Definition
WGS 84 is the global standard reference system used to describe positions on Earth. It defines a mathematical model of the Earth's shape (an ellipsoid), a fixed coordinate framework, and a common reference for latitude, longitude, and elevation. GPS and modern aeronautical charts use WGS 84 so that every position fix refers to the same agreed-upon Earth model.
Plain English
It's the worldwide agreement on how to measure where things are on Earth. Because everyone uses the same model, a latitude and longitude in your GPS matches the same spot on a chart anywhere in the world.
Context Anchor
Seen in chart legends, navigation database information, and discussions of GPS-based position data.
Derivation
Geodetic comes from the Greek geodaisia, meaning 'division of the Earth' — the science of measuring the Earth's shape and positions on it. The 1984 in the name marks the year this version of the system was established.
Why Pilots Care
Using WGS 84 ensures GPS-derived positions align exactly with printed and electronic charts, eliminating coordinate mismatch that could lead to navigation errors.
Analogy
Think of WGS 84 like agreeing on one exact ruler for the whole world. If everyone uses the same ruler, the same numbers point to the same place.
Intuition Check
Do not think of WGS 84 as a route, fix, or navigation aid. It is the reference system behind the position numbers used to locate those things.
Example Sentence 1
The chart legend notes that all coordinates are expressed in WGS 84, so the GPS-displayed position will match the printed values.
Example Sentence 2
Before loading the approach, the pilot confirmed the database was set to WGS 84 so the waypoints would match the approach plate.