Definition
In GPS, the complete set of satellites operating together as a single navigation system, arranged in specific orbital planes so that enough satellites are visible from any point on Earth to compute a position fix.
Plain English
The full group of GPS satellites circling the Earth. They are spaced so that, no matter where you are, several are always overhead and usable.
Context Anchor
Seen in instrument flying discussions about how GPS receivers get enough satellite signals to determine an aircraft’s position.
Derivation
From the Latin 'com-' (together) and 'stella' (star). Originally it described a group of stars seen as a pattern in the sky. GPS borrows the word because the satellites, taken together, form a coordinated 'pattern' around the Earth.
Why Pilots Care
The number and placement of satellites in the constellation directly affect how many are visible from your location and therefore the accuracy and reliability of GPS navigation.
Grounding Statement
A full GPS constellation keeps at least four satellites visible from almost any point on Earth so a three-dimensional position can be calculated.
Intuition Check
Constellation does not mean a pattern of stars here. In this context, it means a working group of GPS satellites in orbit.
Example Sentence 1
The GPS constellation provides worldwide coverage, so pilots can get a position fix anywhere along the route.
Example Sentence 2
Maintenance on one satellite in the constellation rarely affects coverage because others remain visible from most locations.