Define the control zone.

• A. 3 NM radius surface up to 1500 ft
• B. 10 NM radius surface up to 500 ft
• C. 7 NM radius surface up to 3000 ft
• D. 5 NM radius surface up to and including 2500 ft

Answer: (D)

A control zone is the airspace surrounding an aerodrome established to provide ATC protection for aircraft during the critical phases of flight, especially arrivals, departures, and circuit operations.

The typical depiction is a 5 nautical mile radius around the aerodrome, extending from the surface up to and including 2500 feet above the aerodrome elevation. This compact volume ensures ATC can manage traffic right at the field without having to extend into higher-altitude airspace.

The other options describe dimensions that don’t align with this common definition: they propose different radii or vertical extents that would either give too much space or not cover the essential low-altitude, around-the-field operations. Therefore, the 5 NM radius from the surface to 2500 ft is the best match for defining a control zone.