What is the typical ceiling of Class C airspace?

• A. 2000 ft AGL
• B. 4000 ft AGL
• C. 6000 ft AGL
• D. 10000 ft MSL

Answer: (B)

The ceiling of Class C airspace is typically 4,000 ft above the airport, described as 4,000 ft AGL. This structure usually consists of an inner core from the surface up to 4,000 ft AGL and an outer shelf from about 1,200 ft up to 4,000 ft AGL. The reason this ceiling is set at 4,000 ft AGL is to provide controlled protection around busy terminals while still allowing VFR traffic to enter with ATC clearance and without stepping into higher controlled airspace. If you know the airport’s elevation, you can convert to MSL by adding that elevation to 4,000 ft; for example, an airport at 1,000 ft elevation would have a ceiling around 5,000 ft MSL.