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AhaBulb: Stuff Everyone Should Know · ahabulb.com/pilot-class-c-core-5nm

The Class C surface area core usually has what radius around the primary airport?

5 nautical miles, with a 10 NM shelf above it.

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  1. 10 nautical miles
  2. 5 nautical miles ✔
  3. 20 nautical miles

Why: The AIM describes Class C as a 5 NM core from the surface to 4,000 feet above the airport, plus a 10 NM shelf starting no lower than 1,200 feet. 20 NM is the outer area, which is not Class C airspace.

Huh, didn't know that: Sectional charts print Class C floor and ceiling altitudes in magenta, with the last two zeros left off.

The dad joke
What do you call Class C airspace from the side? An upside down wedding cake.
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References

Answer: 5 nautical miles. The AIM describes Class C as a 5 NM core from the surface to 4,000 feet above the airport, plus a 10 NM shelf starting no lower than 1,200 feet. 20 NM is the outer area, which is not Class C airspace.

  1. AIM 3-2 Controlled Airspace (Class C) www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.html
    5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation
    Checked 2026-10-07.

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