MODE S TRANSPONDER SYSTEM
DESCRIPTION
The Mode S transponder system consists of two Mode S transponder units. Only one transponder unit is active at any one
time, while the other has a standby role. The transponder system supplies ATC, or a traffic alert and collision avoidance
system (TCAS) equipped aircraft with aircraft identification and altitude data in response to an interrogation. The transpon-
der used with TCAS is equipped with two paired antennas to transmit and receive interrogations above and below the air-
craft without the signal being masked by the airframe.
The transponder will go into ident mode for approximately 18 seconds when the ID function key is pushed and the annun-
ciator illuminates.
COMPONENTS AND OPERATION
ATC ANTENNAS
Each transponder system has two paired antennas. Each system has an upper and lower antenna located on the forward
fuselage.
TRANSPONDER MODES
ATC/TCAS mode selection is as follows:
- STBY
- TA/RA
- TA ONLY
- ALT ON
- ALT OFF
Selecting STBY on either MFD causes the TCAS to go to standby mode. At system power up on the ground, the system
powers up in standby mode.
TA/RA is the normal TCAS mode. When TA/RA mode is set, the TCAS computer generates intruder traffic symbology
and resolution advisory vertical speed fly to commands. The intruder traffic symbology shows on the PFD and/or MFD
when selected. RA vertical speed fly to commands show on the PFD vertical speed scale when commanded by the TCAS.
RAs are not displayed when TA ONLY is the active mode. This annunciation is displayed in cyan when TA ONLY mode
is selected. This annunciation turns yellow and flashes when a TA is present.
ALT ON mode is used when ATC transponder mode C operation is desired, but TCAS operation is not. The TCAS com-
puter does not show traffic on the displays, does not issue resolution advisories, and the ATC transponder does not reply to
other aircraft TCAS interrogations. Mode C is not reported when interrogated by ATC.
ALT OFF mode is used when TCAS and ATC transponder operation is not desired. The TCAS computer does not show
traffic on the displays, does not issue resolution advisories, and the ATC transponder does not reply to other aircraft TCAS
interrogations. Also, mode C is not reported when interrogated by ATC.
Challenger Global 300 - Navigation
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