Baro-Corrected Altitude Versus Gsl Altitude; Using Taws-B - Garmin GTN 625 Pilot's Manual

10.3.4

Baro-Corrected Altitude Versus GSL Altitude

Baro-corrected altitude (or indicated altitude) is derived by adjusting the
altimeter setting for local atmospheric conditions. The most accurate baro-
corrected altitude can be achieved by frequently updating the altimeter setting
to the nearest reporting station along the flight path. However, because actual
atmospheric conditions seldom match the standard conditions defined by the
International Standard Atmosphere (ISA) model (where pressure, temperature,
and lapse rates have fixed values), it is common for the baro-corrected altitude
(as read from the altimeter) to differ from the GSL altitude. This variation results
in the aircraft' s true altitude differing from the baro-corrected altitude.
10.3.5

Using TAWS-B

During unit power-up, the terrain/obstacle database versions are displayed.
At the same time, TAWS self-test begins. One of the following aural messages is
generated:
• "TAWS System Test OK" (not given if the aircraft is on the ground)
• "TAWS System Failure"
TAWS information can be displayed on the Map page. Terrain and obstacles
with heights greater than 200 feet Above Ground Level (AGL) are displayed
in yellow and red. The GTN 6XX adjusts colors automatically as the aircraft
altitude changes.
190-01004-03 Rev. F
View
360
Arc
Layers
Flight Plan
Legend
Layers
TAWS Inhibit
Test TAWS
Figure 10-5 TAWS-B Page Functional Diagram
Garmin GTN 625/635/650 Pilot's Guide
Foreword
Getting
Started
Xpdr Ctrl
Com/Nav
FPL
Direct-To
Proc
Wpt Info
Map
Traffic
Terrain
Weather
Nearest
Services/
Music
Utilities
System
Messages
Symbols
Appendix
Index
10-7