Separate Category E through I aircraft landing behind a departing Category B, C, or D aircraft on a crossing runway if the arrival will fly through the airborne path of the departure by a minimum of ___ minutes or the appropriate radar separation minima.

• A. 1
• B. 3
• C. 4
• D. 2

Answer: (D)

When an arriving aircraft would pass through the airborne path of a departing aircraft on a crossing runway, you use a fixed time-based separation to keep their paths from intersecting. The standard minimum is two minutes, or the corresponding radar separation minima if that is greater. This two-minute gap is chosen because it provides a reliable buffer for the departure to climb out and move clear of the crossing path, reducing the chance of a conflict during the transition from takeoff to the initial climb and the arrival’s approach. In practice, you apply whichever separation is larger—in some situations the radar-based minimum may exceed two minutes, and you would use that. This rule helps ensure safe sequencing for aircraft in the common mixed-use scenario on crossing runways.