US airspace classes explained (A through G)
A plain-English tour of the US airspace system — Classes A, B, C, D, E and G — and what each means for VFR and IFR pilots.
US airspace is divided into classes that set the rules for who may enter, what equipment and clearances are required, and the weather minimums that apply. They fall into two buckets: controlled (A, B, C, D, E) where ATC provides separation or traffic service, and uncontrolled (G) where pilots are on their own.
- Class A — 18,000 ft MSL up to FL600. IFR only; everyone is on an instrument clearance.
- Class B — the busiest airports (think Los Angeles, Atlanta). An ATC clearance to enter is mandatory, even VFR.
- Class C — mid-size airports with a control tower and radar. Two-way radio contact and a transponder required.
- Class D — smaller towered airports. Two-way radio contact required; a surface-based cylinder usually to 2,500 ft AGL.
- Class E — controlled airspace that isn't A/B/C/D. It fills the gaps so IFR traffic stays in controlled airspace; VFR pilots need no clearance but must meet cloud-clearance rules.
- Class G — uncontrolled airspace, typically near the surface in rural areas. No ATC clearance; the loosest weather minimums.
The class determines three things: entry requirements (clearance/radio/transponder), VFR weather minimums (visibility and distance from clouds), and separation services. Knowing which class you're in — and how it's depicted on a sectional chart — is fundamental airmanship.
*Reference and training only. Always consult current charts and the FAA AIM.*