Garmin G1000 NXi Pilot’s Guide for the Cessna NAV III
190-02177-02 Rev. A
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FLIGHT
INSTRUMENTS
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AUDIO P
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HAZARD
AV
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AFCS
ADDITIONAL FEA
TURES
APPENDICES
INDEX
350
HAZARD AVOIDANCE
The optional Garmin GTX 33 ES transponder provides ADS-B Out functions using the 1090 ES data link, and
no ADS-B In traffic display is provided.
The optional Garmin GTX 345R transponder provides ADS-B Out functions using the 1090 ES data link. It
also performs ADS-B In functions using the UAT data link. For the GTX 345, this includes the reception of
Flight Information Services-Broadcast (FIS-B) data link weather service, provided when the aircraft is receiving
data from a participating ground station; refer to the Data Link Weather section for more information about
FIS-B Weather.
AUTOMATIC DEPENDENT SURVEILLANCE-REBROADCAST (ADS-R)
Because it is not required that ADS-B In capable aircraft be able to receive ADS-B data on both the 1090
MHz and 978 MHz data links, a method exists to get data from one data link to the other. ADS-R is the
rebroadcast of ADS-B data by FAA ground stations, which provide this service by taking traffic data from one
link and rebroadcasting it on the other. For example, if two aircraft are in the service volume for a ground
station, and one is transmitting on 1090 MHz and the other is transmitting on 978 MHz, the ground station
retransmits the data from each aircraft on the other link to ensure the two aircraft can “see” each other as
traffic.
For example, if another aircraft can only receive 978 MHz UAT information, it cannot directly ‘see’ another
aircraft sending only 1090 ES information aircraft unless an ADS-R ground station in the vicinity rebroadcasts
the 1090 ES data over the 978 MHz UAT frequency. This is also true for an aircraft when can only receive
1090 ES data; it would need an ADS-R ground station to ‘see’ another aircraft operating on the UAT frequency.
TRAFFIC INFORMATION SERVICE-BROADCAST (TIS-B)
TIS-B provides a link between the secondary surveillance radar (SSR)-based system ATC uses and the ADS-
B-based system. When an ADS-B In or Out capable aircraft is within the service volume of an FAA ADS-B
ground station, the ground station broadcasts a portion of the ATC radar data to the aircraft. This aircraft is
then included in the list of aircraft being provided TIS-B service and is then considered a “TIS-B participant.”
TIS-B coverage is available when the aircraft is within ground station coverage, in SSR coverage, and the
other aircraft is also in SSR coverage, and is transmitting its altitude.
The ground station provides ATC radar information for other aircraft within ±3,500 feet and 15 NM of the
participant, to include altitude, position, ground speed, and ground track. TIS-B broadcasts occur once every
three to thirteen seconds, depending on the characteristics of the ground station providing the TIS-B service.
ADS-B WITH TAS
When the system is receiving ADS-B In traffic and with a TAS in Operating Mode, the system attempts to
match (or “correlate”) data the two traffic sources. When a correlation is made, the system displays the traffic
information for the tracked aircraft determined to be the most accurate. Any traffic that is not correlated
(i.e., only detected by one system but not the other) is also displayed for the flight crew. This may occur,
for example, if another aircraft is beyond the surveillance range of the TAS, but own aircraft is receiving
information via ADS-B for the other aircraft. The traffic correlation feature improves the accuracy of the traffic
displayed, while reducing the occurrence of displaying the same traffic for a given aircraft twice.
NOTE:
When operating on the edges of ATC radar coverage or when using an optional active traffic system
providing intermittent traffic data, a single aircraft may be briefly or periodically be depicted as two aircraft
on the display.
