Definition
A free ground-based service that uplinks radar-derived traffic information to aircraft equipped with ADS-B In receivers. Air traffic control radar data on nearby aircraft is transmitted from ground stations so that ADS-B In equipped pilots can see traffic that is not transmitting ADS-B Out themselves.
Plain English
A free service that takes the traffic the controllers can see on radar and beams it up to your cockpit display, so you can see other aircraft nearby — even ones that don't have the newer ADS-B equipment.
Context Anchor
You may see TIS-B discussed with ADS-B traffic displays, cockpit traffic alerts, and the limits of traffic information shown in flight.
Derivation
Broadcast' is the key word here — the service sends traffic data outward to any properly equipped aircraft in range, rather than to one specific user. It complements ADS-B by filling in the picture with traffic seen only by ground radar.
Why Pilots Care
Gives pilots an additional source of traffic awareness beyond visual scanning or onboard TCAS, especially for aircraft without ADS-B Out.
Grounding Statement
TIS-B is ground-sent traffic information that helps fill in traffic your aircraft might not receive directly from other aircraft.
Intuition Check
TIS-B does not mean every aircraft around you is guaranteed to appear on your display. It depends on ground coverage, surveillance sources, aircraft equipment, and the quality of the information being received.
Example Sentence 1
With ADS-B In installed, the pilot received TIS-B traffic on the cockpit display and spotted the converging aircraft well before reaching the practice area.
Example Sentence 2
TIS-B updated the location of a non-ADS-B aircraft that was not visible on the primary ADS-B feed.