Definition
A ground-based surveillance service that uses radar data from terminal Mode S sensors to send nearby traffic information directly to the cockpit of a properly equipped aircraft. The service displays the position, altitude, and movement of other transponder-equipped aircraft within a defined range of the user's aircraft, giving the pilot a picture of surrounding traffic on a cockpit display.
Plain English
A service that uses ground radar to detect other aircraft near you and sends that information up to your cockpit so you can see them on a screen.
Context Anchor
Seen in instrument flying, avionics displays, and traffic-awareness discussions, especially when learning what onboard traffic information can and cannot do.
Derivation
The name describes the service plainly: traffic (other aircraft around you) and information (data sent to you). It is called a service because the FAA provides it from the ground rather than the aircraft generating the data on its own, which distinguishes it from systems like TCAS that work aircraft-to-aircraft.
Why Pilots Care
Gives pilots real-time awareness of nearby traffic, helping avoid mid-air collisions when visual scanning is limited or workload is high.
Intuition Check
Do not read “traffic information service” as a guarantee that all nearby aircraft are shown. It means an advisory aid that provides traffic information when the system can receive and display it.
Example Sentence 1
Flying near a busy terminal area, the pilot used TIS to spot a nearby aircraft on the cockpit display before making visual contact.
Example Sentence 2
TIS showed a target three miles ahead at the same altitude, prompting an altitude change.