Cessna 172S Pilot Operating Handbook page 30

-
SECTION 9 SUPPLEMENTS
SUPPLEMENT 2 - FAA APPROVED
3. MODE ANNUNCIATORS - Displays the operating mode of the
transponde r.
4. REPLY INDICATOR (R) - "R" is illuminated momentarily when
the transponder is replying to a valid interrogation and during
the 18 ±2 seconds following the initiation of an Ident.
5. MODE SELECTOR KNOB - Controls application of power and
selects transponder operating mode as follows:
OFF - Turns set off.
SBY - Turns set on for standby power and code selection.
"SBY" is annunciated.
TST - Self-test function. The transmitter is disabled.
display segments will illuminate.
Turns set on and enables transponder to transmit
ON -
Mode A (aircraft identification) reply pulses.
annunciated.
AL T - Turns set on and enables transponder to transmit
either Mode A (aircraft identification) reply pulses and
Mode
automatically by the interrogating signal.
annunciated.
VFR CODE BUTTON (VFR) - Pressing the VFR Button will
6.
cause a pre-programmed Mode A reply code to supersede
whatever Mode A reply code was previously in use.
illumination is controlled by the RADIO L T dimming rheostat
CLEAR BUTTON (CLR) -- Pressing the CLR button will delete
7.
the last Mode A code digit entered.
8. NUMERIC KEYS
The new code will be transmitted after a S-second delay.
Figure Bendix/King KT 76C Transponder with Blind Encoder
1.
S2-6
C (altitude reporting)
- Selects assigned Mode A reply code.
0-7
(Sheet 2 of 2)
CESSNA
MODEL 172S
All
ON is
pulses selected
AL T is
Button
July
8/98
I
I