Radio Status; Emergency Frequency (121.500 Mhz); Quickly Tuning And Activating 121.500 Mhz; Stuck Microphone - Garmin G1000 Reference Manual

Radio Status

When a COM radio is keyed, a white TX indication
appears to the right of the active COM frequency to indi-
cate that a transmission is in progress. The TX indication
disappears once COM transmission is completed.

Figure 3-9 Radio Status Indications

NOTE: If a signal is transmitted on a COM radio
for which frequency toggling is enabled (i.e., on
which the tuning box is located), the Frequency
Toggle Arrow disappears and is replaced by a
TX indication.

Emergency Frequency (121.500 MHz)

When a COM tuning failure is detected by the system,
the emergency frequency (121.500 MHz) is automatically
loaded into the active frequency field of the COM radio
for which the tuning failure was detected.

Figure 3-10 COM Tuning Failure

NOTE: In the event of a dual display failure,
the emergency frequency (121.500 MHz)
automatically becomes available to the pilot
through the pilot headset.
Garmin G1000 Cockpit Reference Guide for Cessna Nav III

Quickly Tuning and Activating 121.500 MHz

Pressing and holding the COM Frequency Toggle key
for approximately two (2) seconds automatically loads the
emergency COM frequency (121.500 MHz) into the ac-
tive frequency field of the COM radio for which frequency
toggling is enabled.

Figure 3-11 Quickly Tuning 121.500 MHz

Stuck Microphone

If the COM1 (or COM2) push-to-talk (PTT) switch be-
comes stuck, or is accidentally left in the keyed position,
or if a signal continues to be transmitted after the switch
is released, the COM transmitter automatically times out
(i.e., ceases to transmit) after 35 seconds of continuous
transmitting, and an alert appears on the PFD to advise
the crew of a stuck COM microphone (see Figure 3-12).

Figure 3-12 Stuck COM Microphone Alert

SECTION 3 – NAV/COM &
TRANSPONDER
43