Aeronautical chart conventions (United States)
Encyclopedia
This article describes the graphic conventions used in Sectional chart
s and Terminal area chart
s 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.
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., stadium
s and water tower
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
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).
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.
Where relevant, a mountain pass and its elevation may be shown with curved lines.
Sectional Chart
In United States aviation, a sectional chart, often called sectional for short, is a type of aeronautical chart designed for navigation under visual flight rules.-Overview:...
s and Terminal area chart
Terminal area chart
In United States and Canadian 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:...
s published for aeronautical navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
under Visual Flight Rules
Visual flight rules
Visual flight rules are a set of regulations which allow a pilot to operate 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 than basic VFR weather minimums, as specified in the rules of the...
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
United States Department of Defense
The United States Department of Defense is the U.S...
and the Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
".
The legend
Legend
A legend is a narrative of human actions that are perceived both by teller and listeners to take place within human history and to possess certain qualities that give the tale verisimilitude...
of an aeronautical chart
Aeronautical chart
An aeronautical chart is a map designed to assist in navigation of aircraft, much as nautical charts do for watercraft, or a roadmap for drivers...
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
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
and major roads, cities, and bodies of water are shown for visual reference, as well as other identifiable structures (e.g., stadium
Stadium
A modern stadium is a place or venue for outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a structure designed to allow spectators to stand or sit and view the event.)Pausanias noted that for about half a century the only event...
s and water tower
Water tower
A water tower or elevated water tower is a large elevated drinking water storage container constructed to hold a water supply at a height sufficient to pressurize a water distribution system....
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
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
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 towerControl tower
A control tower, or more specifically an Air Traffic Control Tower , is the name of the airport building from which the air traffic control unit controls the movement of aircraft on and around the airport. Control towers are also used to control the traffic for other forms of transportation such...
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.
- MilitaryMilitaryA military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...
airstrips (without hard-surface runways) are shown with two concentric circles. - Private airports are shown with the letter "R" inside a circle.
- A heliportHeliportA heliport is a small airport suitable only for use by helicopters. Heliports typically contain one or more helipads and may have limited facilities such as fuel, lighting, a windsock, or even hangars...
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 VORVHF omnidirectional rangeVOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
also includes a circular compass roseCompass roseA compass rose, sometimes called a windrose, is a figure on a compass, map, nautical chart or monument used to display the orientation of the cardinal directions — North, East, South and West - and their intermediate points. It is also the term for the graduated markings found on the traditional...
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 lines, 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
- VFRVisual flight rulesVisual flight rules are a set of regulations which allow a pilot to operate 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 than basic VFR weather minimums, as specified in the rules of the...
waypoints that are listed in the pertinent Airport/Facility Directory.