Garmin G3X Touch Pilot's Manual page 359

Pressing the NAV Key or touching NAV on the G3X Touch selects Navigation Mode.
Navigation Mode acquires and tracks the selected navigation source (GPS, VOR, LOC).
The flight director follows GPS roll steering commands when GPS is the selected
navigation source. When the navigation source is VOR or LOC, the flight director
creates roll steering commands from the Selected Course and deviation. Navigation
Mode can also be used to fly non-precision GPS and LOC approaches where vertical
guidance is not required.
Backcourse Navigation Mode is selected when the localizer front course is greater
than 105° from the aircraft heading. Backcourse Navigation Mode captures and tracks
a localizer signal in the backcourse direction. The annunciation 'BC' in the Autopilot
Status Box indicates Backcourse Navigation Mode.
If the Course Deviation Indicator (CDI) shows greater than one dot when the NAV
Key is pressed or NAV is touched, the selected mode is armed. If the CDI is less than
one dot, Navigation Mode is automatically captured when the NAV Key is pressed or
NAV is touched. The armed annunciation appears in white to the left of the active
roll mode.
When the CDI has automatically switched from GPS to LOC during a LOC/ILS
approach, GPS Navigation Mode remains active, providing GPS steering guidance until
the localizer signal is captured. LOC Navigation Mode is armed when the automatic
navigation source switch takes place. If the APR Key is pressed or NAV is touched
prior to the automatic navigation source switch, LOC Navigation Mode is armed.
If Navigation Mode is active and either of the following occur, the flight director
reverts to Roll Hold Mode (wings rolled level):
• Different VOR tuned while in VOR Navigation Mode (VOR Navigation Mode reverts
to armed)
• Navigation source manually switched
• During a LOC/ILS approach, the FAF is crossed while in GPS Navigation Mode
after the automatic navigation source switch from GPS to LOC
190-01754-00 Rev. L
Navigation Mode Annunciation
Garmin G3X Touch Pilot's Guide
AFCS
339