chapter  22
Traffic alert and collision avoidance system
Pages 1

Traffic information system (TIS). This uses

the host aircraft’s Mode S transponder (refer to

Chapter 21) to communicate with the ground-

based secondary surveillance radar (SSR)

network. Traffic information can be obtained

within a five-mile radius, 1,200 feet above or

below the host aircraft. This traffic information is

provided on a (near) real-time basis. The

attraction of TIS is that aircraft hardware and

software are minimal since the system ‘feeds’ off

ground station computations. TIS is unavailable

outside of areas covered by SSR and will be

superseded by a system called automatic

dependent surveillance-broadcast (ADS-B).