Section 1 - General; Models Covered - Garmin 400W-Series Operating Handbook

Section 9
Supplements

Section 1 - General

The WAAS-enabled, Garmin 400W-Series GPS Navigator is capable
of providing primary navigation information for enroute, terminal, non-
precision, and precision approaches with typical position accuracies of
1 meter horizontally and 2 meters vertically.
The Wide Area Augmentation System (WAAS) consists of ground
reference stations positioned across the United States that monitor
GPS satellite data. Two master stations, located on either coast,
collect data from the reference stations and create a GPS correction
message. This correction accounts for GPS satellite orbit and clock
drift plus signal delays caused by the atmosphere and ionosphere.
The corrected data is then broadcast through geostationary satellites.
WAAS also provides the capability of quickly determining when signals
from a given satellite are wrong and removing that satellite from the
navigation solution using Receiver Autonomous Integrity Monitoring
(RAIM), a technology developed to assess the integrity of GPS
signals.
WAAS satellite coverage is only available in North America.
User in other parts of the world can receive WAAS data,
however, the signal has not been corrected and thus does not
improve the accuracy of your receiver.

Models Covered

Two Garmin 400W-Series GPS Navigators are covered in this
publication; the GNC 420W and GNS 430W. Generally, both models
will be referred to as the Navigator, except where there are physical or
operational differences.
For detailed descriptions and full operation instructions for the
GNC 420W or GNS 430W Navigators, refer to the Garmin
400W-Series GPS Navigator Pilot's Guide and Reference, P/N
190-00356-00, Revision A or later revision.
2 of 10
• Note •
• Note •
Cirrus Design
SR20
P/N 11934-S38
Revision 02: 10-29-13