Garmin G500 Pilots Guide - Page 240

Foreword System Sec 1 PFD Sec 2 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. MFD Sec 3 Features Avoidance Hazard Sec 4 Additional Sec 5 & Alerts Annun. Sec 6 Symbols Sec 7 Appendix A Glossary Sec 8 Index Appendix B 5-28 Garmin G500 Pilot's Guide 190-01102-02 Rev. B