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Aeronautical Chart Users’ Guide

FAA Chart Users’ Guide Version 9 July 2026
All Library Documents

IFR Enroute Low/High Altitude Symbols

IFR low- and high-altitude enroute chart legends, symbols, examples, and procedures.

FAA aeronautical chart visual associated with “Special Use Airspace - U.S.” (source page 92).
Special Use Airspace - U.S. — source page 92.
FAA aeronautical chart visual associated with “Special Use Airspace - U.S.” (source page 92).
Special Use Airspace - U.S. — source page 92.
AIRSPACE INFORMATION (Continued) Special Use Airspace - U.S. Low and High Charts Low Charts Only P - Prohibited Area R - Restricted Area W - Warning Area See Airspace Tabulation on each chart for complete documentation information on: Area Identification Effective Altitude Operating Times Controlling Agency Voice Call A - Alert Area * Alert Areas do not extend into Class A, B, C and D airspace, or Class E airport surface areas. MOA - Military Operations Area See Airspace Tabulation on each chart for complete documentation information on: Area Identification Effective Altitude Operating Times Controlling Agency Voice Call Example: P-56 - Washington DC, Area A-1 Chart Example: P-40 and R-4009 - Washington DC, Area A-1 Chart Example: R3601A - Example: W-50
Source page 93

AIRSPACE INFORMATION (Continued)

Off Route Obstruction Clearance Altitude (OROCA)

OROCA is computed similarly to the Maximum Elevation Figure (MEF) found on Visual charts except that it provides an additional vertical buffer of 1,000 feet in designated non-mountainous areas and a 2,000 foot vertical buffer in designated mountainous areas within the United States.
Example: 12,500 feet
FAA aeronautical chart visual associated with “Example: 12,500 feet” (source page 93).
Example: 12,500 feet — source page 93.
FAA aeronautical chart visual associated with “Off Route Obstruction Clearance Altitude example — Low L-13 Chart” (source page 93).
Off Route Obstruction Clearance Altitude example — Low L-13 Chart — source page 93.

Special Flight Rules Area (SFRA)

FAA aeronautical chart visual associated with “Special Flight Rules Area (SFRA)” (source page 93).
Special Flight Rules Area (SFRA) — source page 93.
FAA aeronautical chart visual associated with “Washington SFRA low-chart example” (source page 93).
Washington SFRA low-chart example — source page 93.
FAA aeronautical chart visual associated with “Washington, D.C. Special Flight Rules Area example — High Chart H-12” (source page 93).
Washington, D.C. Special Flight Rules Area example — High Chart H-12 — source page 93.
AIRSPACE INFORMATION (Continued) Off Route Obstruction Clearance Altitude (OROCA) Low Charts Only OROCA is computed similarly to the Maximum Elevation Figure (MEF) found on Visual charts except that it provides an additional vertical buffer of 1,000 feet in designated non-mountainous areas and a 2,000 foot vertical buffer in designated mountainous areas within the United States. Example: 12,500 feet Example: Low L-13 Chart Special Flight Rules Area (SFRA) Low and High Charts SFRA Symbology Example: Low Chart (Washington Area Chart) Example: High Chart (H-12)
Source page 94

NAVIGATIONAL AND PROCEDURAL INFORMATION

Cruising Altitudes - Low Charts - U.S. Only

IFR outside controlled airspace.
FAA aeronautical chart visual associated with “IFR within controlled airspace as assigned by ATC.” (source page 94).
IFR within controlled airspace as assigned by ATC. — source page 94.