Garmin G1000:Socata Pilot's Manual page 285

FLIGHT MANAGEMENT
e) Press the ENT Key to designate this altitude constraint value for use in computing vertical guidance. This
altitude value is now displayed as light blue text. Note that altitude values are now filled in for waypoints back
to where the previous altitude value was entered for OPSHN.
Altitude constraint values associated with the Final Approach Fix (FAF) and waypoints beyond the FAF cannot
be designated for vertical guidance. These altitude values are always displayed as white text. Vertical guidance
from the FAF and on to the Missed Approach Point (MAP) is given using the WAAS GPS altitude source, therefore,
the displayed altitude values are for reference only.
Figure 5-126 Vertical Guidance is Active to the FAF
190-00709-00 Rev. A Garmin G1000 Pilot's Guide for the Socata TBM 850 5-133