User Guide

Series III Avionics
Pilot's Guide
Page 25
Operating the TRS-42A
Preflight
1. Set the FUNCTION SELECTOR to TST.
2. Select System 1 or System 2 (if more than one transponder system is installed).
3. Note the encoding barometric altitude in lower display.
4. Press the IDENT pushbutton. Note that the numbers 8888 are present in upper line of the display,
and that 88888 is displayed in lower line.
5. Set the FUNCTION SELECTOR to SBY. The system is now ready for operation.
Flight Operation
1. Use the CODE SELECT knobs to set the requested ATC transponder code into the display.
– OR –
If the flight is VFR and 1200 with altitude reporting is the appropriate code and mode, set the
FUNCTION SELECTOR to VFR.
2. For non-altitude reporting mode, set the FUNCTION SELECTOR to ON.
3. For altitude reporting mode, set the FUNCTION SELECTOR to ALT.
4. If ATC requests "stop altitude squawk", set the FUNCTION SELECTOR to ON.
5. If ATC requests "squawk standby," set the FUNCTION SELECTOR to SBY.
The TRS-42A is programmed to automatically select code 1200 when the FUNCTION SELECTOR is set
to VFR. To program another code for the VFR position, perform the following steps:
1. Set the FUNCTION SELECTOR to SBY position.
2. Press and release the IDENT pushbutton.
3. Select the new code with the CODE SELECT knobs.
4. Press and release the IDENT pushbutton again.
These steps enter the newly selected VFR code into TRS-42A system memory. The new code is in
effect any time the FUNCTION SELECTOR is in the VFR position.