Ads-b and sailplanes

Has anyone been following the latest moves from the FAA on ads-b and experimental aircraft? A recent article in flying suggested that they are going to relax the requirements for experimental planes so they need a GPS source that is equivalent in performance to TSO'd units.

If this is true, it might relax the requirements for those with Trig TT22 transponders so that they can use cheaper GPS sources like the GRT GPS-EXT-RAIM unit that they sell for just under $500.

I've decided that it's cheap enough to give a try, so I just ordered one and will be playing with it over the next few months. It certainly beats forking out $3000 on the TSO'd unit sold by Trig.

If anyone has opinions, experience or also intends playing with this I'd love to hear. I fly out of Harris hill which is right by a big iron airfield and it'd be nice to see them on a screen before bumping into them. I also like the idea of a couple of us flying with ads-b out so that people around us get to see the in portion. S emus like even a relatively small percentage of us on the new standard could help safety given the idiot decision by the FAA to restrict access to the "in" data to a hockey puck around each plane with "out".

Maybe next time try searching r.a.s. before asking a question. You would have found this has been covered in depth here recently...

Thanks for the help. Sentences like "TSO-C199 devices are a reduced feature Mode-S (and optionally 1090ES Out) based traffic saftey beacon system hopefully suitable for gliders, balloons and maybe UAVs inter-operating with GA and above aircraft equipped with PCAS/TCAD/TCAS/ADS-B In" are deeply helpful to those of us working our way into this topic. I'm deeply indebted.

Well, I have indeed discovered that you have strong opinions on the topic, and are able to command an impressive array of acronyms that it'd take me hours to google. Care to offer a newbie more than a dismissive flame?

On Wednesday, March 25, 2015 at 8:01:26 PM UTC-7, Andrew Ainslie wrote:
Well, I have indeed discovered that you have strong opinions on the topic, and are able to command an impressive array of acronyms that it'd take me hours to google. Care to offer a newbie more than a dismissive flame?

ADS-B Out GPS sources no longer need to be explicitly TSO'ed, they do need to "meet requirements of" the relevant TSO. That does not mean that any old random GPS will do. In fact no consumer GPS or any GPS with a NMEA output would be acceptable. The "RAIM" claims by GRT Avionics do not mean that GPS receiver "meet the performance requirements" of the relevant IFR GPS TSO.... it could not as is (since it only appears to communicate via NMEA), I expect they are doing some proprietary RAIM signalling to their own EFIS boxes. Who knows. Unless vendors are quoting exact TSO or RTCA specs things like saying the GPS has "WAAS" or "RAIM" become fairly useless marketing terms..

And that does not mean that an install in a certified aircraft (including glider) will not require a TSO'ed GPS. That minor wording change was mostly a win for the experimental powered aircraft folks, many of those owners will need to meet the 2020 ADS-B Out carriage mandate, and can now do so with non-TSO'ed GPS sources that "meet the performance requirements of...".

It has always been the case that in an experiential aircraft can install a non-TSO (and non-meets performance of...) GPS source for ADS-B Out as long as all the basic things are done right and the aircraft correctly transmits the appropriate SIL parameters to advertise it is using a non-complaint GPS source. However that will *not* meet the 2020 carriage mandate, and allow that aircraft to fly in airspace requiring ADS-B Out (again which glider are largely exempt from). And that "non-compliant" ADS-B Out carriage may or may not (it appears that it often does) result in the FAA ADS-B ground infrastructure today providing ADS-R and TIS-B service for that aircraft (in the hockey pucks around the aircraft you referred to), or certified airborne ADS-B receivers seeing that aircraft. And that situation may change (i.e. worsen) in future.

Your goal of wanting to have some aircraft flying around with ADS-B out so it would activate the FAA ground station based ADS-R and TIS-B services for nearby aircraft might seem attractive but is likely not useful at best, or a dangerous idea at worst. It's not useful if you expect the other aircraft to be gliders equipped with PowerFLARM receivers, as PowerFLARM does not receive ADS-R or TIS-B transmissions. Even if you had gliders equipped with suitable ADS-B receivers you still have the problems that ADS-R and TIS-B service volumes are are pretty shallow (e.g. +/- 3.500' for TIS-B) and you get the very bad traffic warning situation where if your aircraft is not equipped with ADS-B Out then you see traffic on your ADS-B In traffic display only near other ADS-B Out equipped aircraft, and once the traffic flys away from those other ADS-B out equipped aircraft, possibly towards you, they can drop off the traffic display. There is *no* way a pilot can look at any ADS-B traffic display and try to reverse engineer in their mind what is going on, what traffic is being painted for what client aircraft etc. You could help encourage very dangerous situations where pilots start thinking their ADS-B receiver can see/warn about traffic, and then all of a sudden the traffic actually a threat to them becomes invisible. If your glider is airborne and a client for ADS-R and TIS-B and you descent below service coverage (which might be pattern altitude or higher)then all of a sudden and with no warning to other pilots all TIS-B and ADS-R traffic show on all displays on all aircraft in that area could just disappear. If you want to use ADS-R and TIS-B safely you *need* ADS-B Out in your aircraft. That is just how the broken system was designed to work. The saving grace is hopefully most aircraft will equip with 1090ES Out, in which case any PowerFLARM unit will "see" them, independent of any ADS-B ground infrastructure/line of sight, radar coverage or having the glider ADS-B Out equipped.

So again, we get back to the old simple advice that if you fly gliders near busy airspace and are worried about running into fast jets and airliners etc. then by far the most effective technology related thing you can do is install a transponder... and it is fantastic to see you have. The 1090ES In part of a PowerFLARM can help point out some airliner/fast jet/high-end GA traffic to you, but especially with fast traffic you want them seeing/avoiding you with TCAS, and that takes a transponder. If you are worried about GA aircraft then the combination of a transponder and the PCAS part of PowerFLARM can be pretty useful.

All this stuff has been hashed out in other threads here before. If you don't understand much of this stuff or can't spend time Googling acronyms and working out what things means then you probably should not be worried about trying to be at the bleeding edge of this technology. It can be expensive to play with today, rapidly changing from a product viewpoint, and is just a technical and regulatory mess. Far too much crap for the average glider pilot to want to deal with. It is great that you already have a transponder installed in your glider, but now you spent $600 on a GPS receiver that will do nothing more for you techncially than any decent consumer/WAAS receiver, or just connecting to the NMEA out from a PowerFLARM (which I also hope you already have). Sure you can install this in your experimental category glider (you always could, even before the changed CFR14 wording you are referring to) with the appropriate SIL settings. It won't get you any closer to meeting 2020 carriage requirements (which was not your goal). And it *may* (apparently *should* at least today) trigger FAA TIS-B and ADS-R ground based services for your aircraft if you are in range of those ground stations (and you also have to correctly configure the CC/Capability Code bits in the Trig for it to advertise the aircraft has an ADS-B receiver and on what link layer).... but if your ADS-B receiver is a PowerFLARM it can't receive ADS-R or TIS-B to begin with, but it will keep seeing the 1090ES Out equipped traffic it is already seeing....

Oops somehow the opening few words of my first paragraph that should have started with "To meet the 2020 carriage mandate ..." Got deleted,

Thank you for the explanation, Darryl. I appreciate the time you put into your commentary.

Darryl,

Question regarding your statement that gliders are largely exempt from needing ADS-B Out to fly in 2020 inside some airspace which requires ADS-B Out.

I'm based inside a Mode C Veil. My glider has a TT21 equipped with the latest firmware 2.4 and 1.10 (I also have a PowerFlarm core providing ADS-B In).. Come 2020, since I have a Mode S transponder, I think I'll be required to install a C145a GPS that is known to work properly with my TT21.

Do you agree?

-John, Q3

On Thursday, March 26, 2015 at 6:46:08 AM UTC-4, Darryl Ramm wrote:
--snip--
It has always been the case that in an experiential aircraft can install a non-TSO (and non-meets performance of...) GPS source for ADS-B Out as long as all the basic things are done right and the aircraft correctly transmits the appropriate SIL parameters to advertise it is using a non-complaint GPS source. However that will *not* meet the 2020 carriage mandate, and allow that aircraft to fly in airspace requiring ADS-B Out (again which glider are largely exempt from).
--snip--

John, I'm sure Darryl will be along shortly.
Gliders are not required to have a transponder or ADS-B Out.
You are not required to add Out GPS data to the Trig unless you chose to. But if you do it must meet the standards.
FAA has recently reworded the language that allows "Experimental" kit built aircraft to install non TSO'd ADSB out systems as long as they meet the same standards. I'm not sure if that applies to experimental gliders.

We have Trig21 on some of our gliders, inside the Mode C Veil, we are not planning to add GPS to the Trig.
BillT

Darryl, I've been looking and for most standard certificated aircraft, not experimental, it takes STC to install ADS-B equipment. A couple of STCs I have found do not list the Piper Pawnee, PA-25. Any Pawnee I have seen is registered under Restricted category. Any ideas?
BillT