Section 9
Cirrus Design
Supplements
SR22
GPS Navigator
The GARMIN GNC 420 GPS navigator is the secondary system (GPS
2), is IFR certified, and is coupled to the airplane's CDI. The GARMIN
GNC 420 GPS navigator is capable of providing IFR enroute, terminal,
and approach navigation with position accuracies better than 15
meters. The system utilizes the Global Positioning System (GPS)
satellite network to derive the airplane's position (latitude, longitude,
and altitude) and the altitude digitizer to enhance the altitude
calculation. The GPS 2 antenna is located under the glareshield along
the airplane centerline. All GPS navigator controls and functions are
accessible through the GNC 420 front control panel located in the
center console. The panel includes function keys, power switches,
MSG and Nav status annunciators, color LCD display, two concentric
selector knobs on each panel, and a Jeppesen NavData card slot in
each panel. The GNC 420 navigator is powered by 28 VDC through
the 5-amp GPS2 and 7.5-amp COM 2 circuit breakers on the Avionics
Non-Essential Bus.
The Jeppesen Navigation Database provides access to data on
Airports, Approaches, Standard Instrument Departures (SIDs),
Standard Terminal Arrivals (STARs), VORs, NDBs, Intersections,
Minimum Safe Altitudes, Controlled Airspace Advisories and
Frequencies. North American and International databases are
available. Database information is provided on a card that can be
inserted into the card slot on the GPS unit. Subscription information is
provided in a subscription packet provided with each system.
Communication (COM) Transceiver
The
GNC
420
includes
a
digitally-tuned
integrated
VHF
communications (COM) transceiver. The transceiver and integrated
controls are mounted in the GARMIN GNC 420 unit. The transceiver
receives all narrow- and wide-band VHF communication transmissions
transmitted within a frequency range of 118.000 MHz to 136.975 MHz
in 25.0 kHz steps (720 channels). For European operations, the COM
can be operator configured for 8.33 kHz channel spacing (2280
channels). The tuning controls are located at the left side of the GNC
420 front panel. Frequency tuning is accomplished by rotating the
large and small concentric knobs to select a standby frequency and
then transferring the frequency to the active window. The COM
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P/N 13772-104
Revision 2: 08-15-07
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