In a non-radar environment, how many minutes should a departure take off before an arriving aircraft if there is no approach control and the takeoff direction differs by at least 45° from the final approach course?

In a non-radar environment, ensuring the safe separation of aircraft is critical, especially during takeoff and landing operations. When considering a departure that will take off in a direction that differs by at least 45 degrees from the final approach course of an arriving aircraft, a mandatory time interval is established to maintain appropriate separation.

The correct choice indicates that a departure should take off at least three minutes before an arriving aircraft in this scenario. This time is necessary to provide a sufficient buffer, accounting for potential variations in flight paths and the time it takes for the departing aircraft to gain altitude and distance from the approach path of the arriving aircraft. The three-minute interval helps mitigate the risk of wake turbulence and ensures that the departing aircraft is at a safe distance from the flight path of the arriving aircraft.

In a non-radar environment, accurate timing is essential since real-time tracking of aircraft is not available, and the air traffic controller must rely on established separation criteria to ensure safety. The required three-minute gap is a measure that reflects these operational concerns, leading to safe and effective air traffic management.