Pitot/static leak issues when using a "squat switch"

[[email protected]]

Darryl, Ramy, Williams, et al

After installing a squat switch (such as the Peregrine brand), did your plumbing pass a pitot/static leak test?

I have heard gossip of the Peregrine switch having pitot/static leak issues. Is there another approved squat switch known not to leak?

[Darryl Ramm]

I am not aware of any systemic problems, never heard of a single failure of these switches. I don’t know how to respond to “I’ve heard� stories. Who/what/when? ... if you want to contact me offline. This part was approved as part of the TT22/TN70 STC. Obviously any part can fail, and pneumatic connection can leak And the installer should do whatever test they usually would when touching a aircraft pneumatic system. This actual series of World Magnetic switches are the same ones I used for year in scientific equipment applications, frequently abused and never failed.

[Scott Williams[_2_]]

On Friday, November 22, 2019 at 2:01:42 PM UTC-6, wrote:
> Darryl, Ramy, Williams, et al
>
> After installing a squat switch (such as the Peregrine brand), did your plumbing pass a pitot/static leak test?
>
> I have heard gossip of the Peregrine switch having pitot/static leak issues. Is there another approved squat switch known not to leak?

This last summer I installed the Perigrine ground/air speed switch, with a small syringe applying just enough pressure to read 50 knots airspeed, reading is steady as a rock for over 20 minutes during a transponder-Ads_b check.
Good Luck,
Scott

[JS[_5_]]

On Friday, November 22, 2019 at 2:33:56 PM UTC-8, Scott Williams wrote:
> On Friday, November 22, 2019 at 2:01:42 PM UTC-6, wrote:
> > Darryl, Ramy, Williams, et al
> >
> > After installing a squat switch (such as the Peregrine brand), did your plumbing pass a pitot/static leak test?
> >
> > I have heard gossip of the Peregrine switch having pitot/static leak issues. Is there another approved squat switch known not to leak?
>
> This last summer I installed the Perigrine ground/air speed switch, with a small syringe applying just enough pressure to read 50 knots airspeed, reading is steady as a rock for over 20 minutes during a transponder-Ads_b check.
> Good Luck,
> Scott

Anyone had problems with these switches detecting an airspeed low enough in thermals to switch it to "on the ground" mode?
Jim

[Darryl Ramm]

The trip airspeed is much lower than 50 knots.

This is a perfect example of a r.a.s. thread creating concerns out of nothing.

These work. Stop worrying about stuff and get things done.

[Dan Marotta]

An interesting question, but I seldom look at the transponder control
head (TT22) to tell.Â* I do know that, when I turn the transponder on, it
reports GND on the screen and every time I've looked in flight (not that
often) it has always said, ALT.Â* I have noticed on my ClearNav II that
the ground speed has never shown less than 40-something knots except
while flying in wave but, again, I don't look at the ground speed that
often.

On 11/22/2019 4:23 PM, JS wrote:
> On Friday, November 22, 2019 at 2:33:56 PM UTC-8, Scott Williams wrote:
>> On Friday, November 22, 2019 at 2:01:42 PM UTC-6, wrote:
>>> Darryl, Ramy, Williams, et al
>>>
>>> After installing a squat switch (such as the Peregrine brand), did your plumbing pass a pitot/static leak test?
>>>
>>> I have heard gossip of the Peregrine switch having pitot/static leak issues. Is there another approved squat switch known not to leak?
>> This last summer I installed the Perigrine ground/air speed switch, with a small syringe applying just enough pressure to read 50 knots airspeed, reading is steady as a rock for over 20 minutes during a transponder-Ads_b check.
>> Good Luck,
>> Scott
> Anyone had problems with these switches detecting an airspeed low enough in thermals to switch it to "on the ground" mode?
> Jim

--
Dan, 5J

[Dave Nadler]

On Friday, November 22, 2019 at 3:01:42 PM UTC-5, wrote:
> I have heard gossip of ... leak issues.

Cure for squat leaks: https://tinyurl.com/ycvg3to4

[[email protected]]

On Sunday, November 24, 2019 at 10:56:03 AM UTC-5, Dave Nadler wrote:
> On Friday, November 22, 2019 at 3:01:42 PM UTC-5, wrote:
> > I have heard gossip of ... leak issues.
>
> Cure for squat leaks: https://tinyurl.com/ycvg3to4

Well, that depends.

[[email protected]]

On Sunday, November 24, 2019 at 4:51:37 PM UTC-8, wrote:
> On Sunday, November 24, 2019 at 10:56:03 AM UTC-5, Dave Nadler wrote:
> > On Friday, November 22, 2019 at 3:01:42 PM UTC-5, wrote:
> > > I have heard gossip of ... leak issues.
> >
> > Cure for squat leaks: https://tinyurl.com/ycvg3to4
>
> Well, that depends.

Can someone point me to the regulation that requires an experimental glider to install a squat switch along with adsb?

[Darryl Ramm]

On Monday, November 25, 2019 at 8:39:51 PM UTC-8, wrote:
> On Sunday, November 24, 2019 at 4:51:37 PM UTC-8, wrote:
> > On Sunday, November 24, 2019 at 10:56:03 AM UTC-5, Dave Nadler wrote:
> > > On Friday, November 22, 2019 at 3:01:42 PM UTC-5, wrote:
> > > > I have heard gossip of ... leak issues.
> > >
> > > Cure for squat leaks: https://tinyurl.com/ycvg3to4
> >
> > Well, that depends.
>
> Can someone point me to the regulation that requires an experimental glider to install a squat switch along with adsb?

There is no regulation that says that. Nobody here (including me) has ever claimed there is AFAIK.

The relevant bit is hidden in 14 CFR 91.227 (d)(1)

...Minimum Broadcast Message Element Set for ADS-B Out. Each aircraft must broadcast the following information, as defined in TSO-C166b or TSO-C154c......

(1) The length and width of the aircraft;

Length and Width of the aircraft are only transmitted in ground mode messages. So this regulation says for 2020 Compliance the system must be capable of switching to ground mode. But I (and others) interpret the intro wording "each aircraft must..." as a direction that this change must be automatic. It's not saying each aircraft must be capable of being put in air/ground mode by a pilot. It's saying the aircraft must... Now it's sure not very well worded but that requirement is how manufacturers including Trig are interpreting that clause.

How do you as an installer propose to meet 14 CFR § 91.227 (d)(1)?

This is something the FAA clearly cared about as RTCA DO-260 (that defines 1090ES Out) actually intended light aircraft 1090ES Out to be able to stay in airborne mode while on the ground. The FAA deliberately changed that in these regulation, likely with concern about integration with ADSE-X and ASSC ground management systems. Which uh is really unlikely to be an issue with gliders.

The worse thing to do is to use the GPS air/ground determination mode in gliders that may fly in wave, or even strong headwind. Flying around spewing ground mode messages will eventually get you a letter from the FAA. How different traffic/collision avoidance systems behave when they see an erroneous ground mode targets is too complex to guess, but likely not good.

Not ever transmitting a ground mode message might well have no practical impact in typical glider operations. Few gliders are landing and taxing around SFO or JFK. But gliders do operate at some busy airports at times and you want to be careful of possible interactions with a variety of traffic systems in other aircraft. Some airports also have ADS-B coverage down to ground level and in those cases the FAA might followup up with any SIL=3 ADS-B Out systems that is not switching to ground mode. But not being a likely practical issue and not meeting regulation requirements are two separate things.

So it's *my recommendation* that 2020 Compliant ADS-B Out installations in all glider use a pitot squat switch.

If the glider is type certificated your A&P IA should follow the instructions in the TT22/TN70 STC. Not all of that STC is directly relevant to glider installs, but it does call out a the pitot squat switch (luckily it does not mandate the GPS air/ground mode determination).

If would hope A&Ps installing ADS-B out systems in experimental gliders are discussing how this works with owners, whether they are installing a pitot/squat switch or not, checking the operation of this systems (e.g. confirming the TT22 automatically display flips from ON to ALT as the glider takes off). and making sure the owner understand how to use whatever they have installed. FAA ADS-B Performance Reports will flag ground mode when airborne errors and airborne mode when on ground errors (although in many cases the FAA receiver towers will will not see your aircraft on the ground). If you install any of this stuff and it routinely has problems, expect the FAA to eventually followup with you.

If you are doing this yourself.... how do you propose to meet 14 CFR § 91.227 (d)(1)? What will the the person who signs off the glider's annual condition inspection expect to see for 91.227 compliance?

Squat switches are really a subtler things here, so many ADS-B Out installations have other more fundamental problems because A&Ps or owners doing work are not being careful with basic software setup. That can include not working at all, working, but not well enough to be seen by ATC, etc. You have to test each install by pulling an FAA Public Performance Report. The TT22 just saying it has a position fix is not enough to know things are working OK. I hope A&Ps are requiring owners to do an ADS-B Out test flight of all experimental gliders they work on, even if not called out in FAA policy (like it is for type certified aircraft). The FAA ADS-B Out Public Performance Report has been updated to request the submitter asking for the report to note who did the installation. The FAA seem to be exceedingly helpful with ADS-B Out problems, but pay attention.

TABS/TSO-C199 specifically allows the aircraft to stay in airborne mode on the ground. So for a TABS install I would argue the best thing to do is can just leave the pitot switch set to "none" and let the pilot manually select ALT. TABS also broadcast at a lower SIL level and not visible to ATC and not intended to interact the same with things like ADSE-X and ASSC.

[Charles Longley]

OK so I fly a glider which has nothing in it except a radio and basic instruments. I have an Oudie to keep me out of trouble. I just bought a FLARM brick with ADS-B in. Which I’ll install this winter. I’ll probably install a Trig Transponder next winter with ADS-B out. I’ve installed several different ADS-B out transponder systems in power airplanes.. I haven’t yet installed a squat switch in any of them. Generally power airplanes are faster than gliders. But there’s obviously Cub types that will fly at glider speeds so why don’t they have squat switches. I am just spit balling here. But it’s a good question.

[Darryl Ramm]

On Monday, November 25, 2019 at 10:22:16 PM UTC-8, Charles Longley wrote:
> OK so I fly a glider which has nothing in it except a radio and basic instruments. I have an Oudie to keep me out of trouble. I just bought a FLARM brick with ADS-B in. Which I’ll install this winter. I’ll probably install a Trig Transponder next winter with ADS-B out. I’ve installed several different ADS-B out transponder systems in power airplanes. I haven’t yet installed a squat switch in any of them. Generally power airplanes are faster than gliders. But there’s obviously Cub types that will fly at glider speeds so why don’t they have squat switches. I am just spit balling here. But it’s a good question.

Why don't you ask the person who did the installation in any "cub types" how they intended it to comply with 14 CFR § 91.227 (d)(1)? And what happens in strong headwinds like those giving near zero groundspeed? Ask them if they plan flying in those conditions.

The simple assumption many power installations will make is to use GPS based air/ground switching... and slow enough GA aircraft will have issues if they get into a strong enough headwind. But they likely do not fly often in those conditions or have never thought about it. We should be thinking about it in gliders as earlier ADS-B Out installations ran into immediate problems in wave.

Heck in strong wave locations towplanes may well run into this issue, so for those operators at places like Minden it might be a good idea in the towplane as well, what the FSDO wants for approval, if anything, if the STC says use GPS determination is up for discussion with them.

I tried to explain what I understand the regulations to say, and point out what folks operating in wave conditions want to avoid (GPS groundspeed switching saying you are on the ground when at altitude in wave). If it was not the apparent need for automatic switching we would likely be better off selecting "none" as a TT22 switch setting and just rely on the pilot switching the transponder manually between ON and ALT.

[[email protected]]

> But there’s obviously Cub types that will fly at glider speeds so why don’t they have squat switches.

Trying to apply logic here is risky, but maybe because the STC doesn't ask for it because the airplane is not intended to fly at zero groundspeed and so emitting ground mode while flying would be inadvertent.

If the glider is intended for wave and/or not experimental, then the STC would ask for the switch and zero groundspeed in the air would be expected. So being able to convince an investigator that you did a good faith effort in emitting the right signal "during the appropriate phase of flight" would lead one to the extra switch.

[Dan Marotta]

I've said this before concerning my ADS-B Out installation in my
Certificated Stemme:

I did the installation myself as told to the FAA on my Public
Performance Report.Â* One of the questions to answer was, "Who did the
installation?".Â* By stating that I did the installation, I then had to
identify the A&P IA who inspected the installation and signed it off.Â*
He provided me with a logbook sticker and a copy of the 337 he sent to
the feds to document the installation as having conformed to the STC.Â*
At the first opportunity I had a pitot/static check and a transponder
check performed.

I installed a pneumatic squat switch simply to ensure that I would never
report GND mode while in flight, even while flying backwards in wave.

I followed the STC installation instructions which left most of it up to
the installer for a glider.Â* For power planes the instructions are
specific about high vs low wing, antenna location, etc., but a glider
fuselage does not fit the mold.Â* I installed the antenna on an aluminum
shelf made by a local shop and mounted inside the engine bay, under the
fiberglass turtle deck.Â* I installed the TN70 behind the panel and had
to modify the prefab cable since it powered the TN70 from the TT22 and
the STC specifically stated to power the TN70 through a separate circuit
breaker.Â* I thought the price of the pneumatic switch was outrageous but
since it's a Certificated aircraft, I paid the price.Â* You can get a
switch for considerably less for an Experimental ship.

The most difficult part of the setup was converting metric to real
measurements and back (sorry, couldn't help it:-D).

On 11/25/2019 11:06 PM, Darryl Ramm wrote:
> On Monday, November 25, 2019 at 8:39:51 PM UTC-8, wrote:
>> On Sunday, November 24, 2019 at 4:51:37 PM UTC-8, wrote:
>>> On Sunday, November 24, 2019 at 10:56:03 AM UTC-5, Dave Nadler wrote:
>>>> On Friday, November 22, 2019 at 3:01:42 PM UTC-5, wrote:
>>>>> I have heard gossip of ... leak issues.
>>>> Cure for squat leaks: https://tinyurl.com/ycvg3to4
>>> Well, that depends.
>> Can someone point me to the regulation that requires an experimental glider to install a squat switch along with adsb?
> There is no regulation that says that. Nobody here (including me) has ever claimed there is AFAIK.
>
> The relevant bit is hidden in 14 CFR 91.227 (d)(1)
>
> ...Minimum Broadcast Message Element Set for ADS-B Out. Each aircraft must broadcast the following information, as defined in TSO-C166b or TSO-C154c.....
>
> (1) The length and width of the aircraft;
>
> Length and Width of the aircraft are only transmitted in ground mode messages. So this regulation says for 2020 Compliance the system must be capable of switching to ground mode. But I (and others) interpret the intro wording "each aircraft must..." as a direction that this change must be automatic. It's not saying each aircraft must be capable of being put in air/ground mode by a pilot. It's saying the aircraft must... Now it's sure not very well worded but that requirement is how manufacturers including Trig are interpreting that clause.
>
> How do you as an installer propose to meet 14 CFR § 91.227 (d)(1)?
>
> This is something the FAA clearly cared about as RTCA DO-260 (that defines 1090ES Out) actually intended light aircraft 1090ES Out to be able to stay in airborne mode while on the ground. The FAA deliberately changed that in these regulation, likely with concern about integration with ADSE-X and ASSC ground management systems. Which uh is really unlikely to be an issue with gliders.
>
> The worse thing to do is to use the GPS air/ground determination mode in gliders that may fly in wave, or even strong headwind. Flying around spewing ground mode messages will eventually get you a letter from the FAA. How different traffic/collision avoidance systems behave when they see an erroneous ground mode targets is too complex to guess, but likely not good.
>
> Not ever transmitting a ground mode message might well have no practical impact in typical glider operations. Few gliders are landing and taxing around SFO or JFK. But gliders do operate at some busy airports at times and you want to be careful of possible interactions with a variety of traffic systems in other aircraft. Some airports also have ADS-B coverage down to ground level and in those cases the FAA might followup up with any SIL=3 ADS-B Out systems that is not switching to ground mode. But not being a likely practical issue and not meeting regulation requirements are two separate things.
>
> So it's *my recommendation* that 2020 Compliant ADS-B Out installations in all glider use a pitot squat switch.
>
> If the glider is type certificated your A&P IA should follow the instructions in the TT22/TN70 STC. Not all of that STC is directly relevant to glider installs, but it does call out a the pitot squat switch (luckily it does not mandate the GPS air/ground mode determination).
>
> If would hope A&Ps installing ADS-B out systems in experimental gliders are discussing how this works with owners, whether they are installing a pitot/squat switch or not, checking the operation of this systems (e.g. confirming the TT22 automatically display flips from ON to ALT as the glider takes off). and making sure the owner understand how to use whatever they have installed. FAA ADS-B Performance Reports will flag ground mode when airborne errors and airborne mode when on ground errors (although in many cases the FAA receiver towers will will not see your aircraft on the ground). If you install any of this stuff and it routinely has problems, expect the FAA to eventually followup with you.
>
> If you are doing this yourself.... how do you propose to meet 14 CFR § 91.227 (d)(1)? What will the the person who signs off the glider's annual condition inspection expect to see for 91.227 compliance?
>
> Squat switches are really a subtler things here, so many ADS-B Out installations have other more fundamental problems because A&Ps or owners doing work are not being careful with basic software setup. That can include not working at all, working, but not well enough to be seen by ATC, etc. You have to test each install by pulling an FAA Public Performance Report. The TT22 just saying it has a position fix is not enough to know things are working OK. I hope A&Ps are requiring owners to do an ADS-B Out test flight of all experimental gliders they work on, even if not called out in FAA policy (like it is for type certified aircraft). The FAA ADS-B Out Public Performance Report has been updated to request the submitter asking for the report to note who did the installation. The FAA seem to be exceedingly helpful with ADS-B Out problems, but pay attention.
>
> TABS/TSO-C199 specifically allows the aircraft to stay in airborne mode on the ground. So for a TABS install I would argue the best thing to do is can just leave the pitot switch set to "none" and let the pilot manually select ALT. TABS also broadcast at a lower SIL level and not visible to ATC and not intended to interact the same with things like ADSE-X and ASSC.
>
>
>
>
>
>
>
>
>
>
>
>

--
Dan, 5J

[[email protected]]

The STC approved Peregrine squat switch required for use with the Trig TN70 is $125.00 from Aircraft Spruce & Specialty. https://www.aircraftspruce.com/catalog/avpages/switchkit10-05913.php

It has been mentioned a cheaper pneumatic squat switch could be used if intended for an experimental glider running the TT22/TN72 combo.

Please identify suitable "experimental" pneumatic squat switches.

Thanks.

[Richard Pfiffner[_2_]]

On Tuesday, November 26, 2019 at 12:01:59 PM UTC-8, wrote:
> The STC approved Peregrine squat switch required for use with the Trig TN70 is $125.00 from Aircraft Spruce & Specialty. https://www.aircraftspruce.com/catalog/avpages/switchkit10-05913.php
>
> It has been mentioned a cheaper pneumatic squat switch could be used if intended for an experimental glider running the TT22/TN72 combo.
>
> Please identify suitable "experimental" pneumatic squat switches.
>
> Thanks.

http://www.craggyaero.com/transponder.htm


To confirm correct operation while sitting on ground, turn the transponder mode knob to alt and the display should say grd, then you can increase pitot pressure to above the stall speed setting and the transponder display will switch to alt.

If you fly in wave without this switch your ground speed may be very low and ATC will think you are on the ground.

AIR PRESSURE SWITCH/Normally open, 42 knots, adjustable.

$48.50

Richard
www.craggyaero.com

[[email protected]]

On Monday, November 25, 2019 at 10:06:27 PM UTC-8, Darryl Ramm wrote:

"....the system must be capable of switching to ground mode".

Hi Darryl, thanks for providing the relevant regulation. I find it very unclear, but now at least I know the regulation behind this discussion. Personally, I would say that since my glider can't fly without me in the cockpit, I am an essential part of the system, and as such, I will manually turn the adsb system off when I'm on the ground. So I'm doing that in my experimental glider, with my self-installed TT22/TN72. My installation has passed the airborne adsb check that ATC provides, and I showed that report on my last condition inspection, although I was not asked to. I did also buy a squat switch on ebay for $12, but decided not to install it, since I worried that a small leak would upset my flight computer, which is vital when flying here in the west.

[Tom BravoMike]

On Tuesday, November 26, 2019 at 2:50:19 PM UTC-6, Richard Pfiffner wrote:
> On Tuesday, November 26, 2019 at 12:01:59 PM UTC-8, wrote:
> > The STC approved Peregrine squat switch required for use with the Trig TN70 is $125.00 from Aircraft Spruce & Specialty. https://www.aircraftspruce.com/catalog/avpages/switchkit10-05913.php
> >
> > It has been mentioned a cheaper pneumatic squat switch could be used if intended for an experimental glider running the TT22/TN72 combo.
> >
> > Please identify suitable "experimental" pneumatic squat switches.
> >
> > Thanks.
>
> http://www.craggyaero.com/transponder.htm
>
>
> To confirm correct operation while sitting on ground, turn the transponder mode knob to alt and the display should say grd, then you can increase pitot pressure to above the stall speed setting and the transponder display will switch to alt.
>
> If you fly in wave without this switch your ground speed may be very low and ATC will think you are on the ground.
>
> AIR PRESSURE SWITCH/Normally open, 42 knots, adjustable.
>
> $48.50
>
> Richard
> www.craggyaero.com

My glider can fly slower than 42 kts airspeed with flaps. What then? Can that be adjusted? How is it done?

[Richard Pfiffner[_2_]]

On Tuesday, November 26, 2019 at 2:06:19 PM UTC-8, Tom BravoMike wrote:
> On Tuesday, November 26, 2019 at 2:50:19 PM UTC-6, Richard Pfiffner wrote:
> > On Tuesday, November 26, 2019 at 12:01:59 PM UTC-8, wrote:
> > > The STC approved Peregrine squat switch required for use with the Trig TN70 is $125.00 from Aircraft Spruce & Specialty. https://www.aircraftspruce.com/catalog/avpages/switchkit10-05913.php
> > >
> > > It has been mentioned a cheaper pneumatic squat switch could be used if intended for an experimental glider running the TT22/TN72 combo.
> > >
> > > Please identify suitable "experimental" pneumatic squat switches.
> > >
> > > Thanks.
> >
> > http://www.craggyaero.com/transponder.htm
> >
> >
> > To confirm correct operation while sitting on ground, turn the transponder mode knob to alt and the display should say grd, then you can increase pitot pressure to above the stall speed setting and the transponder display will switch to alt.
> >
> > If you fly in wave without this switch your ground speed may be very low and ATC will think you are on the ground.
> >
> > AIR PRESSURE SWITCH/Normally open, 42 knots, adjustable.
> >
> > $48.50
> >
> > Richard
> > www.craggyaero.com
>
> My glider can fly slower than 42 kts airspeed with flaps. What then? Can that be adjusted? How is it done?

This switch says 34 Kts.

http://www.craggyaero.com/Trig/Airspeedswitch.pdf

The less expensive switch on this page

http://www.craggyaero.com/transponder.htm

MLP503 I tested at 28 KTS

Richard
www.craggyaero.com

[Richard Pfiffner[_2_]]

On Tuesday, November 26, 2019 at 2:06:19 PM UTC-8, Tom BravoMike wrote:
> On Tuesday, November 26, 2019 at 2:50:19 PM UTC-6, Richard Pfiffner wrote:
> > On Tuesday, November 26, 2019 at 12:01:59 PM UTC-8, wrote:
> > > The STC approved Peregrine squat switch required for use with the Trig TN70 is $125.00 from Aircraft Spruce & Specialty. https://www.aircraftspruce.com/catalog/avpages/switchkit10-05913.php
> > >
> > > It has been mentioned a cheaper pneumatic squat switch could be used if intended for an experimental glider running the TT22/TN72 combo.
> > >
> > > Please identify suitable "experimental" pneumatic squat switches.
> > >
> > > Thanks.
> >
> > http://www.craggyaero.com/transponder.htm
> >
> >
> > To confirm correct operation while sitting on ground, turn the transponder mode knob to alt and the display should say grd, then you can increase pitot pressure to above the stall speed setting and the transponder display will switch to alt.
> >
> > If you fly in wave without this switch your ground speed may be very low and ATC will think you are on the ground.
> >
> > AIR PRESSURE SWITCH/Normally open, 42 knots, adjustable.
> >
> > $48.50
> >
> > Richard
> > www.craggyaero.com
>
> My glider can fly slower than 42 kts airspeed with flaps. What then? Can that be adjusted? How is it done?

Adjusted with a screw on the switch.

Richard
www.craggyaero.com

[Charles Longley]

I am not 100% sure a squat switch is needed in a glider. Here’s a quote from Garmin through an AOPA article-
For aircraft without retractable gear aircraft, Garmin ADS-B equipment analyzes various data available to the system for air/ground determination. This includes groundspeed; vertical rate; airspeed; radar altimeter, if available; a rotorcraft’s collective position, if available; comparison of aircraft altitude to nearby airport elevation, if available; and comparison of groundspeed and/or airspeed to aircraft stall speed, Garmin’s Stone said.

Trig is the preferred transponder for gliders due to size. Does anyone know if a Trig transponder analyzes data like Garmin equipment?

[Charles Longley]

To answer the original poster. When something is changed or added to a pitot/static system the A&P or Repairman is required to do a leak check.

[Charles Longley]

Ha answered my own question through a little research! Trig recommends an airspeed switch- https://www.trig-avionics.com/library/TN72%20Glider%20installation%20-%20ADS-B%20guidance%20slides%20-%20August%202018.pdf
I’ll have to give it some thought before I install one.

[Darryl Ramm]

On Wednesday, November 27, 2019 at 10:59:06 PM UTC-8, Charles Longley wrote:
> I am not 100% sure a squat switch is needed in a glider. Here’s a quote from Garmin through an AOPA article-
> For aircraft without retractable gear aircraft, Garmin ADS-B equipment analyzes various data available to the system for air/ground determination. This includes groundspeed; vertical rate; airspeed; radar altimeter, if available; a rotorcraft’s collective position, if available; comparison of aircraft altitude to nearby airport elevation, if available; and comparison of groundspeed and/or airspeed to aircraft stall speed, Garmin’s Stone said.
>
> Trig is the preferred transponder for gliders due to size. Does anyone know if a Trig transponder analyzes data like Garmin equipment?

Uh yes, that's the "GPS" setting under "Select Squat Switch type".

You keep making statements about stuff or asking questions about about things that is already well settled and has been mentioned here many times.

This is years old information. I identified this GPS groundspeed determination in Trig Transponders as a problem in early glider installs. I let Trig know about that. I've described it all over r.a.s. I mentioned at it at an SSA convention talk. I've worked with every Trig glider dealer in the USA to let them know about it and to get squat pitot switches available. And when Trig updated the GPS algorithm recently I checked with them and they continued to state that this GPS based algorithm was *not* intended for use in glides or other aircraft that could have vey low (or negative) ground speed.. And I posted that on r.a.s. as well.

The very worse thing you can do for a glider that will fly in wave is to use GPS based determination.. It very likely will fail. For 2020 Compliance if 91.227 did not imply that automatic switching was required people would likely be better off with manual switching. For TABS installs just leave it manual. I don't know how many times I have posted this on r.a.s.

Garmin GPS based algorithm will likely fail in similar situations, you can ask Garmin what they are.

[Charles Longley]

So you’re the RAS police Darryl?

[Darryl Ramm]

On Thursday, November 28, 2019 at 10:42:19 AM UTC-8, Charles Longley wrote:
> So you’re the RAS police Darryl?

No, but when people keep posting confused/wrong stuff here, especially where it has the ability to affect safety, I will keep correcting them. Sadly I did not see your update before you posted, or I would not have said anything. Since you are an A&P IA I expect people in this community to believe you will get stuff right. And unfortunately amongst the useful stuff you post there are some posts from you about UAT Out use in towplanes (with no warnings about compatibility issues), this stuff, etc. many of which would be answered or clarified to you if you searched this forum for past threads. Other discussion on the pitot switches were posted in another r.a.s. thread just days, including where I quoted Trig on the updated GPS firmware not being intended for gliders with possible low/negative ground speed.

[Charles Longley]

So if you followed what I said you would see I was asking a question. I am not overly familiar with the Trig product line. But I am liking what I am seeing.

I disagree with your statement about the Garmin products. But it’s a moot point since it’s not an appropriate product for gliders.

What I don’t like is when someone asks a question you loudly proclaim, “We’ve talked about this before!� Well if you want to say anything at all why don’t you calmly point out the pertinent conversation? Our how the original poster asked about pitot/static leaks when you install a squat switch. You could have pointed out that a pitot/static check with a calibrated tester is required when installing it.

Happy Thanksgiving by the way! I am off to stuff my face.

[Dan Marotta]

It's not that expensive and the installation is trivial.Â* Why the concern?

On 11/28/2019 10:11 AM, Charles Longley wrote:
> Ha answered my own question through a little research! Trig recommends an airspeed switch- https://www.trig-avionics.com/library/TN72%20Glider%20installation%20-%20ADS-B%20guidance%20slides%20-%20August%202018.pdf
> I’ll have to give it some thought before I install one.

--
Dan, 5J

[Charles Longley]

I am thinking about a better mousetrap. Probably can’t do a squat switch on the gear because of the configuration on the ASW20. But I’ll think it over.

[Scott Williams[_2_]]

On Thursday, November 28, 2019 at 5:30:34 PM UTC-6, Charles Longley wrote:
> I am thinking about a better mousetrap. Probably can’t do a squat switch on the gear because of the configuration on the ASW20. But I’ll think it over.

Just an observation, but a true "squat" switch senses the gear bearing the weight of the airframe on the ground. Not just whether the gear is extended or retracted.
another can of worms is documenting such a switch install.

just two cents worth of clarification.
best wishes,
Scott

[Dan Marotta]

Everything I've flown with a squat switch (props, turboprops, jets) has
had shock struts.Â* Does the '20 have one of those?

Come to think of it, we use "landing gear down and locked" as a position
for a micro switch in our gear warning systems.Â* It shouldn't be at all
difficult to use a micro switch in the "landing gear up and locked"
position as your "in flight" sensor.Â* But when you lower the gear,
you'll be reporting "on ground".Â* You could also use a toggle switch,
just don't forget to flip it.Â* Or you could simply switch your
transponder from ON to ALT before takeoff and after landing.

On 11/28/2019 4:30 PM, Charles Longley wrote:
> I am thinking about a better mousetrap. Probably can’t do a squat switch on the gear because of the configuration on the ASW20. But I’ll think it over.

--
Dan, 5J

[Charles Longley]

Yeah I am familiar with how a squat switch works. There’s no suspension in an ASW-20 except the tire so no place to put the squat switch. I’ll take a look at it when I do the Condition Inspection. Maybe something will come to me.

[[email protected]]

On Friday, November 29, 2019 at 5:58:13 PM UTC-8, Charles Longley wrote:
> Yeah I am familiar with how a squat switch works. There’s no suspension in an ASW-20 except the tire so no place to put the squat switch. I’ll take a look at it when I do the Condition Inspection. Maybe something will come to me.

Can anyone show me the FAA regulation that requires a squat switch in a glider?

[Charles Longley]

There’s no requirement. The issue is if you get down to a low ground speed in flight the transponder might go into the ground mode. I think it’s getting a little overblown on RAS. Trig recommends a squat switch to compensate for it. Some of the other transponder manufactures can compensate for it by programming. I haven’t put a squat switch in any of the power airplanes I’ve installed ADS-B transponders in.

[Darryl Ramm]

On Friday, November 29, 2019 at 9:25:29 PM UTC-8, Charles Longley wrote:
> There’s no requirement.

No requirement for a squat switch explicitly, but there is a (not very clear) requirement for some form of automatic air/ground switching for 2020 compliance and you should want to use something that uh actually works reliably. See my tenth post in this thread.

>The issue is if you get down to a low ground speed in flight the transponder might go into the ground mode. I think it’s getting a little overblown on RAS. Trig recommends a squat switch to compensate for it. Some of the other transponder manufactures can compensate for it by programming. I haven’t put a squat switch in any of the power airplanes I’ve installed ADS-B transponders in.

Oh Jesus, yes but none of the aircraft you have installed ADS-B out in are gliders that fly in mountain wave. Nothing of what you have done in those power aircraft installs is relevant here.

The other transponder manufactures do not just "compensate for this by programming". I've got a pretty good understanding of GPS technology and I have no clue how this would be possible. You have no way of knowing that Garmin or other systems that use GPS detected ground speed to switch from air/ground will work in scenarios where those aircraft have near zero groundspeed without problems. A GPS in a glider or any other aircraft hovering in strong enough wave with a near zero ground speed just can't work out if it is on the ground or not. That you don't read about this in Garmin or other install documentation is likely only because those aircraft don't fly in strong enough wave/headwinds to have this problem.

Again we known for several years now this is a problem for gliders in mountain wave. Especially if your glider is going to fly in wave or strong headwinds please pay attention and get this right with a pneumatic pitot switch. Personally I'd install it that way in every glider, because you just don't know where it will end up flying.

Again if you are installing TABS just set the transponder squat switch to "None" and use manual ON/ALT switching on the transponder.

The very worse thing you can do in a glider that has any chance of being in mountain wave or a strong headwind is select GPS based air/ground switching.

If 91.227 did not imply automatic switching was required you would be better off choosing none and just relying on the ON/ALT switch on the transponder.

[Darryl Ramm]

On Friday, November 29, 2019 at 8:45:37 PM UTC-8, wrote:
> On Friday, November 29, 2019 at 5:58:13 PM UTC-8, Charles Longley wrote:
> > Yeah I am familiar with how a squat switch works. There’s no suspension in an ASW-20 except the tire so no place to put the squat switch. I’ll take a look at it when I do the Condition Inspection. Maybe something will come to me.
>
> Can anyone show me the FAA regulation that requires a squat switch in a glider?

You are repeating yourself. I answered this same question from you in the tenth post of this thread. Have regulations change since then?

You may not agree with the reasoning there, I think it's *awfully* written FWTW, but I'm pointing out this is the interpretation used in the avionics industry. I also think it was an bad idea for the FAA to require this for light aircraft and I wish they had left that with the RTCA DO-260 standard of not requiring light aircraft to transmit in ground mode at all (continue transmitting ADS-B airborne messages on on the ground).

[Eric Greenwell[_4_]]

Darryl Ramm wrote on 11/29/2019 10:36 PM:
> Again if you are installing TABS just set the transponder squat switch to "None" and use manual ON/ALT switching on the transponder.

I might forget to switch it correctly. Would using the "gear is down" switch to
change between ground/airborne be a sensible choice? The pattern (and the first
500'-1000' after the takeoff) would be flown showing the glider was on the ground,
of course, but that might be better than having the whole flight showing as on the
ground.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[[email protected]]

https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==

[Eric Greenwell[_4_]]

wrote on 11/30/2019 7:45 AM:
> https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==
>
I don't think I'd hear it with the motor running. Maybe a towed glider solution?
And would an STC be needed? 303 form? Just a field signoff? Do it and don't say
anything? So many choices...

--

[Scott Williams[_2_]]

On Saturday, November 30, 2019 at 12:45:34 AM UTC-6, Darryl Ramm wrote:
> On Friday, November 29, 2019 at 8:45:37 PM UTC-8, wrote:
> > On Friday, November 29, 2019 at 5:58:13 PM UTC-8, Charles Longley wrote:
> > > Yeah I am familiar with how a squat switch works. There’s no suspension in an ASW-20 except the tire so no place to put the squat switch.. I’ll take a look at it when I do the Condition Inspection. Maybe something will come to me.
> >
> > Can anyone show me the FAA regulation that requires a squat switch in a glider?
>
> You are repeating yourself. I answered this same question from you in the tenth post of this thread. Have regulations change since then?
>
> You may not agree with the reasoning there, I think it's *awfully* written FWTW, but I'm pointing out this is the interpretation used in the avionics industry. I also think it was an bad idea for the FAA to require this for light aircraft and I wish they had left that with the RTCA DO-260 standard of not requiring light aircraft to transmit in ground mode at all (continue transmitting ADS-B airborne messages on on the ground).

Having had a trig 2020 compliant ADS-B out system installed in my Standard type certificated glider, I found the peregrine pneumatic switch elegant, compact, cheap, and reliable. not to mention readily available and acceptable to the documentation requirements.
I also understand the deep desire some have to 'invent a better mousetrap'
Good lift,
Scott

[Dan Marotta]

Great idea, Mark!Â* But you'll have to figure out how to connect them
electrically to the transponder.Â* I don't think the FAA will be able to
hear the scraping given the distance to most glider fields.Â* Then again,
those would make a great gear warning system!

BTW, I would have expected to find those in the JC Whitney catalog...

On 11/30/2019 8:45 AM, wrote:
> https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==
> <> https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==,,-- ,Dan, 5J>

<>
https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==,,--
,Dan, 5J>
--
Dan, 5J <>
https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==,,--
,Dan, 5J>

[Dave Nadler]

On Saturday, November 30, 2019 at 10:45:49 AM UTC-5, wrote:
> https://www.amazon.com/United-Pacific-Industries-70203-Chrome/dp/B007IWTTO6/ref=sr_1_1_sspa?crid=3AKQS0X748U22&keywords=curb+feelers&qid=1575128712&sprefix=curb+%2Caps%2C194&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1U1MVBMUFgwU1pBJ mVuY3J5cHRlZElkPUEwNDczMjQyMjBEMFVMREpCNFcxNSZlbmN yeXB0ZWRBZElkPUEwMzkwNTEyVE5HMDVPQU4ySFRaJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==

Best idea yet!!

[Charles Longley]

Actually out of curiosity I looked at the pin out diagram for a Garmin transponder. There’s no pin out for a squat switch. Guess they do air-ground logic through programming as quoted by AOPA. Too bad they don’t make a smaller transponder.

[Dan Marotta]

I'm pretty sure the Trig transponder allows the GND/ALT determination to
be made without use of a squat switch.

On 11/30/2019 1:21 PM, Charles Longley wrote:
> Actually out of curiosity I looked at the pin out diagram for a Garmin transponder. There’s no pin out for a squat switch. Guess they do air-ground logic through programming as quoted by AOPA. Too bad they don’t make a smaller transponder.

--
Dan, 5J

[Mike N.]

How is Trig determining ground / alt without a switch?

I'm planning on a manual switch. I'll just add setting it to alt in my pre-takeoff instrument set scan.

[[email protected]]

You can also get Fuzzy Dice and a Bobblehead Jesus to replace the slip/skid ball and G-meter. Just sayin'

[Dan Marotta]

It's been a while, but I believe Trig uses GPS ground speed to determine
flight status.Â* The concern is about gliders flying in wave and clocking
extremely low ground speed resulting in the transponder reporting the
glider on the ground.

On 11/30/2019 5:37 PM, Mike N. wrote:
> How is Trig determining ground / alt without a switch?
>
> I'm planning on a manual switch. I'll just add setting it to alt in my pre-takeoff instrument set scan.

--
Dan, 5J

[Scott Williams[_2_]]

On Saturday, November 30, 2019 at 6:47:48 PM UTC-6, Dan Marotta wrote:
> It's been a while, but I believe Trig uses GPS ground speed to determine
> flight status.Â* The concern is about gliders flying in wave and clocking
> extremely low ground speed resulting in the transponder reporting the
> glider on the ground.
>
> On 11/30/2019 5:37 PM, Mike N. wrote:
> > How is Trig determining ground / alt without a switch?
> >
> > I'm planning on a manual switch. I'll just add setting it to alt in my pre-takeoff instrument set scan.
>
> --
> Dan, 5J

the trig electrically allows gnd/alt determination several ways, not all are approved.
1. no determination
2. gps determination (problematic in wave for gliders)
3. manual switch using the "squat switch input"
4. pitot pressure squat switch from peregrine.
there may be other schemes, but these are some.

Scott

[Mike Schumann[_2_]]

On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell wrote:
> Darryl Ramm wrote on 11/29/2019 10:36 PM:
> > Again if you are installing TABS just set the transponder squat switch to "None" and use manual ON/ALT switching on the transponder.
>
> I might forget to switch it correctly. Would using the "gear is down" switch to
> change between ground/airborne be a sensible choice? The pattern (and the first
> 500'-1000' after the takeoff) would be flown showing the glider was on the ground,
> of course, but that might be better than having the whole flight showing as on the
> ground.
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

If you use a squat switch with a Trig transponder, I believe that also puts the Transponder into GRND mode, so it wouldn't be responding to interrogations. The one place you do want ADS-B OUT and your transponder operating is in the pattern. That's where half of the midairs occur. Turning off ADS-S B OUT or your transponder as soon as you lower the gear is a really bad idea.

[Darryl Ramm]

On Saturday, November 30, 2019 at 7:30:25 PM UTC-8, Mike Schumann wrote:
> On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell wrote:
> > Darryl Ramm wrote on 11/29/2019 10:36 PM:
> > > Again if you are installing TABS just set the transponder squat switch to "None" and use manual ON/ALT switching on the transponder.
> >
> > I might forget to switch it correctly. Would using the "gear is down" switch to
> > change between ground/airborne be a sensible choice? The pattern (and the first
> > 500'-1000' after the takeoff) would be flown showing the glider was on the ground,
> > of course, but that might be better than having the whole flight showing as on the
> > ground.
> >
> > --
> > Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> > - "A Guide to Self-Launching Sailplane Operation"
> > https://sites.google.com/site/motorgliders/publications/download-the-guide-1
>
> If you use a squat switch with a Trig transponder, I believe that also puts the Transponder into GRND mode, so it wouldn't be responding to interrogations. The one place you do want ADS-B OUT and your transponder operating is in the pattern. That's where half of the midairs occur. Turning off ADS-S B OUT or your transponder as soon as you lower the gear is a really bad idea.

Mike has an important point. Please do not dick around and end up disabling a safety system. If you are in the air the transponder needs to be in ALT mode.

What is actually going on is a bit more messy, but "not responding to interrogations" is a useful summary. In GND mode Mode-S transponders will actually reply to direct addressed Mode-S interrogations, and do some other things, but that a far from a necessary set for the transponder to operate normally (e.g. it can't be acquired as a target by SSR). It will keep transmitting ADS-B Out, but messages encode the glider is on the ground, and some message content changes slightly. How all different ADS-B receivers all respond to that is uh anybody's guess. I just have an image in my mind of somebody seeing a transponder reply LCD thingy blink when in GND mode at some time and say "ha see it's replying OK". Ah nope, it's replying to a small subset of stuff. Flying in GND mode is a bad idea.

[Eric Greenwell[_4_]]

Darryl Ramm wrote on 11/30/2019 10:13 PM:
> On Saturday, November 30, 2019 at 7:30:25 PM UTC-8, Mike Schumann wrote:
>> On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell wrote:
>>> Darryl Ramm wrote on 11/29/2019 10:36 PM:
>>>> Again if you are installing TABS just set the transponder squat switch to
>>>> "None" and use manual ON/ALT switching on the transponder.
>>>
>>> I might forget to switch it correctly. Would using the "gear is down"
>>> switch to change between ground/airborne be a sensible choice? The pattern
>>> (and the first 500'-1000' after the takeoff) would be flown showing the
>>> glider was on the ground, of course, but that might be better than having
>>> the whole flight showing as on the ground.
>>>
>
>>
>> If you use a squat switch with a Trig transponder, I believe that also puts
>> the Transponder into GRND mode, so it wouldn't be responding to
>> interrogations. The one place you do want ADS-B OUT and your transponder
>> operating is in the pattern. That's where half of the midairs occur.
>> Turning off ADS-S B OUT or your transponder as soon as you lower the gear is
>> a really bad idea.
>
> Mike has an important point. Please do not dick around and end up disabling a
> safety system. If you are in the air the transponder needs to be in ALT mode.
>
> What is actually going on is a bit more messy, but "not responding to
> interrogations" is a useful summary. In GND mode Mode-S transponders will
> actually reply to direct addressed Mode-S interrogations, and do some other
> things, but that a far from a necessary set for the transponder to operate
> normally (e.g. it can't be acquired as a target by SSR). It will keep
> transmitting ADS-B Out, but messages encode the glider is on the ground, and
> some message content changes slightly. How all different ADS-B receivers all
> respond to that is uh anybody's guess. I just have an image in my mind of
> somebody seeing a transponder reply LCD thingy blink when in GND mode at some
> time and say "ha see it's replying OK". Ah nope, it's replying to a small
> subset of stuff. Flying in GND mode is a bad idea.

I thought it might be a bad idea, but it was easy to do, so worth asking. When I
do a TABS install, I will use an airspeed sensor - easy and cheap enough.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Dan Marotta]

Since I started flying in 1973 REAL MEN (:-D) manually switched their
transponders from Off to STBY to ON, then from OFF to STBY to ON to ALT,
then from OFF to STBY to On to GND to ALT.Â* Now all you weenies need to
have a "system" to do it for you. Is the switch count too high?Â* I guess
the next thing you'll all need is instant coffee or beer in cans...

Happy December!Â* Winter is just three weeks away.

On 12/1/2019 7:54 AM, Eric Greenwell wrote:
> Darryl Ramm wrote on 11/30/2019 10:13 PM:
>> On Saturday, November 30, 2019 at 7:30:25 PM UTC-8, Mike Schumann wrote:
>>> On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell
>>> wrote:
>>>> Darryl Ramm wrote on 11/29/2019 10:36 PM:
>>>>> Again if you are installing TABS just set the transponder squat
>>>>> switch to
>>>>> "None" and use manual ON/ALT switching on the transponder.
>>>>
>>>> I might forget to switch it correctly. Would using the "gear is down"
>>>> switch to change between ground/airborne be a sensible choice? The
>>>> pattern
>>>> (and the first 500'-1000' after the takeoff) would be flown showing
>>>> the
>>>> glider was on the ground, of course, but that might be better than
>>>> having
>>>> the whole flight showing as on the ground.
>>>>
>>
>>>
>>> If you use a squat switch with a Trig transponder, I believe that
>>> also puts
>>> the Transponder into GRND mode, so it wouldn't be responding to
>>> interrogations.Â* The one place you do want ADS-B OUT and your
>>> transponder
>>> operating is in the pattern.Â* That's where half of the midairs occur.
>>> Turning off ADS-S B OUT or your transponder as soon as you lower the
>>> gear is
>>> a really bad idea.
>>
>> Mike has an important point. Please do not dick around and end up
>> disabling a
>> safety system. If you are in the air the transponder needs to be in
>> ALT mode.
>>
>> What is actually going on is a bit more messy, but "not responding to
>> interrogations" is a useful summary. In GND mode Mode-S transponders
>> will
>> actually reply to direct addressed Mode-S interrogations, and do some
>> other
>> things, but that a far from a necessary set for the transponder to
>> operate
>> normally (e.g. it can't be acquired as a target by SSR).Â* It will keep
>> transmitting ADS-B Out, but messages encode the glider is on the
>> ground, and
>> some message content changes slightly. How all different ADS-B
>> receivers all
>> respond to that is uh anybody's guess.Â* I just have an image in my
>> mind of
>> somebody seeing a transponder reply LCD thingy blink when in GND mode
>> at some
>> time and say "ha see it's replying OK". Ah nope, it's replying to a
>> small
>> subset of stuff. Flying in GND mode is a bad idea.
>
> I thought it might be a bad idea, but it was easy to do, so worth
> asking. When I do a TABS install, I will use an airspeed sensor - easy
> and cheap enough.
>

--
Dan, 5J

[Eric Greenwell[_4_]]

In 1973, I was such a real man, I didn't even HAVE a transponder! Now, I'm no
longer a "Real Man", I'm a "Real Old Man", and the less I have to remember, the
less I forget. Also, in 1973 I didn't have a flight computer, Flarm, inReach, or a
motor clogging my memory.

Also glad I don't have to remember to hook up the controls correctly - really glad
about that.

:^)

Dan Marotta wrote on 12/1/2019 7:50 AM:
> Since I started flying in 1973 REAL MEN (:-D) manually switched their transponders
> from Off to STBY to ON, then from OFF to STBY to ON to ALT, then from OFF to STBY
> to On to GND to ALT.* Now all you weenies need to have a "system" to do it for
> you. Is the switch count too high?* I guess the next thing you'll all need is
> instant coffee or beer in cans...
>
> Happy December!* Winter is just three weeks away.
>
>>> respond to that is uh anybody's guess.* I just have an image in my mind of
>>> somebody seeing a transponder reply LCD thingy blink when in GND mode at some
>>> time and say "ha see it's replying OK". Ah nope, it's replying to a small
>>> subset of stuff. Flying in GND mode is a bad idea.
>>
>> I thought it might be a bad idea, but it was easy to do, so worth asking. When I
>> do a TABS install, I will use an airspeed sensor - easy and cheap enough.
>>
>


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Jonathan St. Cloud]

On Sunday, December 1, 2019 at 7:51:01 AM UTC-8, Dan Marotta wrote:
> Since I started flying in 1973 REAL MEN (:-D) manually switched their
> transponders from Off to STBY to ON, then from OFF to STBY to ON to ALT,
> then from OFF to STBY to On to GND to ALT.Â* Now all you weenies need to
> have a "system" to do it for you. Is the switch count too high?Â* I guess
> the next thing you'll all need is instant coffee or beer in cans...
>
> Happy December!Â* Winter is just three weeks away.
>
> On 12/1/2019 7:54 AM, Eric Greenwell wrote:
> > Darryl Ramm wrote on 11/30/2019 10:13 PM:
> >> On Saturday, November 30, 2019 at 7:30:25 PM UTC-8, Mike Schumann wrote:
> >>> On Saturday, November 30, 2019 at 8:26:42 AM UTC-6, Eric Greenwell
> >>> wrote:
> >>>> Darryl Ramm wrote on 11/29/2019 10:36 PM:
> >>>>> Again if you are installing TABS just set the transponder squat
> >>>>> switch to
> >>>>> "None" and use manual ON/ALT switching on the transponder.
> >>>>
> >>>> I might forget to switch it correctly. Would using the "gear is down"
> >>>> switch to change between ground/airborne be a sensible choice? The
> >>>> pattern
> >>>> (and the first 500'-1000' after the takeoff) would be flown showing
> >>>> the
> >>>> glider was on the ground, of course, but that might be better than
> >>>> having
> >>>> the whole flight showing as on the ground.
> >>>>
> >>
> >>>
> >>> If you use a squat switch with a Trig transponder, I believe that
> >>> also puts
> >>> the Transponder into GRND mode, so it wouldn't be responding to
> >>> interrogations.Â* The one place you do want ADS-B OUT and your
> >>> transponder
> >>> operating is in the pattern.Â* That's where half of the midairs occur.
> >>> Turning off ADS-S B OUT or your transponder as soon as you lower the
> >>> gear is
> >>> a really bad idea.
> >>
> >> Mike has an important point. Please do not dick around and end up
> >> disabling a
> >> safety system. If you are in the air the transponder needs to be in
> >> ALT mode.
> >>
> >> What is actually going on is a bit more messy, but "not responding to
> >> interrogations" is a useful summary. In GND mode Mode-S transponders
> >> will
> >> actually reply to direct addressed Mode-S interrogations, and do some
> >> other
> >> things, but that a far from a necessary set for the transponder to
> >> operate
> >> normally (e.g. it can't be acquired as a target by SSR).Â* It will keep
> >> transmitting ADS-B Out, but messages encode the glider is on the
> >> ground, and
> >> some message content changes slightly. How all different ADS-B
> >> receivers all
> >> respond to that is uh anybody's guess.Â* I just have an image in my
> >> mind of
> >> somebody seeing a transponder reply LCD thingy blink when in GND mode
> >> at some
> >> time and say "ha see it's replying OK". Ah nope, it's replying to a
> >> small
> >> subset of stuff. Flying in GND mode is a bad idea.
> >
> > I thought it might be a bad idea, but it was easy to do, so worth
> > asking. When I do a TABS install, I will use an airspeed sensor - easy
> > and cheap enough.
> >
>
> --
> Dan, 5J

Let's have Boeing design a system to keep gliders from stalling too. I am with Dan on this one. For almost 7k hours I have been turning my transponder to alt before takeoff and turning to stby once clear of runway. Like I need something else in my life that can break. It is hard to break a habit, trust me from the bucket of bad habits.