Altitude Encoding
Posted: Tue Jul 18, 2017 6:57 pm
I have had my Sport HS EFIS providing altitude information to my GNS430 and GTX327 using the Fuel/Air Data Z Format for many years.
I have now replaced the GTX327 with an Appareo ESG transponder. It does not accept the Fuel/Air Data Z Format. I found that if I use the Trimble/Garmin encoding altimeter output of my EFIS, the ESG will function correctly. However that required that I change the altitude input format on my GNS430 to Icarus-alt. (the wiring from the EFIS splits to the GNS430 and the transponder).
I think the GTX327 needed air data to obtain GPS information primarily to know when the aircraft is in motion to switch from STBY to ALT mode. Since the ESG has a built in GPS, all it needs is altitude data. I think the same can be said of the GNS430, it only needs altitude data and not GPS or pitot airspeed data.
I think this is OK but would like confirmation.
Thanks
Jim Butcher
I have now replaced the GTX327 with an Appareo ESG transponder. It does not accept the Fuel/Air Data Z Format. I found that if I use the Trimble/Garmin encoding altimeter output of my EFIS, the ESG will function correctly. However that required that I change the altitude input format on my GNS430 to Icarus-alt. (the wiring from the EFIS splits to the GNS430 and the transponder).
I think the GTX327 needed air data to obtain GPS information primarily to know when the aircraft is in motion to switch from STBY to ALT mode. Since the ESG has a built in GPS, all it needs is altitude data. I think the same can be said of the GNS430, it only needs altitude data and not GPS or pitot airspeed data.
I think this is OK but would like confirmation.
Thanks
Jim Butcher