Garmin GTN 625 Pilot's Manual page 151

6.14 Points to Remember for Localizer or
VOR-based Approaches
• The default factory setting allows the CDI output to automatically switch
from the GPS receiver to the LOC receiver. This may be changed to manual
in some installations. If the "ILS CDI Selection" setting is changed to
"Manual", you must determine when to select "GPS" or "VLOC" guidance
during the approach. Remember, "VLOC" is required for the final course
segment from the Final Approach Fix (FAF) to the MAP.
NOTE: Installations with certain autopilots, such as the KAP 140 and
KFC225, do not allow automatic ILS CDI switching.
NOTE: GPS phase of flight annunciations (LPV, ENR, etc.) are not applicable
to the external CDI (or HSI) when VLOC is active.
• If the CDI output has not automatically switched from GPS to ILS upon
reaching the FAF, you must manually switch to the VLOC receiver by
touching the CDI key. Verify that "VLOC" is displayed.
• Automatic switching of CDI output is available for ILS, localizer, SDF and
LDA approaches. Automatic CDI switching is not available for backcourse
approaches or VOR approaches.
• When flying an approach with the autopilot-coupled, you must monitor
system functions at all times and verify that the autopilot and external CDI
(or HSI) switch to the VLOC receiver with sufficient time to capture and
track the approach course. Switching to "VLOC" late in the approach may
not provide the autopilot enough time to respond and intercept the approach
course prior to the FAF (depending upon the performance characteristics of
your autopilot and aircraft).
• When an ILS or VOR approach is first selected or executed, the frequency
is automatically checked. If the frequency is incorrect, you will receive a
message and you must place the correct ILS or VLOC frequency in the
active frequency field.
• When flying a localizer-based approach (other than backcourse) with
automatic CDI switching enabled:
190-01004-03 Rev. K Garmin GTN 625/635/650 Pilot's Guide
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6-21