Garmin G600 manual GDC 74A/74B, 4 GRS

	Foreword
Sec 1	System
Sec 2	PFD
Sec 3	MFD

1.1.3GDC 74A/74B

The GDC 74A/74B Air Data Computer (ADC) compiles information from the pitot/static system and an Outside Air Temperature (OAT) sensor. The GDC 74A/74B provides pressure altitude, airspeed, vertical speed, and OAT information to the G600 system. The GDC 74A/74B communicates with the GDU 620 and GRS 77 using an ARINC 429 digital interface.

Figure 1-4 GDC 74A/74B Air Data Computer

Sec 4	Hazard	Avoidance
Sec 5	Additional	Features
Sec 6	Annun. & Alerts
	Sec 7	Symbols
	Sec 8	Glossary

1.1.4GRS 77

The GRS 77 is an Attitude and Heading Reference System (AHRS) unit that provides aircraft attitude information to the G600 display. The unit contains advanced tilt sensors, accelerometers, and rate sensors. In addition, the GRS 77 interfaces with both the GDC 74A/74B Air Data Computer and the GMU 44 magnetometer. The GRS 77 also utilizes GPS data forwarded from the GDU 620. Actual attitude and heading information is sent to the GDU 620 using an ARINC 429 digital interface.

Figure 1-5 GRS 77 AHRS

Appendix B Index Appendix A

The IGRF (International Geomagnetic Reference Field) model is contained in the GRS 77 and is only updated once every five years. The IGRF model is part of the Navigation Database. At system power-up, the IGRF models in the GRS 77 and in the Navigation Database are compared, and if the IGRF model in the GRS 77 is out of date, the user is prompted to update the IGRF model in the GRS 77. The prompt will appear after the G600 splash screen is acknowledged on the MFD.

1-4 Garmin G600 Pilot’s Guide 190-00601-02 Rev. E