Is WASS GPS required for ADS-B out?

[Shawn]

Is WASS required for ADS-B out? I am seeing articles saying both yes and no.

Currently I have a 182P with 330 transponder, 430, 496, and Aspen single panel

I am looking to upgrade my Garmin 330 to a 330ES to get ADS-B out capabilities...I fly a lot in busy airspace and I really like the traffic picture with Foreflight and Stratus 2 but only have a 430...non WASS. The price for the 330 upgrade seems reasonable at about $1,200.

I am about to start IFR training and was thinking about upgrading the 430 to 430W or adding another WASS unit since marine layer and fog is gonna be a lot of my need for IFR flying and adding another unit would give me a third com radio which would be beneficial...but not sure I wanna spend that much dough with an engine rebuild looming.

My options are just upgrade the 330 to ES if the 430 works as is...upgrade the 330 AND 430 to 430W IF required for ADS-B out...or rather than throwing dead money at the 430, install a another WASS GPS and ditch the 496 since I NEVER use it. That will solve everything but end up costing four to five times what I wanna spend.

The WASS requirement may help decide which way I wanna go and how much I wanna spend now.

 

[poadeleted20]

The ADS-B-out rule requires WAAS GPS positioning data, but it does not require a WAAS GPS navigator like a GNS430W. If you have a WAAS GPS navigator, you can output positioning data from that to an ADS-B-out device and fill that square that way. If you don't have a WAAS GPS navigator, there are a couple of ADS-B-out devices either on the market or close which have a built-in WAAS GPS receiver chip to provide the necessary WAAS GPS positioning date internally without need of an external WAAS GPS navigator.

Of course, the ADS-B-out devices with a built-in WAAS chip will cost more than the ones which rely on externally-provided WAAS GPS positioning data, so if you have a WAAS GPS navigator, there would be no point in spending the extra bucks to get an ADS-B-out device with a built-in WAAS GPS chip. OTOH, if you don't have a WAAS GPS navigator and don't plan to get one, one of the ADS-B-out devices with an internal WAAS GPS chip would be the most cost-effective way to go to meet the 2020 ADS-B-out requirement. But on the third hand, if you already have a GTX330 transponder and a non-WAAS GNS430, for not much more than the price of a WAAS GPS-chipped ADS-B out box, you can get the ES upgrade to the transponder and the WAAS upgrade to the 430, and you get a ton more capability than you would otherwise.

 

[Brad Z]

Is WASS required for ADS-B out? I am seeing articles saying both yes and no.

Currently I have a 182P with 330 transponder, 430, 496, and Aspen single panel

I am looking to upgrade my Garmin 330 to a 330ES to get ADS-B out capabilities...I fly a lot in busy airspace and I really like the traffic picture with Foreflight and Stratus 2 but only have a 430...non WASS. The price for the 330 upgrade seems reasonable at about $1,200.

I am about to start IFR training and was thinking about upgrading the 430 to 430W or adding another WASS unit since marine layer and fog is gonna be a lot of my need for IFR flying and adding another unit would give me a third com radio which would be beneficial...but not sure I wanna spend that much dough with an engine rebuild looming.

My options are just upgrade the 330 to ES if the 430 works as is...upgrade the 330 AND 430 to 430W IF required for ADS-B out...or rather than throwing dead money at the 430, install a another WASS GPS and ditch the 496 since I NEVER use it. That will solve everything but end up costing four to five times what I wanna spend.

The WASS requirement may help decide which way I wanna go and how much I wanna spend now.

If you upgrade to the ES, you'll need a WAAS GPS input. Otherwise, you'll have to go the GDL 88 route. Get the upgrade, the LPV capability is worth it (not to mention not needing RAIM checks).

 

[John Collins]

WAAS is not a technical requirement, but as a practical matter, the position source requirements are stringent enough that most non WAAS position sources are not adequate to meet the FAA requirements. The FAA recommends that the position source be based on TSO C145/146 but permits position sources based on TSO C129 or C196. TSO C129 is the old version of a non WAAS GPS, and the sensor version has been replaced by TSO C196. Bottom line, your GNS430 doesn't qualify as a position source, but the GNS430W does qualify if it is at the appropriate software version.

The FAA has defined what they need as a position source in AC 20-165A and it permits TSO C129, C196, C145, and C146 based GPS receivers. You won't find any TSO C129 GPS units that will meet the requirements primarily because they don't provide some of the essential integrity and reliability data. I would suspect there will be some TSO C196 based sensors (non WAAS) that will qualify, but I am not aware of any that have as of this time. They may show up as integrated position sources sometime in the future.

Since you are getting an instrument ticket, I would recommend you upgrade your GNS430 to WAAS. It could then serve as the position source for an ADS-B Out device. Although the cheapest route to become compliant, once you have a WAAS GPS and the GTX330 is to then upgrade the GTX330 to ES, I would not recommend it over installing a GDL88. The latter will display weather and traffic on the GNS430W. Either solution will enable the traffic to be available on a portable device such as your iPad, ForeFlight, and Stratus combo, but the GTX330ES route won't display any ADS-B information on your panel equipment. To save money, I would sell the GTX330 and replace it with a lower cost mode A/C transponder such as a GTX327 or the Sandia unit.

 

[Shawn]

So sounds like the upgrade to at least a 430W would need to be in the plan. Just based on the cost of the GDL88, I think I would still just upgrade the 330 to ES.

Now the question is...is it worth it to spend the money to upgrade the 430 or bite the bullet and add a new WASS unit?

 

[AuntPeggy]

The capability of the 430W is limited by its '386 processor. Later equipment has about twice the capability. I have forgotten what you lose (by comparison) with the 430W or 530W.

 

[John Collins]

So sounds like the upgrade to at least a 430W would need to be in the plan. Just based on the cost of the GDL88, I think I would still just upgrade the 330 to ES.

Now the question is...is it worth it to spend the money to upgrade the 430 or bite the bullet and add a new WASS unit?

My GDL88 was $4,500 installed. To upgrade my GTX330 to ES would have been about $1500. So for $3000 I got panel mounted traffic and weather. Although I have a Stratus 2, iPad, and ForeFlight, I wanted the panel mount for traffic in particular. It is great on the panel and fully integrated. The portable is used mainly for charts and as a backup. With the panel mounted traffic, I can keep my head and outside and still get traffic via audio, "Traffic 2 O'clock, same altitude, less than a mile".

 

[bnt83]

I don't have any money invested in portable ADS-B and the Cardinal does not have any panel mounted GPS or display to support ADS-B (in or out) so my initial thought is:

NavWorxs ADS-600-BG transceiver which has an internal GPS sensor. With all the options for wired external display, and WiFi module to run ADS-B (in) to Wing X (and other apps) on the ipad.

It looks to have very similar performance as the GDL-88 but not require an additional wired external display to take advantage of the ADS-B (in) portion, for ~ the same $ as the GDL-88. (I've never heard of a WiFi option on GDL-88)

I haven't read the STC or installation instructions yet so there may be some catch in them.

 

[Jim Burns]

Keep in mind that the GTX330ES STC for ADS-B Version 2 compliance has the GNS and GTN WAAS GPS devices listed in the AML. Other devices may need a field approval to verify they meet the stringent position reporting requirements.

Upgrade your 430 to WAAS, upgrade your 330 to ES. No additional installation complications other than changing the GPS antenna and a RS232 output from the 430 to the 330.

 

[John Collins]

Keep in mind that the GTX330ES STC for ADS-B Version 2 compliance has the GNS and GTN WAAS GPS devices listed in the AML. Other devices may need a field approval to verify they meet the stringent position reporting requirements.

Upgrade your 430 to WAAS, upgrade your 330 to ES. No additional installation complications other than changing the GPS antenna and a RS232 output from the 430 to the 330.

FAA policy is that each combination of ADS-B Out equipment and position source must be approved by an STC. For STC's with an AML, they cover the specific aircraft model. If the STC is for a single model or the aircraft is not included in the AML, then follow on field approvals are permitted assuming the wiring interface is the same. New position sources can not be field approved without already having been approved as part of an STC.

Trig has been working for some time now on attempting to obtain an STC to use their TT31 (and their OEM variants) to use the Garmin GNS430W/530W as a position source. They hope to have it this summer, but time will tell. IOW, no first STC, no compliance.

 

[bnt83]

FAA policy is that each combination of ADS-B Out equipment and position source must be approved by an STC. For STC's with an AML, they cover the specific aircraft model. If the STC is for a single model or the aircraft is not included in the AML, then follow on field approvals are permitted assuming the wiring interface is the same. New position sources can not be field approved without already having been approved as part of an STC.

Trig has been working for some time now on attempting to obtain an STC to use their TT31 (and their OEM variants) to use the Garmin GNS430W/530W as a position source. They hope to have it this summer, but time will tell. IOW, no first STC, no compliance.

My understanding is that there are three different TSO specifications of GPS in this mess

430/530 does not and will not meet the ADS-B minimums.

WAAS is OVER the ADS-B's GPS TSO requirements and is accepted.

I would not be surprised if there is a minimum software version or mod status requirement buried in the STCs. If there was, you might buy a used 430w/530w and still have to send it out for upgrade/repair/etc. All speculation

 

[dukeblue219]

Keep in mind that you'll need your avionics guy to configure the 330ES in a particular manner in order to get full traffic on your iPad through the stratus. Since the Stratus receives that information through TIS-B on the 978 MHZ band, and your 330ES will be OUT-only on 1078, it will not automatically trigger the ground station to send up TIS-B in the airspace around your plane (afterall, it doesn't know you can receive on the 978 UAT frequency). You'll just get the same limited traffic you get already on the stratus.

The 330ES needs to broadcast that it is equipped with 978 UAT as an ADS-B IN receiver, which is a menu configuration setting. See http://www.pilotsofamerica.com/forum/archive/index.php/t-59070.html

 

[John Collins]

I don't have any money invested in portable ADS-B and the Cardinal does not have any panel mounted GPS or display to support ADS-B (in or out) so my initial thought is:

NavWorxs ADS-600-BG transceiver which has an internal GPS sensor. With all the options for wired external display, and WiFi module to run ADS-B (in) to Wing X (and other apps) on the ipad.

It looks to have very similar performance as the GDL-88 but not require an additional wired external display to take advantage of the ADS-B (in) portion, for ~ the same $ as the GDL-88. (I've never heard of a WiFi option on GDL-88)

I haven't read the STC or installation instructions yet so there may be some catch in them.

Brian,

The FreeFlight Ranger has its STC and I would expect it would install for $4500. It has similar function to the NavWorx box, includes the GPS and antenna as a built in approved position source and has a Wi fi option.

 

[bnt83]

Brian,

The FreeFlight Ranger has its STC and I would expect it would install for $4500. It has similar function to the NavWorx box, includes the GPS and antenna as a built in approved position source and has a Wi fi option.

I don't recall much about that box or what the difference is.

I'm an A&P IA so the box that is NOT "dealer installation only" would likely be the one I pick.

 

[zaitcev]

The FAA recommends that the position source be based on TSO C145/146 but permits position sources based on TSO C129 or C196.
(....)
To save money, I would sell the GTX330 and replace it with a lower cost mode A/C transponder such as a GTX327 or the Sandia unit.

Sorry to hijack Shawn's thread, but do you happen to know what numbers are good for the other side, the transponder? I'm looking at Trig TT22, which is about equivalent to Sandia's STX 165 in size, weight, and power consumption, but provides Mode S. Their claimed TSO is C166b.

-- Pete

Update: acutally AC-20-165A may be not as intimidating as I thought. It says:

ADS-B equipment meeting the minimum performance requirements of TSO-C166b or TSO-C154c that are directly connected to a position source meeting the minimum performance requirements of any revision of TSO-C145, TSO-C146, or TSO-C196 will typically meet the integrity latency requirements. For these systems you only need to demonstrate, through analysis, that a non-isolated GNSS satellite fault detected by the position source is properly passed to the ADS-B equipment and that the ADS-B equipment indicates an invalid position by transmitting the position integrity and accuracy metrics equal to zero.

 

[Marauder]

I have been keeping tabs on the Aspen ADS-B offerings. I would expect an announcement of the August availability (finally) at Oshkosh.

The big question is whether or not it is a repackaged FreeFlight.




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[John Collins]

I have been keeping tabs on the Aspen ADS-B offerings. I would expect an announcement of the August availability (finally) at Oshkosh.

The big question is whether or not it is a repackaged FreeFlight.




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I understand Aspen will offer the Trig and the FreeFlight stuff OEM.

 

[zaitcev]

I understand Aspen will offer the Trig and the FreeFlight stuff OEM.

Funny how Aspen is in town with Sandia, but Sandia bums refuse to upgrade their transponder to Mode S (I have an e-mail from them to the effect "Mode S is too hard, so just use UAT and buy our Mode C since you need it anyway with UAT"). What a laugh.

 

[John Collins]

Funny how Aspen is in town with Sandia, but Sandia bums refuse to upgrade their transponder to Mode S (I have an e-mail from them to the effect "Mode S is too hard, so just use UAT and buy our Mode C since you need it anyway with UAT"). What a laugh.

May be a laugh in your case, but it actually a very valid point for a lot of pilots. It is cheaper than a mode S and fully supports the anonymous mode available if you install a UAT based ADS-B unit. I expect to see Mode C transponders with integrated UAT units and a built in position source as one possible offering.

 

[Marauder]

May be a laugh in your case, but it actually a very valid point for a lot of pilots. It is cheaper than a mode S and fully supports the anonymous mode available if you install a UAT based ADS-B unit. I expect to see Mode C transponders with integrated UAT units and a built in position source as one possible offering.

I hope this happens. It will help a lot of owners who don't need the mode S versions.


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[John Collins]

I hope this happens. It will help a lot of owners who don't need the mode S versions.


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Most of the GA piston crowd won't need a mode S transponder as it is both more expensive and lower function than an existing mode A/C transponder with a UAT ADS-B system to satisfy the 2020 mandate. I suspect that many pilots are confused and think that they need a mode S transponder with ES. In most cases, nothing could be further from the truth.

In special cases, the mode S transponder is the way to go, but this is primarily appropriate if the aircraft is going to be flown at 18000 MSL or higher. Also, in some cases, aircraft already have a mode S transponder that is inexpensively upgraded to ES, and this may be a reasonable option. I was in the latter category, but chose to install a GDL88 (UAT) system as it had much more value to me than simply being compliant with a rule. I obtained both the traffic and the free weather on my GNS530W, neither of which would have been available had I chosen to upgrade my GTX330 to ES.