Aviation Training Experts™

other

Aeronautical Chart Users’ Guide

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

Explanation of IFR Enroute Terms

Searchable explanations of IFR enroute airports, radio aids, airspace, airways, foreign areas, and terrain contours.

Source page 63

Explanation of IFR Enroute Terms

FAA charts are prepared in accordance with specifications of the Interagency Air Committee (IAC), and are approved by representatives of the Federal Aviation Administration and the Department of Defense (DoD). Some information on these charts may only apply to military pilots.
The explanations of symbols used on Instrument Flight Rule (IFR) Enroute Charts and examples in this section are based primarily on the IFR Enroute Low Altitude Charts. Other IFR products use similar symbols in various colors. The chart legends portray aeronautical symbols with a brief description of what each symbol depicts. This section provides more details of the symbols and how they are used on IFR Enroute charts.

AIRPORTS

Operational airports are shown on IFR Enroute Charts.
Low Charts:
  • All IAP Airports are shown on the Low Altitude Charts (US and Alaska).
  • Non-IAP Airports are shown on the U.S. Low Altitude Charts (Contiguous US) have a minimum hard surface runway of 3,000’.
  • Non-IAP airports are shown on the U.S. Low Altitude Alaska Charts are show if the runway is 3000’ or longer, hard or soft surface.
  • Public heliports with an Instrument Approach Procedure (IAP) or requested by the FAA or DoD are depicted on the IFR Enroute Low Altitude Charts.
  • Seaplane bases requested by the FAA or DoD are depicted on the IFR Enroute Low Altitude Charts.
On IFR Enroute Low Altitude Charts, airport tabulation is provided that identifies airport names, IDs and the panels they are located on.
High Charts:
  • Airports shown on the U.S. High Enroute Charts (Contiguous US) have a minimum hard surface runway of 5000’.
  • Airports shown on the U.S. High Enroute Alaska Charts have a minimum hard surface runway of 4000’.
Charted airports are classified according to the following criteria:
LOW/HIGH ALTITUDE
FAA aeronautical chart visual associated with “Low/high-altitude civil-airport symbols — blue, green, brown” (source page 63).
Low/high-altitude civil-airport symbols — blue, green, brown — source page 63.
Airports are plotted at their true geographic position.
Airports are identified by the airport name. In the case of military airports, Air Force Base (AFB), Naval Air Station (NAS), Naval Air Facility (NAF), Marine Corps Air Station (MCAS), Army Air Field (AAF), etc., the abbreviated letters appear as part of the airport name.
EXPLANATION OF IFR ENROUTE TERMS FAA charts are prepared in accordance with specifications of the Interagency Air Committee (IAC), and are approved by representatives of the Federal Aviation Administration and the Department of Defense (DoD). Some information on these charts may only apply to military pilots. The explanations of symbols used on Instrument Flight Rule (IFR) Enroute Charts and examples in this section are based primarily on the IFR Enroute Low Altitude Charts. Other IFR products use similar symbols in various colors. The chart legends portray aeronautical symbols with a brief description of what each symbol depicts. This section provides more details of the symbols and how they are used on IFR Enroute charts. AIRPORTS Operational airports are shown on IFR Enroute Charts. Low Charts: • All IAP Airports are shown on the Low Altitude Charts (US and Alaska). • Non-IAP Airports are shown on the U.S. Low Altitude Charts (Contiguous US) have a minimum hard surface runway of 3,000’. • Non-IAP airports are shown on the U.S. Low Altitude Alaska Charts are show if the runway is 3000’ or longer, hard or soft surface. • Public heliports with an Instrument Approach Procedure (IAP) or requested by the FAA or DoD are depicted on the IFR Enroute Low Altitude Charts. • Seaplane bases requested by the FAA or DoD are depicted on the IFR Enroute Low Altitude Charts. On IFR Enroute Low Altitude Charts, airport tabulation is provided that identifies airport names, IDs and the panels they are located on. High Charts: • Airports shown on the U.S. High Enroute Charts (Contiguous US) have a minimum hard surface runway of 5000’. • Airports shown on the U.S. High Enroute Alaska Charts have a minimum hard surface runway of 4000’. Charted airports are classified according to the following criteria: LOW/HIGH ALTITUDE Blue - Airports with an Instrument Approach Procedure and/or RADAR MINIMA published in the high altitude DoD Flight Information Publications (FLIPs) Green - Airports that have an approved Instrument Approach Procedure and/or RADAR MINIMA published in either the U.S. Terminal Procedures Publications (TPPs) or the DoD FLIPs Brown - Airports without a published Instrument Approach Procedure or RADAR MINIMA Black - Foreign airports Airports are plotted at their true geographic position. Airports are identified by the airport name. In the case of military airports, Air Force Base (AFB), Naval Air Station (NAS), Naval Air Facility (NAF), Marine Corps Air Station (MCAS), Army Air Field (AAF), etc., the abbreviated letters appear as part of the airport name.
Source page 64
Airports marked "Pvt" immediately following the airport name are not for public use, but otherwise meet the criteria for charting as specified above.
Runway length is the length of the longest active runway (including displaced thresholds but excluding overruns) and is shown to the nearest 100 feet using 70 feet as the division point; e.g., a runway of 8,070' is labeled 81. The following runway compositions (materials) constitute a hard-surfaced runway: asphalt, bitumen, chip seal, concrete, and tar macadam. Runways that are not hard-surfaced have a small letter "s" following the runway length, indicating a soft surface.