What must be true for aircraft assigned 5 miles separation?

When assigned 5 miles of separation, it is crucial that the separation between the aircraft must be constant or increasing. This requirement ensures that the distance between the two aircraft does not decrease, which is essential for maintaining safety and minimizing the risk of mid-air collisions. Constant or increasing separation provides a reliable buffer, allowing for variations in flight paths, speeds, or other factors that can affect the distance between aircraft as they approach one another.

Other options misrepresent requirements or conditions that are not necessary for the maintenance of appropriate separation. For instance, while being on final approach can contribute to an organized flow of air traffic, it is not a definitive criterion for maintaining 5 miles of separation. Similarly, aircraft type does not directly relate to the need for separation, as different types can safely operate at set distances depending on the circumstances. Lastly, diverging aircraft may still meet the requirement of maintaining 5 miles of separation, especially if the separation is being preserved or increasing.