John

Lots of great points here, some rambling comments on a few techncial things or things I could not follow...

On Friday, August 14, 2015 at 5:01:53 PM UTC-7, wrote:

The current FAA proposals for TABS with TSO-C199 look to cost around $6000 for each glider plus the cost of downgrading your current mode C transponder if you have one to a paper weight. Battery draw will be reduced for anyone with a transponder now such as Becker but obviously an increase for ships without Mode C today and needing to add TABS.

$6000 costs seem high. If I had to guesstimate an _upper_ cost for a TABS device in the near future, I'd expect something like a Trig TT-21 + $1,000 for a GPS source. That is based on triangulating costs for products like the new non-TSO $850 Garmin GPS 20A.. since it meets the full ADS-B our performance requirements having it pass the TABS approval tests should be relatively easy. And no I'm not implying that cost to be affordable or is justified for many glider pilots, just pointing out what I expect a high cost would be.

However that assumes sensible install regulations (anything close to the ADS-B Out STC mess that happened early on woudl be a disaster) and collaboration between vendors of Class A and B TABS devices.... and in general I expect dedicated TABS devices to just include a suitable GPS source. NexNav has announced their "low-cost" TABS Class B Micro-i GPS source. No real clarity on what they mean by low-cost, and I expect they will really sell to OEMs..


6 A significant risk is glider to glider near misses on high energy lines that are used for fast cross country flying and where gliders are working in close proximity in the same space. Power FLARM (FLight and AlaRM) is an existing and viable solution that is being progressively adopted in the US and the European version of this is highly successful with a decade of experience. Power FLARM (PF) shows transponder activity permitting avoidance action but is not itself seen by TCAS type devices nor ATC but can be used in the glider to provide an alert and activate a transponder/TABS.

I doubt anybody who is not a glider pilot will understand what an energy line are. Their loss :-)

Not all PowerFLARM actually receive 1090ES, most (all?) sold in the USA do. At one time there was talk of sales of models without 1090S In in the USA, I'm not sure if any sales actually happened (it's a very bad idea IMNSO becasue of 1090ES Out/possible future TABS compatibility).


8 TSO-C199 TABS is not yet available commercially and not understood by most of the US glider community. It appears to be just the lowest cost mode S transponder on the market today (TRiG TT21) with an external GPS WAAS (TN70) capability. The only concession from the authorities appears to be relaxation in the TSO process. Further this is a transponder class 2 that is only approved to altitudes to 15,000 feet. This is an expensive solution beyond the financial justification of many of the aircraft that will be required to install it.

There are no TABS Class A devices on the market today, and no manufacturer TSO approved. A Trig TT-21 might be a possible to use as a TABS device since the TABS TSO spec is (a good thing) designed to allow existing Mode S transponders to potentially be backed into use as TABS device. There is certainly *potential* for TABS devices to be say smaller/lighter than say even the current Trig packaged Transponder (which are *great* transponders), e.g. look at what Sagetech does today for Mode S UAV transponders.... http://www..sagetechcorp.com/unmanned-solutions/

Any actual TABS carriage and installation regulation for use in gliders would clearly need to allow that TABS device use above 15,000. The folks who developed the TABS standard understand that. The 15,000' limit in a Class 2 Transponder is not directly relevant in any technical sense here... Installation and carriage regulations or TABS devices needs to be developed, what that looks like if any, is important but it will need to be clearly separated from current transponder regulations...


9 Gliders, balloons, airplanes without electrical systems, and drones need their requirements studied, a single appropriate specification produced, and a commercial product developed. The electronics industry needs greater volume than just that provided by gliders to deliver a cost effective solution with ongoing development. Producing a specification with price, power, and size requirements that have yet to be defined is the first step. The recent proposals attributed to Google on low cost ADS-B transponders for drones show that development is far from over and early adopters will be penalized financially.

I expect the FAA would argue that is what TABS is intended to achieve, and lots of folks, including suppliers to the UAV/drone industry, had input into that TSO's development.


1 What was the specification defined for the TABS device? Especially cost, power, physical size, operating limitations e.g. 15,000 feet if that is a spec for the the class 2 transponder. What about glider operations to 18,000 and in wave windows (which ATC routes all other traffic around) to 40,000 feet and above?

TABS/TSO-C199 is a technical product standard. The FAA or RTCA standards just are not going to deal with things like physical size or cost, and that is a good thing, let the market work on that. The FAA can hand wave (largely correctly) that TSO-C100 targets costs by say allowing use of consumer GPS chipset technology (by the avionics manufacture, not owners/pilots connecting random consumer GPS devices), and leveraging exiting Mode S technology/Mode S manufacturer capability. And while all that is a big step for the FAA, TABS devices are still complex and are still likely to be relatively expensive until they reach some significant volume, and that won't even start to happen until there are carriage/install regulations. For better or worse I expect many players here want to make the glider community the test case.. But ultimately volume is going to need something like UAV use... not that I am excited about having larger UAVs flying around putting manned aircraft at risk.

There should not be a specific technical issue with TABS and 15,000'. And the folks developing the TABS standard understand this. But it is absolutely great to point out things like any TABS usage regulation should allow operation in wave windows (or maybe rather the FAA should be required to allow TABS devices in any wave window agreements that requires transponders and/or 1090ES Out devices). I'd have s similar wish for Class A airspace in general, but wave windows impact lots more glider pilots than the few doing Class A IFR flights.


5 What consideration has been given to glider on glider conflicts which typically are not in ATC radio contact and cannot not have TCAS type devices? Has a non TSO approval been considered for Power FLARM?

I am not following at all what you are asking for here with "non-TSO approval".

Do you want the FAA to mandate all gliders have to carry PowerFLARM? As well as Transponder? As well as TABS? or allowing PowerFLARM to drive TABS GPS? And what TSO? There is no TSO, or underlying RTCA standard at all that is really relevant to FLARM, nor is there any effort to develop one... any consideration about that was what ended up being TABS. And TABS per-se is just a beacon/output system, it does not require any input or display or anything close to Flarm for actual workable traffic warning in glider-on-glider situations. And how does the FAA approve a device without a TSO? The use of "non-TSO" products that's are made say in experimental aircraft requires a TSO spec for the device to be built towards, even if it's not actually TSO approved.

FLARM technology exists becasue it was possible to innovate and develop stuff for such as small specialized market without the usual high cost associated with regulations and bureaucracy. (It's amusing to think what the entire initial development cost of FLARM was and compare that to how many RTCA or FAA standards meetings you could actually conduct for that same cost :-))

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?

And I know you said TCAS-like, and I know you know what TCAS is but others reading this won't know what you mean exactly. Like what TCAS capability? You might have meant more ADS-B In traffic systems or various CDTI/ADS-B In solutions, but none of those systems will offer anything like TCAS-II RA capabilities. There is also a "cannot not" typo in there that is confusing.

And the FAA could point out there are already several choices of ADS-B in solutions that are compatible with TABS devices and all suitable to different extent in gliders... including obviously the 1090ES In option in PowerFLARM, as well as ADS-B In portable devices from Stratus and Garmin... but I really expect the glider community does not want the FAA pushing/mandating ADS-B In or similar product use in gliders.

6 How will ATC manage flight operations such as multiple gliders circling to gain altitude in the same thermal? Similarly gliders being launched behind a tow plane? And, formation flights where ATC typically asks for only the leader to operate a transponder?

This is not an issue with Mode S transponders, or TABS. And I would expect new transponders (including any likely to be installed due to removal of the exemption) are likely to be Mode-S transponders.

And it may be that this problem is overstated even for Mode C transponders. A lot of the folklore about this dates back to old Mode A/C SSR systems. In discussion with ATC staff (including radar techs) in places like Reno they strongly wanted gliders to be transponder equipped and were not concerned about this. I would be surprised if SSR and TCAS cannot handle synchronous garbling from a few aircraft (TCAS II for example has de-correlator designed to handle degarbling several overlapping transponders), large gaggles may be more of a challenge. But a large gaggle of gliders with Mode C transponders and possible synchronous garbling *is* going to get noticed on an SSR radar and ATC should help route traffic around that.

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

Airplanes are not a part of this ANPRM, and right now this should not really be a question... what towplanes requirements are is clear in the current regulations. But it ultimately would be an interesting thing to ask for TABS in special cases such as towplanes or maybe powered aircraft in general to provide partial coverage of where ADS-B Out will be needed after 2020. I hope AOPA and the EAA are watching this and willing to push on it if TABS does take off.

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?

I expect the FAA would argue that the SSA has been quite involved in this. For example the SSA has had representation at meetings that lead to the TSO-C199/TABS. I am not clear how much any of that has been discussed within SSA management or communicated to members.