Definition
A ground-based air traffic surveillance service that uplinks nearby traffic information to suitably equipped aircraft via the Mode S transponder data link. Using radar returns from terminal area surveillance radars, TIS provides the pilot with the position, altitude, altitude trend, and ground track of other transponder-equipped aircraft within a defined range and altitude band around the user's aircraft, displayed on a compatible cockpit display.
Plain English
A service that takes what ground radar can see of nearby aircraft and sends it up to your cockpit display, so you can see the traffic around you on a screen.
Context Anchor
Seen in instrument flying, cockpit traffic displays, and discussions of equipment that helps pilots spot nearby aircraft.
Why Pilots Care
Helps pilots maintain awareness of nearby traffic and avoid conflicts, especially when visual contact is limited.
Intuition Check
Do not read “Traffic Information Service” as a full traffic-control or collision-avoidance service. Here, “traffic” means nearby aircraft, and the service only provides advisory information about some of them.
Example Sentence 1
With TIS active on the multifunction display, the pilot saw a target one mile ahead, 500 feet below and climbing, and adjusted the descent accordingly.
Example Sentence 2
TIS provided an alert about an aircraft climbing through the same altitude five miles ahead.