AIM 8/15/19  b. Requirements. Typically, this will be within 55 NM of the sites depicted in FIG 4 − 5 − 5, Terminal Mode S Radar Sites. ATC communication is not a requirement to receive TIS, although it may be required by the particular airspace or flight operations in which TIS is being used. 1. In order to use TIS, the client and any intruder aircraft must be equipped with the appropriate cockpit equipment and fly within the radar coverage of a Mode S radar capable of providing TIS. FIG 4 − 5 − 4 TIS Proximity Coverage Volume FIG 4 − 5 − 5 Terminal Mode S Radar Sites 4 − 5 − 9 Surveillance Systems