Sectional aeronautical charts are designed for visual navigation of slow to medium speed aircraft. The topographic information featured consists of the relief and a judicious selection of visual checkpoints used for flight under visual flight rules. The checkpoints include populated places, drainage patterns, roads, railroads, and other distinctive landmarks. The aeronautical information on Sectional Charts includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data. (Scale 1 inch = 6.86 nm/1:500,000. 60 x 20 inches folded to 5 x 10 inches.) Revised semi-annually, except most Alaskan charts are revised annually.