Garmin GFC 600 Pilot's Manual page 46

AFCS
WARNING:
with the autopilot coupled, the aircraft will not level off at the MDA even if
the MDA is set in the altitude preselect.
Once the following conditions have been met, the glidepath can be captured:
• GPS must be the active lateral mode.
• Vertical deviation is valid.
• The CDI is at less than full-scale deviation
• Automatic sequencing of waypoints has not been suspended (no 'SUSP'
annunciation on the HSI)
Pressing the CWS button while Glidepath mode is active does not
NOTE:
cancel the mode. Upon release of the CWS button the autopilot will guide
the aircraft back to the glidepath.
GMC 605 AND GI 285 ANNUNCIATIONS
The GMC 605 and GI 285 annunciate 'GP' for Glidepath mode. Since Glidepath
mode relies on GPS positioning, the 'GPS' lateral mode is also annunciated.
38
When flying an LNAV approach (with vertical descent angle)
GMC 605 Annunciating Glidepath Mode
GI 285 Annunciating Glidepath Mode
Garmin GFC 600 Pilot's Guide 190-01488-00 Rev. B