APPENDIX CTroubleshooting Q & A197190-00356-00 Rev GAppendix CTroubleshooting Q&AThis section is designed to answer some of thecommon questions regarding the 400W-series capabili-ties 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.What 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 NM for oceanic, 2 NM for en route, 1 NM for terminaland 0.3 NM for non-precision approaches).During oceanic, en route and terminal phases offlight, 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. The400W-series unit automatically monitors RAIM andwill warn you with an alert message (see Section 11)when it is not available, and the INTEG annunciator( ) will appear at the bottom left corner of thescreen. If RAIM is not available when crossing the FAF, thepilot must fly the missed approach procedure. The 400W-series unit RAIM prediction function will also allow youto see whether RAIM will be available for a specified dateand time.NOTE: RAIM prediction is not directly related toWAAS integrity.RAIM integrity prediction is performed by the internalGPS receiver and is performed at all times. WAAS integrityis reported by the WAAS satellite system and only workswithin the WAAS service volume. WAAS approaches re-quire WAAS integrity. Outside of the WAAS service vol-ume, such as an Oceanic flight, RAIM prediction will beused.Why aren’t there any approaches available for myflight plan?Approaches are available for the final destination air-port in a flight plan or as a direct-to (keep in mind thatsome VOR/VORTAC identifiers are similar to airport iden-tifiers). If a destination airport does not have a GPS ap-proach, the 400W-series unit will indicate “NONE” forthe available procedures—as listed on the airport approachpage. For more information on selecting an approach, seeSection 4 - Flight Plans, Select Approach.
