What must be in sight for an accepted visual approach?

For a visual approach to be accepted, it is crucial that the airport is in sight. This requirement ensures that the pilot can safely navigate towards the airport and make necessary adjustments to the approach and landing as they are visualizing the environment around them. Being able to see the airport allows the pilot to gauge their position and prepare for landing, ensuring situational awareness during the approach phase.

The other options, while important in certain contexts, do not fulfill the essential requirement for initiating a visual approach. The runway must be visible but is typically a part of the larger airport area that a pilot must see first. Other aircraft are important to monitor for safety but do not impact the ability to conduct a visual approach on their own. Ground markings provide helpful information but are not a primary requirement for a visual approach. Having the airport in sight is the key factor that demonstrates a pilot's readiness to land visually.