APPENDIX CTroubleshooting Q & A213190-00357-00 Rev GWhat is RAIM, and how does it affect approach opera-tions?RAIM is an acronym for Receiver Autonomous Integ-rity Monitoring, a GPS receiver function that performs aconsistency check on all tracked satellites. RAIM ensuresthat the available satellite geometry will allow the receiverto calculate a position within a specified protection limit(4.0 NM for oceanic/remote and 2.0 NM for en route,1.0 NM for terminal and 0.3 NM for non-precision ap-proaches).During oceanic, en route and terminal phases of flight,RAIM is available nearly 100% of the time. Because ofthe tighter protection limit on approaches, there may betimes when RAIM is not available. The 500W-series unitautomatically monitors RAIM and warns you with an alertmessage (see Section 12) when it is not available, and theINTEG annunciator ( ) appears at the bottomleft corner of the screen. If RAIM is not available whencrossing the FAF, the pilot must fly the missed approachprocedure. The 500W-series unit RAIM prediction func-tion (see Section 9 Aux Pages - Utility Page - RAIM Predic-tion) also allows you to see whether RAIM will be availablefor a specified date and time.NOTE: RAIM prediction is not directly related toWAAS integrity.RAIM integrity prediction is performed by theinternal GPS receiver and is performed at all times.WAAS integrity is reported by the WAAS satellitesystem and only works within the WAAS servicevolume. WAAS approaches require WAAS integrity.Outside of the WAAS service volume, such as an Oce-anic flight, RAIM prediction will be used.Appendix CTroubleshooting Q & AThis Appendix is designed to answer some of thecommon questions regarding the 500W-series capa-bilities and operation. If you have a problem operatingthe unit, read through this appendix and refer to thereference section noted. If you don’t find answers toyour particular question here, use the index to find theappropriate section elsewhere in this manual. If, afterreading through the appropriate reference section, youstill haven’t found the answer to your question, pleasesee your authorized dealer or contact Garmin directlyat the address or phone numbers listed on page ii.Garmin is dedicated to supporting its products andcustomers.
