Aeronautical Chart

How Is an Aeronautical Chart Used?

An aeronautical chart is a map used by pilots in navigating an aircraft to determine position, safe altitude, and the best routes, alternate routes in case of emergency, airspace boundaries, radio frequencies, and other navigation aids. Charts are categorized by scale, which is proportionate to the size of the area they depict, with larger areas by necessity having a reduced amount of detail. Different charts, therefore, are used for each phase of a flight. World aeronautical charts (WAC) cover large areas at a scale of 1:1,000,000. Operational navigation charts (ONC) are at the same scale as world aeronautical charts, but because they are designed for use outside of WAC areas, they omit some information like airspace restrictions. Sectional charts at a scale of 1:500,000 cover areas 340 square miles in area. VFR terminal charts cover the vicinity of an airport and are at a scale of 1:250,000.