View Single Post
  #15  
Old August 12th 15, 11:19 PM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default SSA responds to ANPRM

On Wednesday, August 12, 2015 at 12:57:41 PM UTC-7, Brian wrote:
Just be aware that if the exceptions go away ADS-B out will be required above 10,000 feet after 2020.


I know you use plural for exemption*s* but to make it perfectly clear to everybody, there are two separate exemptions, one for transponders and one for ADS-B. It is possible that the FAA could remove one of both exemptions and/or add TABS as an alternate carriage requirement.

While I can personally see some strong arguments for mandatory transponder carriage, especially near busy airspace I am a little less inclined to want to push for ADS-B, it's much more of a mess and still relatively expensive.. But with the FAA so committed to ADS-B hype, I'd hold out little hope for the FAA to not want ADS-B out carriage. If that does happen then at a minimum I expect the glider community needs to argue strongly to allow the alternate adoption of TABS (with favorable installation and carriage regulations). And I fully expect the FAA wants that TABS mandate, and knows that full 1090ES is impractical, but hey maybe a good hammer to pound the glider community with to make adopting TABS look a nicer option. And the question then becomes what exactly do the carriage and installation requirements for TABS look like (you don't want TABS install requirements looking *anything* like the early 1090ES Out STC based install procedures)?


if you have a transponder you will need to purchase an approved GPS source that currently costs about $3000 with installation.


If you have a *suitable* Mode S transponder.

There is no way of adding 1090ES Out to a Mode C transponder.... there could be an option of adding UAT-Out as a separate box but that is potentially a dangerous move with so many gliders being PowerFLARM equipped and not able to see UAT-Out equipped traffic.

if you don't have a transponder then you will to purchase and install a transponder as well for another $3000 or so.


If you don't have a *suitable Mode-S transponder*.

Not all Mode S transponders will be practically upgradeable to 1090ES Out, e.g. as I understand it some Becker Mode S units are not usable, but few if any of those are installed in gliders in the USA.

Also as I understand it the 150Watt Mode S transponder such at the Trig TT21, will not be acceptable after 2020 to meet the ADS-B out. So even if you have a transponder you may need to purchase another one.


Yes a good point, but frustratingly unfortunate thing for the FAA to do.

As you say, the Trig TT-21 will *not* meet the FAA 2020 ADS-B Out carriage mandate because Trig (and TT-21 owners) got screwed over by the FAA requiring higher output power transponders for 1090ES Out than required elsewhere in the world (presumably done by the FAA to save them costs on adding more ground stations)... a saving grace there would be to allow TABS carriage in place of full transponder + 1090ES Out as the TT-21 should meet that requirement. (Speaking only from the viewpoint of the TABS output power specs,actually getting at Trig TT-21 configured as a TABS device may require more work, maybe even a firmware update, likely will only have compatibility with specific GPS sources etc.). That is one of the reasons that if Transponder and/or ADS-B out exemptions were removed for gliders that TABS should be offered as an alternate means of compliance (but not necessarily providing access to all the same airspace.. but I'd hope for Class A being OK.). Having in place suitable TABS installation/carriage regulations would let Trig TT-21 transponders be used for TABS.


of course it is possible that the FAA may just modify the exceptions and allow only a transponder or 150W transponders or currently non-approved ADS-B out sources, or some other modification.

The FAA currently says it is ok to install non-Approved GPS source for ADS-B out in experimental aircraft, but is unclear if this will be acceptable to use above 10,000 feet or not (seems like probably not)


You can effectively install a wide rang of GPS sources in ADS-B Out in an experimental aircraft today... but the moment you want to use that to meet the requirement of the 2020 Carriage mandate you must use a suitably TSO'ed GPS source, of if in an experimental aircraft you can also use a "meets performance requirements of...(relevant TSO) " GPS source. And the FAA is threatening that if you don't have such a TSO'ed or "meets requirement of... (TSO)" GPS source the FAA ADS-B ground infrastructure (that delivers ADS-R and TIS-B services) will stop working with your ADS-B Out device in future.

A "meets the performance of... (some TSO)" is very different from any old GPS source. With the "meets performance of..." usually just deferred to the manufacturer documenting that the device meets that performance of whatever TSO. The CFR 14 regulation language around this type of stuff is very consistent and I would expect any similar "meets performance of..." to apply to GPS sources used in gliders, either for 1090ES Out full compliance or TABS.. A glitch in similar wording there for the 2020 ADS-B Out carriage mandate that was not consistent was changed in the last year or so after pressure from the EAA. And I expect that "meets performance of.." wording would be used in any future regulation changes for gliders just as it does for experimental power aircraft, including today above 10,000' and EVEN MORE experimental aircraft can use that after 2020 to operating in Class A, B and C airspace including IFR flights (i.e. notionally a lot more stringent than most gliders would ever experience).

Whether or not anybody agrees with removing carriage exemptions, if they do end up being removed then it is important that the SSA (with help from the EAA etc.) monitors any such regulation development to ensure that "meets performance of..." language also applies to GPS sources for ADS-B Out and TABS in gliders. That should be a minor thing, and hopefully the FAA wants to see worded that way anyhow.



Brian