If the IFD is interfaced with a GAD29/29B/42/43. There could be an instance where the IFD will display: ![][1] The first thing that should be checked is the configuration. If the GAD is interfaced with a Garmin AP then the appropriate RS-232 setting should be EFIS/AIRDATA. If the GAD is interfaced to a 3rd part...
_Intro to IFD interfaces with EFIS systems_ _IFD Interfaced with Garmin G5 system_ _Troubleshooting IFD interfaces with EFIS systems_ _Main ARINC429 Config Page_ _VOR/ILS ARINC429 Config Page_ ...