One In or One Out
Before I can clear an airplane for a visual approach, I have to ensure the pilot has either the landing runway, the airport, or preceding aircraft in sight. Obvious, right? If youre landing on it or following it, ATC must ensure you can see it. For instance, if there are clouds in the way or the preceding aircraft gets lost in ground clutter or weather, theres no guarantee youll be able to safely navigate visually to the runway.