The normal vertical limit of Class C airspace above the primary airport is normally

The normal vertical limit of Class C airspace above the primary airport is normally

• A. 4,000 feet AGL
• B. 4,000 feet MSL
• C. 3,000 feet AGL
• D. 5,000 feet AGL

Answer: (A)

In Class C airspace, the vertical extent is defined relative to the primary airport. The inner core sits from the surface up to a fixed top height above the airport, and the outer shelf shares that same top height. That top is four thousand feet above the airport’s elevation, which at the airport location translates to four thousand feet above the ground (four thousand feet AGL). So the normal upper boundary above the primary airport is four thousand feet above the airport. Why not the other figures? Using mean sea level would ignore the airport’s elevation and terrain differences, and four thousand feet above the airport is the standard cap, not three thousand or five thousand feet.

In Class C airspace, the vertical extent is defined relative to the primary airport. The inner core sits from the surface up to a fixed top height above the airport, and the outer shelf shares that same top height. That top is four thousand feet above the airport’s elevation, which at the airport location translates to four thousand feet above the ground (four thousand feet AGL). So the normal upper boundary above the primary airport is four thousand feet above the airport.

Why not the other figures? Using mean sea level would ignore the airport’s elevation and terrain differences, and four thousand feet above the airport is the standard cap, not three thousand or five thousand feet.