Aeronautical Chart Conventions (United States)
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This article describes the graphic conventions used in
Sectional chart In United States aviation, a sectional aeronautical chart, often called a sectional chart or a sectional for short, is a type of aeronautical chart designed for air navigation under visual flight rules (VFR). In Australia, Canada and some other ...
s and
Terminal area chart In United States and Canada aviation, terminal area charts are aeronautical charts intended for navigation under Visual Flight Rules that depict areas surrounding major airports, primarily those with Class B airspace. Overview Like the VFR sect ...
s published for aeronautical
navigation Navigation is a field of study that focuses on the process of monitoring and controlling the motion, movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navig ...
under
Visual Flight Rules In aviation, visual flight rules (VFR) is a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better tha ...
in the
United States of America The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguo ...
. The charts are published "in accordance with Interagency Air Cartographic Committee specifications and agreements, approved by the
Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, ...
and the
Federal Aviation Administration The Federal Aviation Administration (FAA) is a Federal government of the United States, U.S. federal government agency within the United States Department of Transportation, U.S. Department of Transportation that regulates civil aviation in t ...
". The legend of an
aeronautical chart An aeronautical chart is a map designed to assist in the navigation of aircraft, much as nautical charts do for watercraft, or a roadmap does for drivers. Using these charts and other tools, pilots are able to determine their position, safe alt ...
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 A Lambert conformal conic projection (LCC) is a conic map projection used for aeronautical charts, portions of the State Plane Coordinate System, and many national and regional mapping systems. It is one of seven projections introduced by Joh ...
United States Government Specifications for the Sectional Aeronautical and VFR Terminal Area Charts
Interagency Air Committee. 11 May 2023. 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 reverse. 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 The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...
and major roads, cities, and bodies of water are shown for visual reference, as well as other identifiable structures (e.g.,
stadium A stadium (: stadiums or stadia) is a place or venue for (mostly) outdoor sports, concerts, or other events and consists of a field or stage completely or partially surrounded by a tiered structure designed to allow spectators to stand or sit ...
s and
water tower A water tower is an elevated structure supporting a water tank constructed at a height sufficient to pressurize a water distribution system, distribution system for potable water, and to provide emergency storage for fire protection. Water towe ...
s). 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 A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...
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 tower Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled a ...
s 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. *
Military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. Militaries are typically authorized and maintained by a sovereign state, with their members identifiable by a d ...
airstrips (without hard-surface runways) are shown with two concentric circles. * Private airports are shown with the letter "R" inside a circle. * A
heliport A heliport is a small airport which has a helipad, suitable for use by helicopters, powered lift, and various types of vertical lift aircraft. Designated heliports typically contain one or more touchdown and liftoff areas and may also hav ...
is designated with "H" in a circle. * An unverified airstrip is shown with a "U" in a circle. * An abandoned airport with paved runways is shown with a circle having an "X" over it.


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. * Part-time tower operation (a star symbol). * FSS, ATIS/AWOS, CTAF indicators * Control tower, ATIS, UNICOM frequencies, as available * Right traffic pattern alert * Special VFR restrictions * Airport surveillance radar presence * Lighting hour, if any * Elevation in feet (typically at center of longest runway) * Length of longest runway in hundreds of feet


Radio aids and communication boxes

* Beacon locations, type, radio frequency, codes, and features are indicated * Each VOR also includes a circular
compass rose A compass rose or compass star, sometimes called a wind rose or rose of the winds, is a polar coordinates, polar diagram displaying the orientation of the cardinal directions (north, east, south, and west) and their points of the compass, inter ...


Airport traffic and airspace information

* Class B, C, D, E airspace is designated by colored lines of various types * Elevations of floor or ceiling of some types of airspace are also indicated * Location, name, and direction of Federal Airways are shown * Special use airspace is shown using specific colors and markings * Military Training Routes * Terminal Radar Service areas * National Security Areas * Mode C areas


Obstructions

Tall towers are especially dangerous and have specific markings according to their height above ground and whether or not lighted. * Up to 1,000 feet above ground, a small, inverted "V" with a dot * Towers 1,000 feet and over: the "V" is elongated. * Groups of towers are shown with multiple symbols * Towers with high-intensity lights are indicated by "lightning bolts" around the tip of the symbol. * The elevation of the top of the obstacle is shown feet and depicted in both height above mean sea level and height above ground in parentheses.


Topographic information

Based upon standard mapping symbols, these markings usually designate man-made structures that may be identifiable from the air, including: * Major roadways, with or without showing route numbers (solid lines) * Railroads, bridges, viaducts, dams (black lines, railroads with cross-hatching) * Power transmission lines (may also be an obstacle in some areas) (solid lines between tower symbols) * Aerial cables (dashed line between black boxes) * Outdoor facilities such as stadiums, schools, golf courses, etc. (black box) * Outdoor theaters, race tracks (funnel shape, oval shape) * Water tank (black dot), lookout towers (circle with triangle inside), oil wells (empty circle), water wells (blue dot) * Coast guard stations (diamond with "CG") 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: *
Isogonic line A contour line (also isoline, isopleth, isoquant or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensi ...
s, dashed magenta lines, indicating magnetic variation for a given year; * Indications of flashing lights (star with Fl) or marine lights (black dot); * Local operations such as parachuting, glider, and ultralight (magenta parachute or glider symbol with letter G, H (hang glider), U (ultralight)); * Preferred reporting points (magenta flag with name), on easily identified features; and * VFR waypoints that are listed in the pertinent Airport/Facility Directory.


References


External links


FAA Aeronautical Charts Products and InformationFAA Aeronautical Chart Users Guide (March 2020)
{{DEFAULTSORT:Aeronautical Chart Conventions (United States) Air navigation Aviation in the United States Aeronautical charts