In the context of visual separation, what must the tower ensure regarding the aircraft?

In the context of visual separation, the tower must ensure that the aircraft are visually observed. This is crucial because visual separation relies on the pilots’ and controllers’ ability to see the aircraft and confirm their positions relative to one another. The procedure allows pilots to maintain spacing by relying on their visual observations rather than strict reliance on radar and separation standards.

When aircraft are visually observed, the controller can confidently issue instructions based on the pilots' awareness of each other's locations, enhancing safety by confirming that the required separation exists as perceived by those involved. This practice supports situational awareness, allowing pilots to make timely decisions about their operations, thus reducing the risk of conflict.

In contrast, while ensuring aircraft are above the minimum safe altitude is important for overall safety, it does not relate specifically to visual separation. Proximity and communication are also vital for safe flight operations, but the key aspect of visual separation is the confirmation that all aircraft involved are actively observed visually, ensuring the separation can be maintained without relying solely on technological systems.