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Part Five
Terrain Proximity
Part Five:
Terrain Proximity Interface
NOTE
: Either the TERRAIN, TAWS (500W-series only),
HTAWS, or Terrain Proximity functionality will be available
via the Terrain page, depending on the installed hardware
and configuration. .
Introduction
Garmin Terrain Proximity is an optional non-TSO-
certified terrain awareness feature of the 400W/500W
series available in helicopter configurations to increase
situational awareness and help reduce controlled flight
into terrain (CFIT). Terrain Proximity is available in
the Nav page group Terrain pages. Terrain Proximity
depicts nearby terrain and obstacles relative to the air-
craft altitude, however it does not provide any alerts.
Terrain Proximity uses information provided from
the GPS receiver to provide a horizontal position and
altitude. GPS altitude is derived from satellite measure-
ments. GPS altitude is converted to a Mean Sea Level
(MSL)-based altitude (GPS-MSL altitude) and is used
to provide terrain coloring that depicts terrain eleva-
tion relative to the aircraft. GPS-MSL altitude accuracy
is affected by factors such as satellite geometry, but it is
not subject to variations in pressure and temperature
that normally affect pressure altitude devices. GPS-MSL
altitude does not require local altimeter settings to
determine MSL altitude.
Terrain Proximity utilizes terrain and obstacle
databases that are referenced to mean sea level (MSL).
Using the GPS position and GPS-MSL altitude, Terrain
Proximity displays a 2-D picture of the surrounding
terrain and obstacles relative to the position and alti-
tude of the aircraft. In this manner, Terrain Proximity
increases awareness of the aircraft proximity to terrain
and obstacles.
Terrain Proximity requires the following to operate
properly:
• The system must have a valid 3-D GPS position
solution.
• The system must have a valid terrain database.
Displaying Terrain Proximity
The Terrain Proximity page is in the Map page group.
1. Turn the
large right
knob to the Map func-
tion.
2. Then, the
small right
knob to the Terrain
Proximity page.
Terrain Proximity Page
190-00356-30 Rev H
