Garmin aera 660 Pilot’s Guide 190-02017-20 Rev. AAppendix F152OverviewNavigationFlight PlanningHazard AvoidanceAdditional FeaturesAppendicesIndexTIS-A LIMITATIONSTIS-A relies on surveillance of the Mode-S radar system, which is a “secondarysurveillance” radar system similar to that used by ATCRBS. Many limitations areinherent in secondary radar surveillance. Information provided by TIS-A is neitherbetter nor more accurate than the information used by ATC. TIS-A is intended only toassist in visual acquisition of other aircraft in visual meteorological conditions (VMC).While TIS-A is a useful aid for visual traffic avoidance, system limitations must beconsidered to ensure proper use. No recommended avoidance maneuvers are given,nor authorized, as a direct result of a TIS-A intruder display or TIS-A advisory.• TIS-A operation may be intermittent during turns or other maneuvering.• TIS-A is dependent on two-way, line-of-sight communications between the aircraftand the Mode-S radar antenna. Whenever the structure of the aircraft comesbetween the transponder antenna and the ground-based radar antenna, the signalmay be temporarily interrupted.NOTE:Refer to the TIS-A Limitations section of the Aeronautical InformationManual (AIM) for a more comprehensive explanation of limitations and anomaliesassociated with TIS-A.NOTE:TIS-A is unavailable at low altitudes in many areas of the United States. Thisis often the case in mountainous regions.NOTE:Garmin is not responsible for Mode S geographical coverage. Operation ofthe ground stations is the responsibility of the FAA. Refer to the AIM for a TerminalMode S radar site map.
