John

Great stuff, let me try to cut stuff out and reply to some points. Sorry if I mangle this even further.

I think your submission is great, there are just a few things there that I see there, some of which have also come up in questions from other folks as well. And maybe this will help folks out.

I'm hoping this helps, not trying to be a pain.

Darryl

On Saturday, August 15, 2015 at 12:34:15 PM UTC-7, wrote:
Darryl

costs were based on Trig list prices of $2800 for their TT21, plus ~1000 for the GPS WAAS box, and 1900 for solar panels (recent quote), with a conservative $500 for instillation. I put this in one of the answers to the ANPRM specific questions and apologize for not commenting on the inclusion of solar in the costs. I may well be wrong but I don't think the FAA gave much thought to our costs and especially in the lower cost machines in the fleet

Thanks for that, it's a great way to highlight power concern/possible costs.. I'm a little doubtful about the cost/return of Solar Panels for many owners, they don't deliver as much power as some folks think, and I flew with large Strobl panels for several seasons. They were kinda handy for charging when the glider was left tied down etc. and the batteries are not removable for ground charging. For lots of gliders I'd hope larger/more modern batteries are a possible option. The corner cases of installing batteries, dealing with STCs, for older gliders are a serious worry... where those gliders may be far distant from high density traffic areas.

By suggesting class 2 I suspect the FAA does not understand that gliders operate over 15000. So I don't think we can assume that TABS will allow use to 18,000

The folks involved in the FAA development of TABS do understand this. The "Class 2" is just a way of saying... base this standard on a sensible existing low-power transponder RTCA standard to let manufacturers leverage existing designs/tests/approval processes etc.. it does not imply any 15,000' operational limitation on what a TABS device is designed to do.... (it's not designed to primarily operate as a legacy Mode A/C/S transponder for SSR interrogation.. which is what drove the legacy 15,000' Class 2 limit).

There is absolutely nothing wrong with stating that need, and it is probably good to do so. I just did not want people assuming there is necessarily a problem with TABS at 15,000' or sending too much time on this when they may want to prioritize other points they want to make.

9

I don't know if the FAA took a clean sheet of paper to write the TABS spec considering issues that will affect us such as power draw etc or simply decided the lowest power currently existing class 2 transponder would be OK and picked the TRiG TT21. The volume alone for gliders will not interest the suppliers very much. Unique to gliders and especially in the west is the need to operate upto 18,000

TABS/TSO-C199 is far from a clean-sheet design, it obviously leverages Mode S/1090ES but directly in the process to get there it derives from previous regulatory/standards work on LPSE (Low Power Surveillance Equipment)/ Low Power Mode S, especially in Europe. Those European organizations will be watching what happens in the USA...

Believe me folks involved in this know it has to work at least up to the floor of Class A airspace. Remember that the FAA development of TABS is directly in response to the NTSB pressure from the mid-air with the Hawker jet over the Pinenuts, and regardless what actually was the collision height, the NTSB is very clear the issue extends right up to Class A and that is broadly understood.

Again, there is no harm in stating that need clearly for TABS carriage/use regulations.

5.
if gliders with TABS turned it off to save power had PF then that would advise of an airplane threat and TABS could then be turned on from standby to provide a signal

That is a neat idea, but unfortunately it has some serious problems, that I suspect are, like lots of ADS-B things maybe not obvious.

PowerFLARM (assuming a version with 1090ES In) only directly "sees" nearby 1090ES Out equipped aircraft. (Because of it's European roots it will not receive UAT direct or ADS-R or TIS-B transmissions and even if PowerFLARM could receive ADS-R or TIS-B, the FAA ground infrastructure would not provide those services unless the TABS device is transmitting on 1090ES.. an interesting Catch 22 situation (oh what a fun complex mess ADS-B is).

A PowerFLARM may see other transponder but not 1090ES Out equipped aircraft via PCAS (most UAT Out equipped aircraft would also have a transponder, but it's not guaranteed they will), but even then PCAS may not provide a reliable/far enough warning. And even though TABS is largely abotu aircraft-aircraft sensign and collison avoidance the device is seen by ATC, the FAA ground infrastructure would not 'see" the glider's TABS device when it is turned off, or it would appear and disappear at different times, say when a controller might be looking out into the distance to provide separation or traffic advisories, not a situation I expect ATC folks would be happy with. So while an interesting idea it probably has enough issues that it may not be worth pursuing. What I expect will really get TABS power use down, is competition in the market, (and for better or worse) a market developing for TABS use with UAVs/drones.

I am kinda just lost about this point why would you want anything TSO or any other imaginable FAA approval or the FAA involved at all in anything related to PowerFLARM?
Don't want it TSO of course as we would likely never get that but want instillation permitted in standard cert aircraft.

I'm still not clear what you are asking exactly, and the FAA might be equally confused. PowerFLARM can be installed today in certified gliders.... especially because it is not being used to meet any FAA requirement. I suspect this general area may just be best to avoid getting into.

TCAS is of course understood by FAA for whom it is intended. They say that current TCAS will continue to be useable but the new TCAS spec will avoid the interrogation need of signals as they will be provided that data by ADS-B

It sounds like you are talking about the "hybrid surveillance" capability in the *current* TCAS II 7.1 spec? That technology uses ADS-B to provide long range surveillance of other aircraft and to avoid pinging their Mode S transponders (which helps save bandwidth.. but a huge bandwidth hog is Mode C transponders near TCAS.. IMNSHO it would have been better long long ago for the FAA to start a slow phase out of Mode C transponders,.. another very seperate discussion). The TCAS II transponder interrogator takes over for closer aircraft, and RAs are only every issued based on transponder interrogation. TABS devices are designed to fully work with TCAS II 7.1.

There is just no pure ADS-B based collision avoidance technology that will replace TCAS II on the horizon, the (huge) step of getting there would be RTCA development of a relevant standard. And there are very good security related reasons to not want a last-ditch collision avoidance technology like a TCAS II RA to rely on ADS-B alone... for that reason alone I hope TCAS II stays around for a long while.


Mode C is still required with within a TABS device or stand alone. Mode A has to be rejected by TABS spec

Legacy Mode C SSR interrogation is supported in TABS devices, but SSR and TCAS II systems will largely interrogate them via Mode S. I believe, but am not entirely sure, some of of the arguments for leaving the Mode C support in there is compatibility with old TCAD systems that interrogate Mode C only, and for broad applicability of the standard with very old legacy Mode A/C only SSR (should no really be a factor in the USA).

Be careful with "Mode A has to be rejected by TABS". TABS supports the "Mode A" squawk code. It's there, and critically important.. e.g. that squawk code is transmitted by the TABS 1090ES out with ATC will see, but you are correct that a TABS box won't reply to old legacy Mode A SSR interrogations.. and there is just little need to so just dropping it from the requirement simplifies things. That squawk code over 1090ES Out is how ATC will be able to tell a TABS equipped aircraft is a glider, is squawking a code for an emergency etc.

I asked this question and was told that ATC will still see a cluster of "hits" and yes could route traffic around that area. But they cannot determine if a glider on glider incident is about to happen. ATC can suppress data on their screen but will they restore it when the gaggle breaks up a few minutes later? I don't believe this has been considered by the authorities.

But ATC just cannot can't help if a glider on glider event is about to happen... there is no way they have enough positional information, can pay the necessary attention and neither should glider pilots want them to. ATC can see that what they are seeing on their displays are gliders and know not to worry about that glider-glider traffic conflict. I am just not sure this is worth worrying about.


7 Will tow planes require TABS or full ADS-B compliance?

In most parts of the country tow planes can operate below 10,000 but not high altitude airports in the west. If tow planes had the same requirements as gliders it would be cheaper for the operators who are in large part financially challenged.

I agree it is a *great* thing to ask for, but the comment was written could be read that there is confusion about current regulations. To be clear I suspect a good way is to state that the current regulations are clearly ... but that it could makes a lot of sense to allow tow planes to utilize TABS in future becasue ... (and I would hope that tow planes make a great test case for TABS in powered aircraft and that may get support from other aviation organizations).


9 Has the inclusion of representatives of the soaring community been considered for the planning process to get sensible products and procedures defined and implemented?

Yes I am sure the FAA had input on the spec creation from people such as SSA. Based on the SSA response to the ANPRM does that make you feel good?

No not really. I was simply pointing out how I expect some FAA folks would respond to that comment.