Does Garmin offer a product to make the internal GPS on the G3X a WAAS capable GPS? Dynon offers such a product or at least that was what I was told so I thought Garmin might as well.
I currently have a GNS480 which I planned to use as the WAAS GPS source for the future ADS-B out requirement but I have just been told that it is not currently able to do this. Supposedly there is an upgrade in the works at Garmin for the GNS480 to make it WAAS capable for this future requirement ( I believe its called MOPS). If this is true can you give me a guess as to cost and time frame of the upgrade to the 480. To make matters probably worse, my unit is actually an Apollo CNX80 so if the above happens to be true, will it be applicable to the Apollo unit as well?
If the G3X can not be made MOPS WAAS capable by some peripheral device (other than GNS400, 430 or 530), are there any plans to make something that will in the foreseeable future?
Thanks very much,
Brad Hood
Dynamic Aerosport
Hello Brad,
The GPS receiver installed internal to every G3X display is already a
WAAS GPS receiver and every one of these displays that has ever been shipped are likewise equipped with a WAAS GPS receiver.
We realize, however, that WAAS capability alone isn't really your question and you are asking if the WAAS GPS receiver inside the G3X display is or can be made to meet the requirements of FAR 91.227 as it relates to the position source requirements for ADS-B Out.
This is a very long story, and we could point you off to several previous threads, but we will try to make this short.
There are many requirements in FAR 91.227 relating to ADS-B Out, but this section defines the performance requirements:
(c) ADS-B Out Performance Requirements for NACP, NACV, NIC, SDA, and SIL--
(1) For aircraft broadcasting ADS-B Out as required under Sec. 91.225 (a) and (b)--
(i) The aircraft's NACP must be less than 0.05 nautical miles;
(ii) The aircraft's NACV must be less than 10 meters per second;
(iii) The aircraft's NIC must be less than 0.2 nautical miles;
(iv)
The aircraft's SDA must be 2; and
(v) The aircraft's SIL must be 3.
(2) Changes in NACP, NACV, SDA, and SIL must be broadcast within 10 seconds.
(3) Changes in NIC must be broadcast within 12 seconds.
We highlighted what is probably the most important requirement as it relates to using a non-certified WAAS position source. While
FAR 91.227 points to TSO?C166b and TSO?C154c to explain the meaning of "SDA = 2", Figure 9 of
AC 20-165 makes it very clear.
A position source with an SDA of 2 must have less than a 10E-5 probability of failure causing transmission of false or misleading information and must have Level C hardware and software design assurance per DO-178B for software and DO-254 for hardware.
Sorry to give you a headache, but this is what those of us trying to use non-certified position sources are up against. Our non-certified position sources, while having very high performance, do not have Level C or higher hardware/software design assurance, so they don't presently meet the requirements of FAR 91.227 as required for 2020 compliance.
As you probably know, G3X systems without certified position sources (like GNS/GTN units) are transmitting ADS-B Out today with their internal WAAS GPS and GTX23ES or GTX330ES Mode S transponders and enjoying the benefits of ADS-B, but the SDA parameter is set to 0 (indicating non-certified design assurance). Perhaps the regulations will change by 2020 allowing VFR aircraft to continue to use non-certified position sources for ADS-B Out like we do today, but we don't know.
With regard to your question about the GNS480 software update, the GNS 480 software was updated in April 2015 to provide the ADS-B Out+ capability required to use it as a FAR 91.227 compliant position source. See
this posting for details on the software versions.
Thanks,
Steve
