Module MOD-08 · 6 min · ACS PA.I.E

The Airspace System at a Glance

← Airspace and Operating Requirementsdraft — pending CFI review

Why this matters in flight: Knowing which airspace you are in tells you who you must talk to, what equipment you need, and what weather you legally need to fly. Getting this wrong can put you into airspace you are not cleared for.
Cross-section of US airspace classesA vertical cross-section showing Class A above 18,000 feet MSL for IFR only, Class B as a stepped upside-down wedding cake up to 10,000 feet MSL, Class C up to about 4,000 feet above ground, Class D up to about 2,500 feet above ground, Class E controlled airspace overlying with 700 or 1,200 foot floors, and Class G uncontrolled airspace at the surface.18,000 MSL10,000 MSL4,000 AGL2,500 AGL1,200 AGLSurfaceCLASS Econtrolled, 700/1,200 AGL floorCLASS A — 18,000 MSL to FL600 — IFR onlyCLASS BCLASS CCLASS DCLASS G (uncontrolled)
DRAFT schematic — pending CFI review. Not to scale; floors and ceilings vary by location. Not an FAA-approved figure.

US airspace is divided into controlled and uncontrolled airspace. Controlled airspace is where air traffic control can provide separation and services; it is labeled Classes A, B, C, D, and E. Uncontrolled airspace is Class G. A simple way to remember the controlled classes is that they run from the most restrictive (Class A, high altitude, instrument flight only) down to the least restrictive controlled class (Class E). Class G sits underneath, closest to the ground, where ATC does not separate traffic and you are responsible for seeing and avoiding other aircraft. As a VFR private pilot you will spend most of your time in Classes E and G, occasionally transiting B, C, or D near busier airports.

Key terms

Controlled airspace
Airspace where ATC service is available: Classes A, B, C, D, E.
Uncontrolled airspace
Class G, where ATC does not separate traffic.
MSL / AGL
Altitude above mean sea level versus above ground level.

Summary

Controlled airspace is Classes A–E; uncontrolled airspace is Class G. VFR private pilots mostly operate in E and G and transit B/C/D near busy airports.

Quick check ▾

One question on what you just read.

Question 1 of 1

Objective mastery: 15%

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Class A airspace generally begins at which altitude?

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Sources

Every claim traces to a source — paraphrased knowledge elements pointing at the governing FAA publication; not yet verified against a retrieved source.

  • 14 CFR 71 / AIM 3-2-2 — 14 CFR Part 71 — Designation of Airspace unverified
  • AIM 3-2-6 / 14 CFR 71 — Aeronautical Information Manual unverified
  • AIM 3-3-1 / 14 CFR 91.155 — Aeronautical Information Manual unverified

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