Definition
A navigation system that determines an aircraft's position, velocity, and time by receiving and processing radio signals from a constellation of orbiting satellites. The receiver calculates its location by measuring the precise time it takes for signals to arrive from multiple satellites whose positions are known.
Plain English
A way to figure out where the aircraft is by listening to signals from satellites in space. The receiver works out its position by comparing how long the signals took to reach it from several different satellites at once.
Context Anchor
Seen in GPS discussions, flight planning, cockpit navigation displays, and avionics checks before and during flight.
Derivation
Satellite comes from the Latin satelles, meaning attendant or companion — something that travels alongside. In space, satellites travel alongside the Earth in orbit. So a satellite-based navigation system is one whose reference points are these orbiting companions, rather than ground stations.
Why Pilots Care
Satellite-based navigation has largely replaced ground-based systems for en route and approach navigation. Understanding that position is derived from satellites — not from any ground transmitter near the aircraft — explains why coverage is global, why signal integrity monitoring matters, and why GPS outages or interference are a real operational concern.
Intuition Check
Do not think of this as the airplane talking to a satellite like a phone call. The aircraft mainly receives signals from satellites and uses those signals to calculate where it is.
Example Sentence 1
Most modern general aviation aircraft use a satellite-based navigation system as their primary means of position determination.
Example Sentence 2
Many training aircraft now use a satellite-based navigation system for cross-country flights instead of relying only on VORs.