Garmin GNS 430 - Manual (Page 191)

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Appendix D: Troubleshooting Q & A
This section is designed to answer some of the common questions regarding the GNS 430’s
capabilities and operation. If you have a problem operating the unit, read through this appendix
and refer to the reference section noted. If you don’t find answers to your particular question here,
use the index to find the appropriate section elsewhere in this manual. If, after reading through the
appropriate reference section, you still haven’t found the answer to your question, please see your
authorized dealer or contact GARMIN directly at the address or phone numbers listed on page iv.
GARMIN is dedicated to supporting its products and customers.
TROUBLE-
SHOOTING
D APPENDIX
NOTE
If RAIM is not predicted to be available for the final approach course, the approach will not become active—as indicated
by an “Approach is not active” message, a “RAIM not available from FAF to MAP” message and the INTEG annunciator.
What is RAIM, and how does it affect approach operations?
RAIM is an acronym for Receiver Autonomous Integrity Monitoring, a GPS receiver function that performs a consistency check on all tracked
satellites. RAIM ensures that the available satellite geometry will allow the receiver to calculate a position within a specified protection limit (4 nm for
oceanic, 2 nm for en route, 1 nm for terminal and 0.3 nm for non-precision approaches).
During oceanic, en route and terminal phases of flight, RAIM will be available nearly 100% of the time. Because of the tighter protection limit on
approaches, there may be times when RAIM is not available. The GNS 430 automatically monitors RAIM and will warn you with an alert message
(see Section 10) when it is not available, and the INTEG annunciator ( ) will appear at the bottom left corner of the screen. If RAIM is not
available when crossing the FAF, the pilot must fly the missed approach procedure. The GNS 430’s RAIM prediction function (see page 146) will also
allow you to see whether RAIM will be available for a specified date and time.
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