Which pair of airspace classes both require ATC clearance?

• A. Class A and Class G
• B. Class A and Class E
• C. Class C and Class D
• D. Class E and Class G

Answer: (C)

ATC clearance is required to enter airspace that is controlled and actively managed by air traffic control. Class C and Class D are both such controlled airspaces around busy airports, and pilots must obtain ATC clearance before entering and maintain two-way radio communication with ATC while operating there. In contrast, Class E and Class G either do not require entry clearance for VFR (Class E) or are uncontrolled (Class G), so they don’t fit the requirement. Therefore, the pair where entry requires ATC clearance is Class C and Class D.