On Saturday, January 31, 2015 at 3:00:07 PM UTC-8, George Haeh wrote:
The Europeans can use ADS-B Out today in gliders. There may be elements
similar to FAA TSO-C199 which I just heard about.

I still question why WAAS GPS is/will be the price of admission to
controlled airspace at least in VFR. Yes on a Cat III ILS, WAAS is
warranted.

http://www.glidertracking.com/connecting-ads-b/

"René de Dreu from the Glider Pilot Shop has put together a document which
examines possible ADS-B connections between all Mode-S transponders and LX
flight computers / equipment. "

Unfortunately dead link for time being:

http://www.gliderpilotshop.nl/winkel...roducts_id=490

Right, but it's kind of the reason that the Europeans can use 1090ES Out in gliders today is there are no applicable ADS-B services they interface to (including ATC) and no regulations beyond the most basic transponder/1090ES out requirements they have to meet. In a way it is not too different than the non-certified gliders in the USA, those owners can install any GPS source with the same 1090ES capable transponders.... but in the USA that has limited use as it is not enough to get the FAA ADS-B ground stations to want to send you ADS-R and TIS-B services and you likely won't even show up on traffic displays of aircraft with certified ADS-B In systems. In Europe where there are ADS-B Out requirements/standards for high-performance aircraft which require Certified IFR GPS sources. So just kind of a worse case paranoid warning: what Europe exactly will do in future is not guaranteed. If say they were to mandate ADS-B Out for lower performance aircraft than the current ADS-B Out mandate for high-performance (which is just rolling out) then who knows what might be required as a GPS source in those aircraft. But yes, damn it, things like testing/encouraging current COTS GPS use in the UK is great.

The issue that the FAA would argue with requiring a TSO/IFR/WAAS GPS source is not ultra-precision as it is with GPS reliability and failure detection.. I am just saying what they would argue :-)

BTW European agencies should be well aware of the stuff behind TSO-C199. Actually that TSO has some European roots back to low power Mode-S transponders... which in the past tied in with some concern about UK airspace restrictions/mandatory Transponder (or low-powered Transponder) carriage. So the other warning here is be careful what you wish/want to encourage without watching out for what might end up encouraging/enabling excessive mandatory use/restrictions.

And again the technical part of actually connecting together this stuff is not the problem, its actually pretty simple. And you can do that today in an experimental glider in the USA. You must be careful and properly set up the ADS-B out to report it is not using an IFR/TSO GPS source, and as a result it has limited use, you won't receive those services you might expect and it does not allow flight in airspace that would require a 2020 Mandate compliant ADS-B out system (gliders have exemptions for some airspace, but a non-compliant install won't get you into the other airspace). But geeks with experimental gliders may still want to do this (and a few have).

I'm not defending the FAA, but they had huge issues with ADS-B being everything to everybody and ADS-B is a key part of the ambitious and underfunded NEXGEN project. But the highly complex dual-link ADS-B approach in the USA is a mess and was a very bad idea for many reasons. Not allowing a COTS GPS for VFR traffic (at least outside certain airspace) was also a bad idea. TSO-C199 is interesting, I take it overall as a good sign, but it is unclear at least to me where it will end up and what products will actually come from it. It could also hopefully be a model for future broader changes to allow more use of non-TSO GPS for general ADS-B Out. And I still have some paranoid reservations where TSO-C199 could lead long term as mentioned above. Europeans pushing ahead with COTS GPS trials/encouraging use is a great sign as well, but again, does not mean they won't end up in future requiring higher-spec ADS-B Out installs in GA and gliders etc. (but we all hope they do not, and so far in what they actually have and have not done with ADS-B shows a lot more modest/overall rational/pragmatic thought than in the USA).

This ADS-B mess is still mostly futureware(*) for glider pilots in the USA, we just don't know exactly where this will end up, whether we'll ever see say TSO-C199 devices, whether ADS-B Out GPS requirements will be relaxed, etc. And Transponders and/or PowerFLARM are very useful, pretty well understood and realtively easy to deploy traffic awareness and collision avoidance assistance actually available and usable today. And since ADS-B Out is not even mandatory for gliders in 2020 it's just not worth most glider pilots worrying about.

(*) the part that of ADS-B that is not futureware for USA glider pilots is of course that the PowerFLARM with 1090ES In capability can "see" aircraft nearby that are transmitting 1090ES Out.