Airspace Classes

Six classes (A–E controlled, G uncontrolled) plus special-use overlays. Each class has its own entry rules, equipment requirements, and speed limits. The PPL standard is being able to identify any chart-depicted airspace at a glance and recite its rules cold. Reference: AIM Chapter 3 — Airspace and 14 CFR Part 71.

Class A — § 71.33

Vertical limits: 18,000 ft MSL up to FL600.
Entry: IFR clearance only — no VFR ops permitted.
Equipment: Two-way radio, Mode C transponder, ADS-B Out (per § 91.225).
Helicopter operations in Class A are rare — most civil rotorcraft don't have the service ceiling. Some twins (S-92, AW139) operate IFR in Class A on offshore platform routes.

Class B — § 71.41

Around major hubs (~37 in the US — JFK, LAX, ATL, etc.). Inverted "wedding cake" with shelves at progressively higher floors moving outward.
Entry: ATC clearance required — must hear "Cleared into the Class Bravo." A handoff or "radar contact" alone is not a clearance.
Equipment: Two-way radio, Mode C transponder, ADS-B Out.
Pilot certificate: Private (or student with required endorsement per § 61.95); solo students may not operate to/from the listed Class B primary airports in FAA Order JO 7400.2 Appendix 4.
Speed limits: 250 KIAS within Class B; 200 KIAS under the shelf or in a VFR corridor (per § 91.117).
VFR weather mins: 3 SM, clear of clouds.

Class C — § 71.51

Around medium-traffic airports with a tower, radar approach control, and certain traffic counts. Two-ring "wedding cake" — 5 NM core (surface to 4,000 AGL) + 10 NM outer ring (1,200–4,000 AGL).
Entry: Two-way radio contact with the controlling facility. Clearance is not explicitly required — but if the controller doesn't say your N-number, you don't have contact.
Equipment: Two-way radio, Mode C transponder, ADS-B Out.
Speed limits: 200 KIAS within 4 NM of the primary airport at or below 2,500 AGL.
VFR weather mins: 3 SM, 1,000/500/2,000 (1 below / 500 above / 2,000 horizontal).

Class D — § 71.61

Around tower-controlled airports without radar approach control. Typically a 4–5 NM radius cylinder, surface to 2,500 AGL.
Entry: Two-way radio contact before entering. Same "your N-number must be acknowledged" rule as Class C.
Equipment: Two-way radio. No transponder required (unless within a Class B/C Mode C veil).
Speed limits: 200 KIAS at or below 2,500 AGL within 4 NM of the primary airport.
VFR weather mins: 3 SM, 1,000/500/2,000.
Class D becomes Class E (or G) when the tower closes — listen to ATIS for the part-time hours.

Class E — § 71.71

Controlled airspace not designated A, B, C, or D. Most en route airspace in the US is Class E.
Floors:
- Surface (around airports with instrument approaches, dashed magenta border)
- 700 AGL (faded magenta vignette, around most uncontrolled airports)
- 1,200 AGL (faded blue vignette — the default away from airports)
- 14,500 MSL (everything above this is Class E up to 18,000 unless otherwise designated)
Entry: No clearance or contact required for VFR — but you must meet the weather minimums per § 91.155.
VFR weather mins (below 10,000 MSL): 3 SM, 1,000/500/2,000.
VFR weather mins (at and above 10,000 MSL): 5 SM, 1,000 above / 1,000 below / 1 SM horizontal.

Class G — uncontrolled

Below the Class E floor — surface to 700 AGL or 1,200 AGL depending on the chart.
No ATC service. No clearance or contact required for VFR or IFR (yes, IFR in Class G is legal — just unwise without ATC).
VFR weather mins (day, ≤ 1,200 AGL): 1 SM, clear of clouds. Helicopters: 1/2 SM clear of clouds.
VFR weather mins (night, ≤ 1,200 AGL): 3 SM, 1,000/500/2,000. Helicopters at speeds permitting see-and-avoid: 1 SM, clear of clouds.
Above 1,200 AGL Class G transitions back to standard mins (3 SM, 1,000/500/2,000 day; 3/1k/500/2k night).

Full helicopter exception detail on VFR Weather Minimums.

Mode C veil & ADS-B rule

Mode C veil: 30 NM lateral around any Class B primary airport (per § 91.215) — Mode C transponder required regardless of altitude or whether you enter the Bravo itself.
ADS-B Out (§ 91.225): Required in Class A; in Class B and C; in the Mode C veil; in Class E at and above 10,000 MSL (excluding airspace at and below 2,500 AGL); above the ceiling and within the lateral boundaries of Class B/C up to 10,000 MSL; over the Gulf of Mexico above 3,000 MSL within 12 NM of the coast.
Most light helicopters now carry an ADS-B Out installation — confirm IFR/VFR capability with your specific avionics.