What type of airport is indicated by a black circle with an "A" on sectional charts?

The black circle with an "A" on sectional charts indicates an abandoned airport. This is important for pilots using sectional charts to recognize areas that may have previously had aviation activity but are no longer in operation. Knowing that an airport is abandoned means a pilot should be cautious when flying in the vicinity, as the area may not have current air traffic control services or operational procedures in place.

While it is true that the other options represent different types of airports, they do not accurately describe what the black circle with an "A" signifies. For instance, military airports, private airports, and airports with active control towers are represented differently on sectional charts, utilizing distinct symbols and features to help pilots easily identify their status and operational capabilities. Thus, recognizing the specific symbol for abandoned airports helps ensure that pilots have the right situational awareness when navigating near these areas.