Definition
The radio frequency used by the Universal Access Transceiver (UAT) data link in the United States, primarily for ADS-B equipage in aircraft operating below 18,000 feet MSL. Aircraft using 978 MHz UAT can both transmit ADS-B Out position data and receive ADS-B In services, including Flight Information Service-Broadcast (FIS-B) weather and Traffic Information Service-Broadcast (TIS-B) traffic.
Plain English
A specific radio channel set aside by the FAA for sending and receiving ADS-B traffic and weather information in light aircraft flying at lower altitudes.
Context Anchor
Seen in discussions of data link weather, ADS-B equipment, and cockpit displays that receive broadcast weather information.
Derivation
MHz means megahertz. Mega means one million, and hertz is the unit for frequency, named after Heinrich Hertz, an early radio-wave scientist. So 978 MHz means 978 million radio-wave cycles per second.
Why Pilots Care
It gives pilots access to graphical weather and traffic updates in the cockpit without voice radio calls.
Analogy
Think of 978 MHz like a specific radio station. If your receiver is built to tune that station, you can receive the information being broadcast on it.
Intuition Check
978 MHz is not the weather product itself. It is the radio frequency used to carry certain aviation weather and data broadcasts.
Example Sentence 1
The aircraft's 978 MHz UAT receiver displayed current radar imagery and METARs on the cockpit tablet during the cross-country flight.
Example Sentence 2
When flying in areas with good coverage, the 978 MHz signal provides continuous traffic and weather data.