Appendix F: General Tis Information; Tis Vs. Tas/Tcas; Tis Limitations - Garmin aera 796 Pilot's Manual

APPENDIX F: GENERAL TIS INFORMATION

NOTE: Aircraft without an operational transponder are invisible to TIS.
NOTE: TIS is not intended to be used as a collision avoidance system and does
not relieve the pilot of the responsibility to "see and avoid" other aircraft. TIS
should not be used for avoidance maneuvers during instrument meteorological
conditions (IMC) or when there is no visual contact with the intruder aircraft.
The Traffic Information Service (TIS) provides traffic advisory information to non-
TAS/TCAS-equipped aircraft. TIS is a ground-based service providing the relative
locations of all ATCRBS (Air Traffic Control Radar Beacon System) Mode-A and Mode-C
transponder equipped aircraft within a specified service volume. The TIS ground
sensor uses real-time track reports to generate traffic notification. The aera 795/796
displays TIS traffic information on the Navigation Map. Surveillance data includes all
transponder-equipped aircraft within the coverage volume. The aera 795/796 displays
up to eight traffic targets within a 7.5-nm radius, from 3,000 feet below, to 3,500 feet
above the requesting aircraft.

TIS VS. TAS/TCAS

The main difference between the Traffic Information System (TIS) and Traffic Advisory
(TAS) or Traffic Collision Avoidance Systems (TCAS) is the source of surveillance
data. TAS/TCAS uses an airborne interrogator with a half-second update rate, while
TIS utilizes the terminal Mode-S ground interrogator and accompanying data link to
provide a five-second update rate. TIS and TAS/TCAS have similar ranges.

TIS LIMITATIONS

TIS 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 is neither better
nor more accurate than the information used by ATC. TIS is intended only to assist in
visual acquisition of other aircraft in visual meteorological conditions (VMC). While
TIS 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 intruder display or TIS advisory.
190-01194-00 Rev. A Garmin aera 795/796 Pilot's Guide
Appendix F
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