update notes as of 5/1/2016


  • All other aircraft with the Avidyne PFD are also eligible for the WAAS upgrades contingent on aircraft manufacturer's requirements.

  • All Cirrus aircraft with the "six-pack" (non SN3308) configuration will require the annunciators as listed under "Non-Basic WAAS Upgrades". We have now completed our first WAAS upgrade on an SR20 with a Sandel SN3308. Call for details.

  • All aircraft with the Sandel SN3308 will require some rework/rewire to allow the GNS unit to drive the SN3308 via analog data (most likely wired for serial now). This will allow the SN3308 to depict the required GPS vertical deviation. Note: The Sandel SN3308 can be wired to display all required annunciation with the exception of 'INTEG'. Rumor has it that Sandel may be having a 'change of heart' regarding a future software upgrade that will make the SN3308 more compatible with WAAS upgrades. Assuming this is true, a timetable has not been set.

  • All aircraft equipped with the STC ST-901 Steering Adapter will most likely require the installation of a relay or at least an additional wire run between the GNS and the ST901 converter. Note to all installers: If the 'GPS Annunciate' wire is already being used for a GPS 'active' annunciator, it is recommended that you do not parallel onto the 'GPS Annunciate' wire as is inferred by the Garmin 400W/500W installation/upgrade manuals. This can cause other problems. I have contacted Garmin and asked them to revise their documents. I am waiting their response.

  • The new WAAS upgrade will NOT permit operation of the Garmin GDL49 Weather Datalink System.

I hope this helps explain where we are and what is involved with the Garmin 400W/500W WAAS Upgrades. I am sure that for some individuals, this has raised a few more questions. Please feel free to contact me with those questions.





 T: +717-569-1953

500-U Airport Road, Lititz, PA  17543 · 717-569-1953

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Todd Adams

Lancaster Avionics Inc.


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