When a sector 66 arrival conflicts with an overflight and vertical separation is used, what must happen?

• A. The arrival must hold until the overflight passes.
• B. The arrival must either be moved under the overflight or the overflight must climb above the arrival.
• C. The overflight must descend below the arrival.
• D. The arrival must be diverted to another sector.

Answer: (B)

When two aircraft could conflict, vertical separation means keeping them on different flight levels so there’s a clear altitude gap between them. If a sector 66 arrival is in conflict with an overflight and you’re using vertical separation, you must reestablish that altitude difference. The way to do this is to place the arrival beneath the overflight or to have the overflight climb above the arrival. In other words, assign altitudes so the two are in distinct layers.

Holding the arrival while the overflight passes is not the required fix, and diverting the arrival to another sector is an extra option for flow or routing, not the direct method to maintain vertical separation in this situation.