Definition
World Aeronautical Charts (WACs) are aeronautical charts produced at a scale of 1:1,000,000 (1 inch on the chart equals about 13.7 nautical miles) that cover large areas of the Earth's surface in a standard format. They depict cities, towns, principal roads, railroads, distinctive landmarks, terrain relief, and aeronautical information including visual and radio aids to navigation, airports, airways, restricted areas, and obstructions. WACs are designed for navigation by pilots of moderate-speed aircraft and aircraft operating at high altitudes, where the smaller scale is practical. Note: As of 2021, the FAA discontinued production of WACs covering the conterminous United States, Hawaii, Puerto Rico, and the Virgin Islands; pilots in these areas now use Sectional Charts or other replacements.
Plain English
WACs are large-area aviation maps drawn at a smaller scale than Sectionals, so each chart covers more ground but shows less fine detail. They were designed for faster, higher-flying aircraft that cross long distances quickly and don't need the close-in detail a slower aircraft would.
Context Anchor
Seen when choosing charts for cross-country flight planning and when studying FAA chart types.
Derivation
"Aeronautical" comes from the Greek aer (air) and nautikos (relating to sailing/navigation) -- literally "air navigation." "World" reflects that these charts were produced in a standard format covering large portions of the globe, not just one country.
Why Pilots Care
They give pilots the broad picture needed to plan and follow safe routes over hundreds of miles without instrument references.
Analogy
It is like using a road map of an entire country instead of a street map of one town. The country map helps you plan the overall trip, but it will not show every small road.
Intuition Check
Do not assume “world” means one chart of the whole earth. Here it means a wide-area aviation chart series with a large map scale.
Example Sentence 1
For a long cross-country in a faster aircraft, a pilot might historically have chosen a World Aeronautical Chart over a Sectional to reduce the number of charts needed in the cockpit.
Example Sentence 2
Before departure she checked the world aeronautical charts for any special-use airspace along the planned path.