|
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.
|