VAF Forums

VAF Forums (
-   Glass Cockpit (
-   -   NavWorx ADS600-EXP and Class B airspace (

scrockard 02-14-2015 10:02 AM

NavWorx ADS600-EXP and Class B airspace
The ADS600-EXP deal this week seems pretty good but:

How will an ADS600-EXP system with: NavWorx external mounted antenna and GTX-327 transponder show up on an ATC system as compared to a fully TSO’d ADSB-out system?

One of the technical FAA guys at KOSH last year was trying to warn me about the “quality” of the ADSB-out system and how they may show you differently on their systems based upon the performance. The point being communicated was you may be treated differently in airspace as a function of how you display (even if you have ADSB-out broadcasting enabled)...

Here are my concerns:
Sec. 91.227 Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment performance requirements.

According to this requirement, we need to be looking at the following technical parameters when evaluating any purchases of ADSB out options:

(ADS600-EXP Specifications):

The ADS600-EXP is a Remote Mount ADS-B Transceiver with UAT OUT & IN, for use by EXPERIMENTAL AND LSA AIRCRAFT ONLY - Not for use by Certified Aircraft..

Experimental and LSA aircraft equipping with the ADS600-EXP are "good-to-go" for entering airspace mandated to have ADS-B on 1/1/2020.

Complies with the ADS-B Final Rule Technical Amendment, dated 2/9/2015, affecting 14 CFR 91.225 (b)(1)(ii) which permits ADS-B OUT in the National Airspace with devices that meet the performance requirements of TSO-C154c.

Transmits SDA = 2, SIL= 3
I don’t see anything about NACp, NACv, NIC etc here? It all comes down to how good the GPS position source is doesn't it?

scrockard 02-15-2015 08:34 AM

Note: there is an excellent thread that is showing how to obtain the accuracy report of installed ADSB equipment.


I would like to see this accuracy report from the FAA on an ADS600-EXP prototype.

Since this isn't shipping yet, this would have to be a report on a prototype unit from NavWorx.

maniago 02-15-2015 09:05 AM

Not really. Unless I'm mistaken, this is an "after the installation is complete" report. Doesn't help much to spend $5k or whatever, then get a report that tells you youre off the charts.

Kind alike buying any used piece of equipment without an 8130 or yellow tag etc....seems like Mr Reagan had it similar.... "Trust, but verify".

rvator51 02-15-2015 09:14 AM

It will be interesting to see. If it meets the TSO, then it should show up ok on the ATC system. The only difference would be the TSO paperwork. I am tempted to buy one at that price and just play with it.

Radomir 02-15-2015 09:55 AM

The unfortunate part is that it CAN show up as "pass" on the FAA report (for the most part and at least 99% of time). Majority of the report is what the unit sent.. there's some position verification (using the radar) but the unit it free to send out any signal it wants. (ie fully compliant even when it's really not).

Another competitor sends out "unbelievable" numbers -- such as GPS "accuracy" that is 2 orders of magnitude more precise than Garmin 430W and SIL and SDA numbers that don't pass the smell test.. So the FAA report just shows that -- what the unit sent.. Doesn't actually mean those units meet the performance standards..

It's an "honor" system for the most part.. and some units may either abuse it or stretch the borders a bit with that.

scrockard 02-15-2015 10:48 AM

I am agreeing with most of these comments so far.

Since NavWorx has been in this market for a long time and they do have a TSO'd version, I assume that if they are making the

Transmits SDA = 2, SIL= 3
in their specifications that they have completed at least the poor man's test on this particular unit (using the non-precise FAA report).

Also, I would venture to guess that the internal workings of this box are pretty similar to a much more expensive TSO'd version. Just a guess...

Is the internal GPS the same GPS source used in the TSO'd unit they sell??
This experimental unit looks like the same packaging as the TSO'd version...

Finally, isn't this price about what some ADSB-in only units are selling for? I'm sure NavWorx is thinking they are practically giving the model away at that price because it seems to pack so many features into one box.

mdevans9 02-16-2015 10:34 AM

GPS Specs are different
The specs published on Navworx website are different for the -600BG with TSO GPS (-143dBm Tracking; -137dBm Acquisition) than for the -EXP (-156dBm Tracking; -144dBm Acquistion).

No idea what the numbers mean and if the difference is significant.



scrockard 02-16-2015 07:36 PM

I like where you are going with the specification comparisons.

I found additional details for the certified external GPS in the ADS600-B installation manual. In this manual, the GPS has SBAS/WAAS features which appear to be missing on the uncertified GPS. There is nothing about WAAS performance on the ADS600-EXP that I can see either.

I also don't know enough about TSO and performance numbers to speculate much more...

Oh - and the price is now $729 today. lol!

Neal@F14 02-16-2015 08:38 PM


Originally Posted by scrockard

Oh - and the price is now $729 today. lol!

Webpage still says $699 but when you try to buy one it is $729. I was seriously interested in the device, but not anymore.

scrockard 02-16-2015 08:51 PM

It appears that the claim of: Transmits SDA = 2, SIL= 3 is no longer on the site either.... :confused:

All times are GMT -6. The time now is 03:53 AM.