What angle is critical for ensuring separation of aircraft on diverging radials?

The critical angle for ensuring separation of aircraft on diverging radials is 15 degrees. This angle is pivotal in air traffic control for maintaining safe separation between aircraft navigating along paths that diverge from a common point. When aircraft are given instructions to diverge from a fix or a waypoint, a 15-degree divergence helps minimize the risk of conflict and ensures that aircraft can safely spread out while ascending, descending, or cruising.

At angles larger than 15 degrees, the paths of aircraft can spread out more rapidly, which enhances safety but could potentially lead to inefficiencies in airspace utilization. On the other hand, angles less than 15 degrees may not create sufficient separation, increasing the risk of converging paths and potential conflicts. Therefore, utilizing a 15-degree angle allows air traffic controllers to optimize the balance between safety and efficiency in managing aircraft routes.