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Airspaces and A/FD


Airport/Facility Directory

Airport/Facility Directory (A/FD) refers to the front section of the Chart Supplement publication. This is where the airports, NAVAIDs, and weather devices are listed. "Chart Supplement" refers to the entire volume.

IFR Low Altitude Enroute Charts

IFR Low Altitude Enroute Charts provide aeronautical information for navigation under instrument flight rules below 18,000 feet MSL.
These four-color chart series includes:
Air Traffic Services | Airports that have an Instrument Approach Procedure or a minimum 3000' hard surface runway | Airways/Route Data | Cruising Altitudes | Fixes/ATC Reporting Points | Limits of controlled airspace | Military Training Routes | Off Route Obstruction Clearance Altitudes (OROCA) | Radio aids to navigation | RNAV Routes | Special Use Airspace Areas | Tabulations (MTRs, SUAs, MOAs, Airport data)

Lettered Airspaces

Airspace classes are identified by letter: A, B, C, D, E, and G. A through E are controlled. Class G is uncontrolled.

Of the controlled airspaces, Class B, C, and D surround towered airports. Although dimensions vary, here are the standard limits:
Class B - 10,000 MSL; 30 NM radius
Class C - 4,000 AGL; 10 NM radius
Class D - 2,500 AGL; 4.4 NM radius

Class A airspace covers the entire continent, but never touches the ground. Class A begins at 18,000 feet MSL and continues upward. Think of “A” for “altitude.” You must have an IFR clearance in Class A. Class A is all airspace above 17,999 feet MSL, up to and including Flight Level 600.