plane chart

A navigation chart is a map specifically designed for navigation. Early charts, developed in the Mediterranean around the 13th century, were "plane charts." These depicted small areas of the Earth's surface as a flat plane, with latitude and longitude lines appearing as straight, perpendicular grids. They also featured rhumb lines (loxodromes) to indicate wind direction.

Plane charts did not account for the Earth's curvature and were therefore unsuitable for high-latitude navigation. By the 17th century, they were largely replaced by Mercator projection charts, which represent compass directions as straight lines and are more accurate for long-distance sea travel. Aeronautical charts, used for air navigation, are similar but emphasize features relevant to aviation, such as topography and airports.12