Tis-A Limitations - Garmin Aera 760 Pilot's Manual

Appendix F

TIS-A LIMITATIONS

TIS-A relies on surveillance of the Mode-S radar system, which is a "secondary
surveillance" radar system similar to that used by ATCRBS. Many limitations are
inherent in secondary radar surveillance. Information provided by TIS-A is neither
better nor more accurate than the information used by ATC. TIS-A is intended only to
assist 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 be
considered 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 aircraft
and the Mode-S radar antenna. Whenever the structure of the aircraft comes
between the transponder antenna and the ground-based radar antenna, the signal
may be temporarily interrupted.
NOTE:
Refer to the TIS-A Limitations section of the Aeronautical Information
Manual (AIM) for a more comprehensive explanation of limitations and anomalies
associated with TIS-A.
NOTE:
TIS-A is unavailable at low altitudes in many areas of the United States. This
is often the case in mountainous regions.
NOTE:
Garmin is not responsible for Mode S geographical coverage. Operation of
the ground stations is the responsibility of the FAA. Refer to the AIM for a Terminal
Mode S radar site map.
212
Garmin aera 760 Pilot's Guide 190-02674-00 Rev. B