190-00709-00 Rev. A
Garmin G1000 Pilot’s Guide for the Socata TBM 850
4-29
AUDIO PANEL AND CNS
4.4 GTX 33/33D MODE S TRANSPONDERS
The GTX 33 Mode S Transponder and GTX 33D Diversity Mode S Transponder provide Mode A, Mode C, and
Mode S interrogation and reply capabilities. Diversity incorporates antennas mounted on the top and bottom of
the aircraft for dependable operation while maneuvering. Selective addressing or Mode Select (Mode S) capability
includes the following features:
• Level-2 reply data link capability (used to exchange information between aircraft and ATC facilities)
• Surveillance identifier capability
• Flight ID (Flight Identification) reporting – The Mode S Transponder reports aircraft identification as either the
aircraft registration or a unique Flight ID.
• Altitude reporting
• Airborne status determination
• Transponder capability reporting
• Mode S Enhanced Surveillance (EHS) requirements
• Acquisition squitter – Acquisition squitter, or short squitter, is the transponder 24-bit identification address.
The transmission is sent periodically, regardless of the presence of interrogations. The purpose of acquisition
squitter is to enable Mode S ground stations and aircraft equipped with a Traffic Avoidance System (TAS) to
recognize the presence of Mode S-equipped aircraft for selective interrogation.
The Hazard Avoidance Section provides more details on traffic avoidance systems.
TRANSPONDER CONTROLS
Transponder function is displayed on three levels of softkeys on the PFD: Top-level, Mode Selection, and
Code Selection. When the top-level
XPDR
Softkey is selected, the Mode Selection softkeys appear:
XPDR1
,
XPDR2
,
STBY
,
ON
,
ALT
,
VFR
,
CODE
,
IDENT
,
BACK
.
When the
CODE
Softkey is selected, the number softkeys appear:
0
,
1
,
2
,
3
,
4
,
5
,
6
,
7
,
IDENT
,
BKSP
,
BACK
. The digits 8 and 9 are not used for code entry. Selecting the numbered softkeys in sequence enters
the transponder code. If an error is made, selecting the
BKSP
Softkey moves the code selection cursor to the
previous digit. Selecting the
BKSP
Softkey again moves the cursor to the next previous digit.
Selecting the
BACK
Softkey during code selection reverts to the Mode Selection Softkeys. Selecting the
BACK
Softkey during mode selection reverts to the top-level softkeys.
The code can also be entered with the
FMS
Knob on either PFD. Code entry must be completed with either
the softkeys or the
FMS
Knob, but not a combination of both.
Selecting the
IDENT
Softkey while in Mode or Code Selection initiates the ident function and reverts to the
top-level softkeys.
After 45 seconds of transponder control inactivity, the system reverts back to the top-level softkeys.
