Private Pilot Private Practice Exam

The correct answer is determined by the structure of Class C airspace, which typically has a defined outer area with a radius of 20 nautical miles (NM). This outer area serves as a transition zone for aircraft preparing to enter the inner core of the Class C airspace, which is designed for the arrival and departure of larger aircraft at busy airports.

The 20 NM radius allows for adequate separation and management of air traffic, ensuring that aircraft outside of the core can be effectively monitored and controlled as they approach the airspace. It also provides an appropriate buffer zone where pilots are encouraged to establish communication with air traffic control, enhancing safety during transitions into more congested airspace.

The other options, while representing distances that could conceptually be considered for airspace dimensions, do not align with the established regulations and aeronautical guidelines set by the FAA for Class C airspace. Understanding these dimensions and the structure of controlled airspace is crucial for ensuring safe operations and compliance with air traffic regulations.