ANPRM - removal of transponder exception for gliders

On Tuesday, June 16, 2015 at 1:44:47 PM UTC-4, Steve Leonard wrote:

On Tuesday, June 16, 2015 at 12:19:19 PM UTC-5, son_of_flubber wrote:

Is it reasonable to argue that a Trig TT21 (130 watt) should be acceptable for glider use due to my lower speed, rather than just the TT22 (250 watt)? Is there any chance that the FAA would grandfather in TT21s in any new regulations?


Son, your transponder (TT21) is already acceptable. No need to "grandfather" it.


My limited understanding... Due to the 130 watt output, the TT21 is not 2020 compliant, so even if I invested in a TSO'd GPS source, I could not use the TT21's ADS-B out capability. The 250 watt 2020 requirement is based on the closing speed of two aircraft and since a glider is slow (or stationary in wave) I'd conjecture that it was not needed. ADS-B out at 130 watts is much better than no ADS-B out.

From Trig website:

What are the differences between the TT21 and TT22?
Both models have the same physical dimensions and advantages of size and ease of installation. The TT21 is a 130 watt Class 2 transponder; this makes it ideal for light sports and regular GA use. The TT22 is a 250 watt Class 1 transponder, ideally suited to higher performance and/or high altitude performance types.
In the U.S. the FAA has stated that Class 1 transponders must be used to be '2020 complaint' For U.S. customers Trig recommends the TT22 unit for this reason.

On Tuesday, June 16, 2015 at 11:04:56 AM UTC-7, son_of_flubber wrote:
On Tuesday, June 16, 2015 at 1:44:47 PM UTC-4, Steve Leonard wrote:

On Tuesday, June 16, 2015 at 12:19:19 PM UTC-5, son_of_flubber wrote:

Is it reasonable to argue that a Trig TT21 (130 watt) should be acceptable for glider use due to my lower speed, rather than just the TT22 (250 watt)? Is there any chance that the FAA would grandfather in TT21s in any new regulations?


Son, your transponder (TT21) is already acceptable. No need to "grandfather" it.


My limited understanding... Due to the 130 watt output, the TT21 is not 2020 compliant, so even if I invested in a TSO'd GPS source, I could not use the TT21's ADS-B out capability. The 250 watt 2020 requirement is based on the closing speed of two aircraft and since a glider is slow (or stationary in wave) I'd conjecture that it was not needed. ADS-B out at 130 watts is much better than no ADS-B out.

From Trig website:

What are the differences between the TT21 and TT22?
Both models have the same physical dimensions and advantages of size and ease of installation. The TT21 is a 130 watt Class 2 transponder; this makes it ideal for light sports and regular GA use. The TT22 is a 250 watt Class 1 transponder, ideally suited to higher performance and/or high altitude performance types.
In the U.S. the FAA has stated that Class 1 transponders must be used to be '2020 complaint' For U.S. customers Trig recommends the TT22 unit for this reason.

A very cursory reading of TSO-C199 suggests that a TT21 would work for this, probably needing a firmware update. The transmit power required appears to be 70 watts.

If the proposed rule making and TS0-C199 equipment could be so aligned that existing ADB compliant installations (in gliders there are only 2 or 3 brands), preferably with cheap or existing GPS receivers can be made to work (and I can see no reason why it would be technically difficult) then for many private gliders the cost would be low. For gliders with no current Mode S transponder, the costs would be approximately what a transponder install costs today ($3K maybe?).

On Tuesday, June 16, 2015 at 10:44:47 AM UTC-7, Steve Leonard wrote:
On Tuesday, June 16, 2015 at 11:32:16 AM UTC-4, jfitch wrote:

Many who have fitted Mode-S transponders already have the equipment and electrical load to transmit position and velocity data to the collision avoidance system. If Flarm would just certify their GPS as TSO-C199 compliant, then many of us would already have the equipment required.

Nope, Jfitch. You would not. TABS will transmit your position for a TCAS enabled plane to see. Flarm does not do that. Only way to do that now is with a transponder. Maybe in a couple of years (the TSO for TABS was just released in October of 2014), there will be a complete, TABS system available. But, it will have to cost a whole bunch less than a transponder to draw any real interest in adoption.

On Tuesday, June 16, 2015 at 12:19:19 PM UTC-5, son_of_flubber wrote:

Is it reasonable to argue that a Trig TT21 (130 watt) should be acceptable for glider use due to my lower speed, rather than just the TT22 (250 watt)? Is there any chance that the FAA would grandfather in TT21s in any new regulations?


Son, your transponder (TT21) is already acceptable. No need to "grandfather" it.

Does PowerFlarm alert to TABS equipped aircraft?

No. PowerFlarm will not alert TABS equipped aircraft. PowerFlarm only "alerts" other Flarm devices as to your presence. TABS will be a "dumb" system, as it only talks. It does not listen. It will tell the heavies "Look out! Something is out here!" But it will not tell you "Look out! Something is trying to run over you!"

My read on this based on my current understandings.

Steve Leonard

I was not suggesting that the Flarm alone would alert TABS equipped aircraft, but the GPS already installed in the Flarm could be used as a GPS source for your already installed Mode S transponder, all that is then required is a cable.

The best solution for both gliders and light power is exactly this - using the installed Mode S capability as a transmitter and cheap GPS for not as capable - but still perfectly adequate for collision avoidance - substitute for ADS-B out.

My read of the proposed rule change is as follows:
The proposed change would lift the current glider exception. The current exemption allows us to not have a transponder (or ADSB or TABS in the future) when:
1. Fly within 30 miles of the class B (mode C veil) and under the shelf.
2. Fly above 10,000 feet MSL
3. Fly in class B or C.

What else?

Thanks,
Jamie Shore

On Wednesday, June 17, 2015 at 8:50:58 AM UTC-4, Jamie Shore wrote:
My read of the proposed rule change is as follows:
The proposed change would lift the current glider exception. The current exemption allows us to not have a transponder (or ADSB or TABS in the future) when:
1. Fly within 30 miles of the class B (mode C veil) and under the shelf.
2. Fly above 10,000 feet MSL
3. Fly in class B or C.

What else?

Your summary is correct, but it lumps together a range of possible outcomes. The FAA is not posing a YES/NO question.

A non-exhaustive enumeration of possible outcomes:

Outcome 0 - No change to current regulations

Outcome 1 - TABS required, Transponder not required, ADS B not required

Outcome 2 - TABS not required, Transponder required, ADS B not required

Outcome 3 - TABS not required, Transponder not required, ADS B in/out required

Outcome N - Some optimal combination of TABS, Xpndr, ADS-B,required.

The FAA solicits comments on the costs and benefits of any and all of the possible outcomes and then they will decide.

On Wednesday, June 17, 2015 at 7:50:58 AM UTC-5, Jamie Shore wrote:
My read of the proposed rule change is as follows:
The proposed change would lift the current glider exception. The current exemption allows us to not have a transponder (or ADSB or TABS in the future) when:
1. Fly within 30 miles of the class B (mode C veil) and under the shelf.
2. Fly above 10,000 feet MSL
3. Fly in class B or C.

What else?

Thanks,
Jamie Shore

My reading is that if all exemptions for sailplanes were removed from the language of FAR 91.215, then all sailplane operations within 30 nm of the airports listed in FAR 91 Appendix D section 1 would require transponders regardless of altitude. Not sure if that's the same as what you said or not.

S