Definition
A free, ground-based broadcast service transmitted on the 978 MHz UAT (Universal Access Transceiver) datalink that delivers weather and aeronautical information to suitably equipped aircraft below approximately 24,000 feet MSL. FIS-B products include METARs, TAFs, NEXRAD radar imagery (regional and CONUS), AIRMETs, SIGMETs, PIREPs, winds and temperatures aloft, NOTAMs, TFRs, and special use airspace status. The service is one-way (ground-to-air), advisory only, and is intended to supplement — not replace — official preflight and in-flight weather briefings.
Plain English
A free in-flight weather and information service that the FAA broadcasts up to your airplane through a small receiver, giving you things like radar pictures, weather reports, and notices while you fly.
Context Anchor
Pilots encounter FIS-B when using cockpit weather displays, portable receivers, or panel equipment that receive ADS-B In weather information during flight.
Derivation
Broadcast' captures the key idea: the FAA transmits this data outward to any aircraft listening, rather than sending it specifically to you. There is no request, no subscription, and no two-way exchange — you simply receive what is being sent.
Why Pilots Care
Gives pilots continuous access to current weather without voice radio calls or ground station contact.
Analogy
FIS-B works a little like a radio station for flight information: if your aircraft has the right receiver and is in range, it can pick up the broadcast.
Grounding Statement
Picture ground stations sending weather and flight notices up to your cockpit display as you fly within their coverage area.
Intuition Check
FIS-B is not a two-way conversation and it is not instant storm detection. It is a one-way broadcast of weather and flight information that may have some delay.
Example Sentence 1
Cruising at 8,000 feet, the pilot checked FIS-B on the tablet and saw a line of precipitation building along the route ahead.
Example Sentence 2
FIS-B delivered updated METARs and TAFs directly to the cockpit display.