Definition
Radio signals transmitted from satellites in orbit that aircraft receivers use to determine position, altitude, time, and velocity. The most common source is the Global Positioning System (GPS), but other satellite constellations also provide navigation signals. Aircraft equipped with appropriate receivers can use these signals for en route navigation, approach guidance, and integration with flight management and autopilot systems.
Plain English
These are navigation signals beamed down from satellites in space. An aircraft receiver picks them up and works out exactly where the aircraft is and where it is going.
Context Anchor
Seen in discussions of satellite navigation equipment and navigation instruments, especially when comparing satellite-based navigation with ground-based navigation aids.
Derivation
Space-based' simply means the signal source is in space (satellites in orbit), as opposed to ground-based navigation aids like VORs or NDBs that transmit from fixed locations on the surface. Knowing this contrast is the whole point of the phrase.
Why Pilots Care
They allow accurate navigation anywhere without ground stations, supporting IFR operations and reducing reliance on older radio aids.
Grounding Statement
Picture several satellites constantly sending timing messages while the aircraft receiver uses those messages to work out the airplane’s location.
Intuition Check
Space-based does not mean the airplane is navigating in outer space. It means the navigation signals come from satellites above Earth instead of from equipment on the ground.
Example Sentence 1
The aircraft's flight management system uses space-based navigation signals to fly the planned route directly between waypoints.
Example Sentence 2
During an IFR approach the pilot monitors space-based navigation signals for lateral and vertical guidance.