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. Using these charts and other tools pilots are able to determine their position, safe altitude, best route to a destination, navigation aids along the way, alternative landing areas in case of an in-flight emergency, and other useful information such as radio frequencies and airspace boundaries. There are charts for all land masses on Earth, and long-distance charts for trans-oceanic travel.
Specific charts are used for each phase of a flight and may vary from a map of a particular airport facility to an overview of the instrument routes covering an entire continent (e.g., global navigation charts), and many types in between.
Charts for visual flight rules (VFR)
Under "visual flight rules", pilots are expected to see and avoid dangers along the way (obstacles, other aircraft, bad weather, etc), and to use pilotage and other means for navigating. VFR charts include a large amount of information describing the local topography, not the least of which is the elevation. Standardized symbols are used for indication of land and water features such as mountains, shorelines and rivers. Roads, towns and other identifiable features may also be shown, in addition to specific aeronautical details.
Visual flight charts are divided into categories, depending upon their scale, which is proportional to the size of the area covered by one map. The amount of detail is necessarily reduced when larger areas are covered with a map having a compact scale.
- World aeronautical charts (WACs) have a scale of 1:1,000,000 and cover relatively large areas. Outside of WAC coverage, operational navigation charts (ONC) may be used, having the same scale as WACs.
- Sectional charts typically cover a few hundred square miles of area (1:500,000).
- VFR Terminal area charts are created with a scale and coverage appropriate for the general vicinity of a large airport (1:250,000). They may depict preferred VFR flight routes within areas of congested airspace.
Charts for instrument flight rules (IFR)
Instrument flight requires the use of artificial aids to navigation, under the control of an air traffic controller, usually based upon a flight plan. The charts used for IFR flights contain an abundance of information regarding locations (waypoints) "fix" according to measurements from electronic beacons of various types, as well as the routes connecting these waypoints. Only limited topographic information is found on IFR charts.
En-route low and high altitude charts are published with a scale that depends upon the density of navigation information required in the vicinity.
Information from IFR charts is often programmed into an flight management system or autopilot system, which may simplify many of the tasks involved in following (or deviating from) a flight plan.
Terminal procedure publications such as Standard Terminal Arrival plates, Standard Instrument Departure plates, and other documentation provide detailed information for arrival, departure and taxiing at each approved airport having instrument capabilities of some sort.
Sources for charts
Aeronautical charts may be purchased at fixed base operators (FBOs), internet supply sources, or catalogs of aeronautical gear. They may also be viewed online from sources such as Skyvector and the FAA.