Tis Limitations - Garmin 400 Series Pilot's Manual Addendum

Section 1
TIS Operation and Symbology
Garmin is not responsible for Mode S
geographical coverage. Operation of the
ground stations is the responsibility of the
FAA. Refer to the Aeronautical Information
Manual for a Terminal Mode S Radar Site
Map covering the U.S.
NOTE: TIS will be unavailable at low
altitudes in many areas of the U.S., particu-
larly in mountainous regions. Also, when
flying near the "floor" of radar coverage in
a particular area, intruders below the client
aircraft may not be detected by TIS.
2

TIS Limitations

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NOTE: This section on TIS Limitations is not comprehensive. Garmin recommends the user
review the TIS Limitations section of the Aeronautical Information Manual, Section 1-3-5.
TIS is NOT intended to be used as a collision avoidance system and does not relieve the pilot responsibility
to "see and avoid" other aircraft. TIS should not be used for avoidance maneuvers during IMC or other times
when there is no visual contact with the intruder aircraft. TIS is intended only to assist in visual acquisition
of other aircraft in VMC. No recommended avoidance maneuvers are provided for, nor authorized, as a
direct result of a TIS intruder display or TIS advisory.
While TIS is a useful aid to visual traffic avoidance, it has some system limitations that must be fully
understood to ensure proper use. Many of these limitations are inherent in secondary radar surveillance.
In other words, the information provided by TIS will be no better than that provided to ATC. TIS will only
display aircraft with operating transponders installed.
TIS relies on surveillance of the Mode S radar, which is a "secondary surveillance" radar similar to the
ATCRBS. TIS operation may be intermittent during turns or other maneuvering. TIS is dependent on two-
way, "line-of-sight" communications between the aircraft and the Mode S radar. Whenever the structure of
the client aircraft comes between the transponder antenna (usually located on the underside of the aircraft)
and the ground-based radar antenna, the signal may be temporarily interrupted. Other limitations and
anomalies associated with TIS are described in the AIM, Section 1-3-5.