Definition
A satellite placed in a geostationary orbit approximately 22,236 nautical miles above the equator, where its orbital period matches Earth's rotation so it appears to remain fixed over a single point on the ground. In aviation, GEO satellites are used by the Wide Area Augmentation System (WAAS) to broadcast GPS correction and integrity data to aircraft receivers.
Plain English
A satellite that sits high above the equator and stays parked over the same spot on Earth as the planet turns. WAAS uses these satellites to send GPS correction signals to aircraft.
Context Anchor
Seen in WAAS and NextGen diagrams, especially where the FAA shows how GPS correction information gets from ground stations to aircraft.
Derivation
From 'geo' (Greek 'gē', meaning Earth) and 'stationary' (staying in one place). The satellite is not actually motionless — it orbits at the same rate Earth spins, so from the ground it looks like it never moves.
Why Pilots Care
Provides continuous, stable signal coverage for precise navigation augmentation without the need to switch between moving satellites.
Analogy
A GEO satellite is like a high light on a pole that always shines on the same area. It is actually in motion, but from your point of view it stays in the same place.
Grounding Statement
Picture a satellite hovering over the same spot on the equator all day, every day — that fixed position is what makes it useful for continuously broadcasting correction signals to aircraft below.
Intuition Check
Do not assume a GEO satellite is just another GPS satellite. In this context, it is mainly a broadcast link for WAAS correction and safety information, positioned so it appears to stay over the same part of Earth.
Example Sentence 1
The aircraft's WAAS receiver lost the GEO satellite signal, downgrading the approach from LPV to LNAV minimums.
Example Sentence 2
Pilots using GPS approaches benefit from GEO satellites because the signal does not move across the sky during the flight.