Installation manual
5-5 Navigation 
Nav Source 
State 
Description 
GPS 
GPS is the active state, and all external 
deviation data being transmitted by the IFD is 
in reference to the active GPS leg. Note that 
if no GPS leg is active or if no GPS lock, the 
nav mode will be displayed in yellow. 
GPS  VLOC 
GPS is the active state, and VLOC is armed. 
If the GPS flight plan contains a VHF-based 
procedure or leg (e.g. localizer final), then the 
nav mode will automatically transition from 
GPS to VLOC when the capture criteria have 
been met. While GPS is active, all external 
deviation data being transmitted by the IFD is 
in reference to the active GPS leg. That 
transitions to VHF deviation data when the 
switch to VLOC is made.  
VLOC 
VLOC is the active state, and all external 
deviation data being transmitted by the IFD is 
in reference to the active VHF-based leg (e.g. 
Inbound VOR course, localizer deviation, 
etc). Note that if no VHF data is being 
received (e.g. out of range, improperly tuned 
nav radio, etc), the nav mode will be 
displayed in yellow. 
OBS 
OBS becomes the active state and deviation 
data being transmitted by the IFD is reactive 
to the external course setting knob (or the 
Nav Source knob if no external course control 
is present) for the inbound/outbound course. 
Note that this state is accessed by pushing in 
the Nav Source knob, and then it takes the 
place of pure GPS mode as described earlier 
in this table. 










