ABSTRACT
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superseded by a system called automatic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).