Installation Instructions

GTN 6XX/7XX AML STC Installation Manual 190-01007-A3
Page 5-26 Rev. 4
5.5.1.9 Main System Configuration Page
Select ‘Main System’ from the GTN Setup page. This page
displays miscellaneous configuration options as described
below.
Air/Ground Threshold
The air/ground threshold is the groundspeed at which the GTN
transitions from a ground state to an airborne state, and vice
versa. To adjust the air/ground threshold, touch the key to the
right and enter a value. This field has a range of 0 to 99 knots
and is set to 30 knots as a default value.
Air/Ground Discrete
The AIR/GROUND discrete is active-low, and can be
configured to interpret if the aircraft is airborne or on the
ground based upon whether the input is grounded or open. If it
is desired for the air/ground state to be airborne when the squat
switch input is grounded, then toggle the AIR/GROUND
discrete key to Active for Airborne. If it is desired for the
air/ground state to be airborne when the squat switch input is
open, then toggle the AIR/GROUND discrete key to Active for Ground. The default configuration is
Active for Airborne.
Refer to Table 5-11.
Table 5-11. Air/Ground Discrete Configurations
AIR/GROUND Discrete Configuration AIR/GROUND input state GTN Air/Ground Status
Configured Active for Ground
Open Airborne
Grounded On-Ground
Configured Active for Airborne
Open On-Ground
Grounded Airborne
GPS Antenna Height Above Ground
This configures the height of the GPS antenna above ground level while the aircraft is sitting on the
ground. Before proceeding, measure the GPS antenna vertical offset (to the nearest tenth of a foot) as
shown in Figure 5-15. Enter the measured value by touching the key and typing the measured value into
the keypad on the display. This field has a range of 0.0 to 99.9 feet.
GPS Antenna
Vertical Offset (ft)
Figure 5-14. Main System
Configuration Page