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SESK: Stuff Everyone Should Know · sesk.info/sport-class-c-core

Class C airspace has an inner surface core with what radius?

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

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  1. 5 NM ✔
  2. 10 NM
  3. 3 NM

Why: Class C has a 5 NM radius core from the surface and a 10 NM radius shelf that starts no lower than 1,200 feet. It surrounds airports with a control tower and radar approach control.

Huh, didn't know that: Class C generally extends from the surface to 4,000 feet above the airport elevation.

The dad joke
Class C airspace is a layer cake: a 5 NM core, then a 10 NM shelf for frosting.
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References

Answer: 5 NM. Class C has a 5 NM radius core from the surface and a 10 NM radius shelf that starts no lower than 1,200 feet. It surrounds airports with a control tower and radar approach control.

  1. FAA AIM 3-2-4, Class C Airspace www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.html
    a 5 NM radius core surface area
    Checked 2026-10-11.
  2. FAA AIM 3-2-4, Class C Airspace www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.html
    extends from the surface up to 4,000 feet above the airport elevation
    Checked 2026-10-11.

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