Definition
A free data service transmitted on the 978 MHz UAT frequency that delivers weather and aeronautical information to suitably equipped aircraft. FIS-B products include graphical and textual weather (NEXRAD radar imagery, METARs, TAFs, AIRMETs, SIGMETs, PIREPs, winds and temperatures aloft), NOTAMs, TFRs, and special use airspace status. FIS-B is one-way, ground-to-air only, and is available within range of an ADS-B ground station while the aircraft is airborne.
Plain English
FIS-B is a free weather and flight information feed sent up from ground stations to aircraft that can receive it. It gives the pilot things like radar pictures, weather reports, forecasts, and airspace updates in the cockpit, at no charge.
Context Anchor
Seen in ADS-B In equipment, cockpit weather displays, and discussions of traffic and weather information available through ADS-B.
Derivation
The name is descriptive: it 'broadcasts' (sends out one-way) 'flight information services' (weather and aeronautical data). 'Broadcast' here matters — it means the ground station transmits to anyone in range, not a two-way request-and-reply link.
Why Pilots Care
Gives pilots real-time weather and NOTAM information without needing voice radio calls, supporting better flight planning and safety decisions.
Analogy
FIS-B is like a radio station for aviation information: the station sends information out, and your aircraft can receive it if it has the right receiver and is within range.
Intuition Check
Do not assume “broadcast” means the aircraft requested a custom update. Here it means the system sends information out for equipped aircraft to receive.
Example Sentence 1
After takeoff, the FIS-B feed populated the moving map with NEXRAD imagery showing a line of storms north of the route.
Example Sentence 2
FIS-B delivered updated flight information services throughout the cross-country flight.