Plain English Meaning
A radio station on the ground that sends weather and flight information up to aircraft so pilots can see it on their cockpit displays.
Full Definition
A ground-based transmitter site that broadcasts Flight Information Service-Broadcast (FIS-B) data — including weather, NOTAMs, and other advisory products — up to ADS-B In equipped aircraft on the 978 MHz UAT frequency.
Context Anchor
Seen in WAAS and NextGen discussions, especially in diagrams showing how information moves from ground equipment to satellites and then to aircraft.