Autopilot Operation With The Gdu 620 Emulating Gpss - Garmin G600 Pilot's Manual

5.6.3.2

Autopilot Operation with the GDU 620 Emulating GPSS

NOTE: The GDU 620 has the ability to emulate GPSS roll steering for
autopilots that do not support GPSS. The GDU 620 emulates GPSS by
sending headings to the autopilot that guide turn anticipation.
Many autopilots do not have a GPSS mode. GPSS utilizes roll command
signals calculated by the GPS navigator and sent to the autopilot in order to
allow the aircraft to anticipate turns, make smooth transitions when passing
waypoints, and fly leg types, such as Procedure Turns and Course Reversals.
In order for GPSS to function correctly, the autopilot must have the capability
of interpreting the roll commands. In order to provide GPSS functionality for
autopilots that do not support roll commands, the GDU 620 has the capability
to emulate GPSS commands by continually changing the selected heading data
sent to the autopilot.
GPSS emulation functionality in the GDU 620 is controlled by an optional
external Autopilot Heading Datum switch. When GPSS emulation is active on
the GDU 620, the HSI heading bug does not control the autopilot. Instead, the
GDU 620 processes heading information and sends it to the autopilot to emulate
what GPSS would normally do. The GPSS/Heading bug inactive annunciation
in the lower left corner of the PFD reminds the pilot that the heading bug is not
controlling the autopilot.
1) Select GPS navigation on the HSI.
2) Set the HSI to the desired course (if in OBS mode).
3) Set the optionally installed Autopilot Heading Datum switch to GPSS.
Heading Bug Inactive Indication
4) Engage your autopilot in Heading mode.
190-00601-02 Rev. B
Figure 5-22 GPSS Emulation Indication
Garmin G600 Pilot's Guide
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