Definition
WGS-84 is the global reference system that defines a standard model of the Earth's shape, size, and gravitational field, and provides a uniform coordinate framework (latitude, longitude, and altitude) used for precise navigation. GPS satellites broadcast their positions, and receivers compute aircraft positions, in WGS-84 coordinates.
Plain English
It is the worldwide map reference that GPS uses. Every GPS position you see is measured against this single shared model of the Earth, so a latitude and longitude in one country lines up correctly with the same point anywhere else.
Context Anchor
Seen in GPS, navigation database, waypoint, and instrument procedure discussions when position coordinates must line up with the correct Earth reference.
Derivation
Geodetic comes from the Greek geodaisia, meaning 'division of the Earth' — the science of measuring the Earth's shape and size. The '1984' is simply the year this version of the system was adopted. Knowing this helps explain why WGS-84 is fundamentally a measuring framework for the whole planet, not a chart or a piece of equipment.
Why Pilots Care
It ensures that all GPS positions are consistent worldwide, preventing navigation errors that could occur if different reference systems were used.
Analogy
It is like agreeing that everyone will use the same ruler and the same starting point before measuring a room. Without that agreement, two people could give numbers that look precise but do not point to the same place.
Grounding Statement
WGS-84 is the shared 'map of the Earth' that GPS uses to tell every receiver, anywhere in the world, exactly where it is.
Intuition Check
WGS-84 is not a GPS unit or a satellite signal. It is the Earth reference system that GPS positions are based on.
Example Sentence 1
All waypoints in the GPS navigation database are stored in WGS-84 coordinates.
Example Sentence 2
Pilots verify that their navigation database is aligned with WGS-84 before relying on GPS approaches.