Page 2-2 GNS 400W Series Installation ManualRev. G 190-00356-082.2.3 IFR VOR/LOC/GS InstallationThe minimum GNS 430W installation requires the following items for an IFR VOR/LOC/GSInstallation:GNS 430W (installed in the aircraft manufacturer approved location)GPS antenna, VOR/LOC antenna, glideslope antenna, and COM antenna.An External CDI/HSI indicator must be installed in the pilot‘s primary field-of-view (or in theaircraft manufacturer approved mounting location). The indicator must have a vertical deviationindicator for glideslope and VNAV operations/approaches.Any annunciation required for Source Selection or IFR GPS Navigation must meet acceptablefield-of-view requirements.2.3 External SensorsWhen the 400W Series unit is installed with external sensors, these sensors must be installed inaccordance with the manufacturer's data. This manual does not provide information for the installation ofspecific external sensors.The 400W Series unit can accept data from multiple altitude, heading, and baro correction sources. Ifmultiple sources are used, the 400W Series unit will accept data as described below.NOTEBarometric altitude is not required by the 400W Series unit to meet the requirements ofTSO-C146a.2.3.1 Multiple Uncorrected Pressure Altitude SourcesThe 400W Series can accept altitude from a Gray code or RS-232 altitude encoder, fuel/air data computer(FADC), ARINC 429 air data computer (ADC), ARINC 429 EFIS, and ARINC 429 traffic advisorysystem.If multiple sources of altitude data are supplied to the 400W Series unit, only valid data from the highestpriority source is used (input priority cannot be configured). If the highest priority source becomesunavailable, data is taken from the next-highest priority source. The priorities of the altitude sources areas follows (from highest to lowest):1. ARINC 429 ADC2. ARINC 429 EFIS3. ARINC 429 traffic advisory system4. RS-232 FADC5. RS-232 Altitude Encoder6. Parallel Altitude Encoder (Gray Code)
