Aeronautical chart conventions (United States)

This article describes the graphic conventions used in Sectional charts and Terminal area charts published for aeronautical navigation under Visual Flight Rules in the United States of America. The charts are published "in accordance with Interagency Air Cartographic Committee specifications and agreements, approved by the Department of Defense and the Federal Aviation Administration".

The legend of an aeronautical chart lists many of the symbols, colors and codes used to convey information to the map reader.

General

A sectional chart is a two-sided chart created from a Lambert Conformal Conic Projection with two defined standard parallels. The scale is 1:500,000, with a contour interval of 500 feet. The size of each sectional is designed to be "arm's width" when completely unfolded. The "northern" half of the section is on one side of the chart, and the "southern" on the obverse. The edges between north and south are designed with a calibrated overlap that permits plotting extensions of course lines from one side to the other, once the user has scribed a corresponding "match line" on each side. All other edges are truncated at a predetermined size. White space around the chart is filled with map information and the legend, scales, and tables of airport and airspace information.

Terrain is color-coded for its elevation and major roads, cities, and bodies of water are shown for visual reference, as well as other identifiable structures (e.g., stadiums and water towers). However, most of the layers of data on the charts include specific information about obstacles, airspace designations, and facility information (locations, radio frequencies, etc.).

The legend divides these into several types of information, namely: airports, radio aids, traffic and airspace services, obstructions, topographic, and miscellaneous.

Other unusual features may be designated on the map with symbols that do not appear in the legend, such as areas where laser lights are routinely pointed into the air (a jagged-edged circle), or a wildlife protection area (a solid line with dots along the inside edge).

Airports

The location of each airport and presence of control towers is indicated with a circle, or with an outline of the hard-surfaced runways (if over 8,069 feet long). Blue shows an airport with a control tower and magenta for others.

Airport data

Each indicated airport has an airport data block associated with it. The block may contain just the name, altitude and runway length, or any of the following additional information, among others.

Radio Aids and Communication Boxes

Airport Traffic and Airspace Information

Obstructions

Tall towers are especially dangerous and have specific markings according to their height above ground and whether or not lighted.

Topographic Information

Based upon standard mapping symbols, these markings usually designate man-made structures that may be identifiable from the air, including:

Where relevant, a mountain pass and its elevation may be shown with curved lines.

Miscellaneous

Some indicators do not cleanly fall into the previous categories. These include:

References

    External links

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