AIM ¶ 3-2-4 — Class C Airspace
AIM 3-2-4 explains Class C airspace dimensions, two-way radio and transponder/ADS-B requirements, entry procedures, speed limits, and ATC services for pilots.
Class C airspace surrounds busier airports that have an operational control tower, radar approach control, and meet certain IFR/passenger thresholds. Although tailored to each location, the typical shape is:
- A 5 NM radius surface core from the surface up to 4,000 feet AGL (charted in MSL)
- A 10 NM radius shelf from 1,200 feet AGL up to 4,000 feet AGL
- A 20 NM procedural Outer Area (not charted) where Class C services are also available
Pilot/equipment requirements:
- No specific pilot certification required
- Two-way radio communication established with ATC before entry, and maintained while inside
- Operable Mode C transponder with altitude reporting and ADS-B Out (unless ATC authorizes otherwise)
Communication tip: If ATC replies using your callsign (even just "N123AB, standby"), two-way comms are established and you may enter. If they say "aircraft calling, standby" without your callsign, you may not enter.
Speed: Below 2,500 ft AGL within 4 NM of the primary airport, max 200 knots indicated.
Within Class C, ATC sequences VFR traffic to the primary airport and separates VFR from IFR using visual separation, 500 ft vertical, or target resolution. Pilots remain responsible for see-and-avoid, terrain/obstacle clearance, wake turbulence avoidance, and VFR weather minimums per 14 CFR 91.155.
Five FAA-written-style questions. Instant explanations, every answer cites its source — no account needed.
You are flying VFR in Class E airspace at 8,500 feet MSL during the day. What are your minimum visibility and cloud clearance requirements?