What is the typical radius of the uncharted Outer Area of Class C airspace?

The uncharted Outer Area of Class C airspace typically extends from the surface to a vertical limit of 4,000 feet above the airport elevation, and usually has a radius of 20 nautical miles from the airport. This designation is crucial for managing air traffic around busy airports, providing necessary structure for both arriving and departing aircraft while also ensuring that air traffic control can effectively supervise operations in these high-traffic areas.

The options provided relate to various radii that might be encountered in airspace structure, but the specific standard for the uncharted Outer Area of Class C airspace is indeed 20 nautical miles. This allows for a buffer zone that helps in the separation and management of different types of air traffic, enhancing safety and efficiency in operations.