Definition
A data link system operating on 978 MHz that supports ADS-B Out, ADS-B In, Flight Information Service-Broadcast (FIS-B), and Traffic Information Service-Broadcast (TIS-B). In the United States, UAT is approved for aircraft operating below 18,000 feet MSL and is one of two ADS-B data link options, the other being 1090 MHz Extended Squitter (1090ES).
Plain English
A radio in the aircraft that sends out the airplane's position and receives free weather and traffic information from ground stations. It works on a frequency dedicated to general aviation flying below 18,000 feet.
Context Anchor
Seen in data link weather discussions, especially when describing how an aircraft receives FIS-B weather products on 978 MHz.
Derivation
Universal because it carries several services on one link (position reporting, weather, and traffic). Access reflects that it gives pilots access to information broadcast from the ground network. Transceiver because it both transmits and receives.
Why Pilots Care
It gives pilots free, real-time weather and traffic data directly in the cockpit without ground radar support.
Analogy
Think of UAT as a specific radio lane used for aviation data. If your aircraft has equipment tuned to that lane, it can receive the information being broadcast there.
Intuition Check
UAT is not the weather itself. It is the data link that can carry weather and other aviation information to properly equipped aircraft.
Example Sentence 1
The aircraft is equipped with a UAT, so the pilot receives FIS-B weather products on the cockpit display during the flight.
Example Sentence 2
UAT units also send the aircraft's position so others can see it on their traffic displays.