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.
Plain English
A radio station on the ground that sends weather and flight information up to aircraft so pilots can see it on their cockpit displays.
Context Anchor
Seen in WAAS and NextGen discussions, especially in diagrams showing how GPS correction information moves from ground equipment to satellites and then to aircraft.
Derivation
‘Uplink’ means a signal sent from the ground up to an aircraft (as opposed to ‘downlink,’ which goes from aircraft down to the ground). The term tells you the direction of information flow.
Why Pilots Care
It gives pilots real-time information without needing everything stored onboard the aircraft.
Intuition Check
Do not think of a ground uplink station as the station that gives instructions directly to the pilot. In this context, it sends correction data up to a satellite for rebroadcast to aircraft.
Example Sentence 1
Once the aircraft climbed above 5,000 feet, it began receiving FIS-B weather from a nearby ground uplink station.
Example Sentence 2
Ground uplink stations transmit traffic advisories that appear on the cockpit display.