to situations with smaller angle differences or differing flight dynamics. Therefore, recognizing the definition of "Opposite/Reciprocal Courses" is essential for effective en-route radar control and for establishing safe operability within controlled airspace.