What are the dimensions of Class C airspace?

Class C airspace is typically defined as having a 5 nautical mile (NM) radius around the airport up to an altitude of 4,000 feet above ground level (AGL). This type of airspace is designed to provide controlled airspace for airports with a certain amount of commercial traffic, ensuring safety and efficiency in and around the terminal area.

The dimensions of Class C airspace are structured to help manage aircraft movement while allowing for sufficient room for aircraft to operate safely. The 5 NM radius ensures that aircraft entering or exiting the airspace can be adequately monitored and controlled by air traffic controllers, while the vertical limit up to 4,000 feet AGL provides enough clearance for various flight operations without encroaching on nearby airspace categories.

This structure is essential for maintaining safety, as it allows for the separation of aircraft movements, reducing the risk of mid-air collisions. Therefore, the defining characteristic of Class C airspace as a 5 NM radius from the airport surface up to 4,000 feet AGL makes option B the correct choice.