Cirrus DESIGN SR20 Information Manual page 350

Section 9
Supplements
Section 1 - General
The airplane is equipped with a GARMIN GNC 420 GPS Navigator
with VHF Com herein referred to as the "Navigator." The GNC 420 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.
Provided the GPS Navigator is receiving adequate usable signals, it
has been demonstrated capable of and has been shown to meet the
accuracy specifications of:
VFR/IFR, enroute, terminal, and instrument approach (GPS)
operations, that is, enroute, terminal, and instrument approach
within the U.S. National Airspace System, North Atlantic Minimum
Navigation Performance Specification (MNPS) Airspace using the
WGS-84 (or NAD 83) coordinate reference datum in accordance
with the criteria of AC 20-138, AC 91-49, and AC 120-33.
Navigation data is based upon use of only the global positioning
system (GPS) operated by the United States.
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Figure - 1
GARMIN GNC 420 Front Panel
Cirrus Design
SR20
SR20_FM09_1109
P/N 11934-S23
Revision 02: 08-15-07