Field Guide · protocol

Also known as: FIS-B, Flight Information Service-Broadcast

FIS-B (Flight Information Service–Broadcast) is a free ground-to-air uplink, carried on the UAT 978 MHz link, that broadcasts graphical and textual weather and aeronautical information — radar mosaics, METARs, TAFs, NOTAMs, and airspace notices — to any aircraft with an ADS-B In receiver.1 It is the weather counterpart to the traffic service TIS-B, and the pair are the FAA’s incentive for equipping with UAT.

ground station NEXRAD METAR/TAF NOTAM/TFR 978 MHz FIS-B uplink cockpit display no subscription · US NAS
FIS-B broadcasts layered weather and notice products (NEXRAD, METAR/TAF, NOTAM/TFR) on 978 MHz to any listening cockpit.

Overview

FIS-B turns the ground-uplink half of each UAT frame into a rolling weather broadcast. Because it is a broadcast, one transmission serves every aircraft in a station’s coverage, and there is no request/response and no per-user cost. Products are transmitted on a cycle, with time-critical items (NEXRAD regional radar, special-use airspace) repeated frequently and slowly changing bulk products less often.

Technical characteristics

Property Value
Direction Ground-to-air (broadcast)
Frequency 978 MHz (UAT link only)
Carrier products NEXRAD (regional + CONUS), METAR, TAF, PIREP, winds/temps aloft
Notices NOTAM, TFR, SUA status, AIRMET/SIGMET
Transport UAT ground-uplink segments, Reed–Solomon coded
Update cadence Product-dependent (minutes)
Standard RTCA DO-358

Each product is segmented into UAT ground frames, protected by a Reed–Solomon code, and reassembled by the receiver. NEXRAD imagery is delivered as a coarse national mosaic plus a finer regional block around the aircraft, trading resolution against the limited link bandwidth.

History

FIS-B was specified by the FAA to accompany the UAT rollout, with the message and product set standardised in RTCA DO-358. It replaced earlier subscription-based satellite weather services for many general-aviation pilots by making a broad product set free at the point of use.

Deployment

FIS-B is a U.S.-only service tied to the 978 MHz UAT infrastructure; it is not available on the worldwide 1090 MHz link. Pilots receive it through portable or panel ADS-B In units, typically alongside TIS-B traffic. Because products are broadcast on a cycle and can be several minutes old, FIS-B weather is advisory — suitable for strategic planning, not tactical thunderstorm penetration.

Decoding it with GopherTrunk

Not decoded. FIS-B lives entirely on the UAT 978 MHz link, which GopherTrunk does not tune or demodulate — GopherTrunk’s aviation decoding is limited to 1090 MHz ADS-B. FIS-B is receivable with a wideband SDR and open UAT decoders, but reconstructing its weather products is outside GopherTrunk’s scope. See UAT (978 MHz) for the underlying link.

Sources

  1. Flight Information Services-Broadcast — Wikipedia, for the FIS-B free weather/aeronautical uplink, its NEXRAD/METAR/TAF/NOTAM product set, and delivery on the 978 MHz UAT ground-uplink link. ↩

See also