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ADSB visibility with non certified GPS



 
 
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  #11  
Old September 22nd 17, 05:11 PM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default ADSB visibility with non certified GPS

This is very confusing.Â* So a TN72 is not a TSO device, but is compliant
and therefore can be mounted in an experimental aircraft which will be
seen by all compliant ADS-B In systems?Â* I feel cheated by having a
certificated aircraft!

On 9/21/2017 8:31 PM, Darryl Ramm wrote:
Walt, I think you are misunderstanding what Trig wrote. A TN72 GPS Source will be seen by everybody. That is why anybody doing ADS-B Out in an experimental glider with a TT22 should be equipping with at least a TN72 (or TN70, TN70 required for certified gliders).


--
Dan, 5J
  #12  
Old September 22nd 17, 05:22 PM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default ADSB visibility with non certified GPS

Looking into the TN70 a question comes to mind:Â* Can the GPS output be
split and used to feed the ClearNav, PowerFLARM, Dynon D10a, and
ClearNav Vario?Â* It seems such a shame to have FIVE GPS antennae on one
glider...Â* What about using one of those power splitters I've seen here
on RAS?

On 9/22/2017 10:06 AM, Dan Marotta wrote:
Jumping into the middle of this - what's the real reason to ignore an
ADS-B Out aircraft simply because the GPS source is "crappy"?Â* So what
if the position is off by 100 feet or so?Â* My PowerFLARM routinely
reports targets at 200 feet or more altitude difference, e.g., I may
get a report of a target 100 feet high and spot him a hundred feet or
so lower than I am.

It just seems ridiculous to ignore another aircraft which might be on
a collision course simply because his altitude or position may be
reported as a couple of hundred feet different from where he is.
That's what looking outside is for.Â* Following the same logic, of what
use is a non-TSO compliant GPS in an experimental aircraft if it will
be ignored by other aircraft?

Inquiring minds and all...Â* BTW, I plan on installing a TN70 to mate
with my TT22 in my certificated glider.

On 9/21/2017 7:41 PM, Darryl Ramm wrote:
On Thursday, September 21, 2017 at 6:20:54 PM UTC-7,
wrote:
What hasn't been discussed is how often non-approved ADSB out
sources are actually being ignored.

Ah I think we've been over what matters here many times, but it is a
mess.

100% of certified ADS-B in systems will ignore the ADS-B data from
100% of ADS-B Out systems that use a COTS/non-complaint GPS source
100% of the time.

So airliners, fast jets, regional jets, etc. which if they have ADS-B
In at all will be a certified In system, definitely won't see some
scabby ADS-B Out install using a COTS GPS source. Since many of those
aircraft today have TCAS II they will be see the transponder via TCAS
and be able to issue TCAS TA and RA fro that target. However the gap
in the middle is with many high-end GA aircraft that have certified
ADS-B In but no TCAS, they won't see a crappy COTS driven ADS-B Out.
But at the low-end GA market non-certified portable ADS-B In systems
will see those COTS powered targets. That is kinda brain dead but
it's how it is and easy to work around.. don't use a COTS GPS source....

With the relatively low price of theTN72, if owners want to equip an
experimental glider with ADS-B OutÂ* there is no excuse anymore for
using a COTS GPS source. I really don't want to get into how many GA
aircraft might or might not be affected, just do it properly and
install a TN72 or TN70 system. COTS GPS is just the wrong thing.



--
Dan, 5J
  #13  
Old September 22nd 17, 07:38 PM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADSB visibility with non certified GPS

On Friday, September 22, 2017 at 9:11:34 AM UTC-7, Dan Marotta wrote:
This is very confusing.Â* So a TN72 is not a TSO device, but is compliant
and therefore can be mounted in an experimental aircraft which will be
seen by all compliant ADS-B In systems?Â* I feel cheated by having a
certificated aircraft!

On 9/21/2017 8:31 PM, Darryl Ramm wrote:
Walt, I think you are misunderstanding what Trig wrote. A TN72 GPS Source will be seen by everybody. That is why anybody doing ADS-B Out in an experimental glider with a TT22 should be equipping with at least a TN72 (or TN70, TN70 required for certified gliders).


--
Dan, 5J


You, and everybody else will continue to be confused if you keep talking about "TSO" and not specifying what TSO you are talking about. This caused lot of unneeded confusion and many posts on r.a.s. when the TN72 was announced. I don't know how many times I;ve already pointed this out.

The TN72 is a TSO-C199 Class B (aka TABS GPS source) device. Which from a regulation point of view makes no difference, since there are no installation or usage regulations that cover TSO-C199 devices. But since it is TSO-C199 we know important things about it's GPS quality, SIL parsameters, etc. and how it will interact with IFR GPS receivers and ground infrastructure.

The TN72 is Not TSO-C145 (requited for ADS-B Out in certified aircraft)

The TN72 does not meet TSO-C145 requirements (so can't be used for ADS-B Out in experimental aircraft where you want to us it to meet 2020 carriage requirements, in the case of gliders can't be used to meet requirements in the few areas where exemptions don't cover).

---

But yes I agree on the "feeling cheated" part in general, it points out the regulations are kinda stupid, especially when applied to gliders.
  #14  
Old September 22nd 17, 07:48 PM posted to rec.aviation.soaring
John Carlyle
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Posts: 324
Default ADSB visibility with non certified GPS

Darryl,

You said "The TN72 does not meet TSO-C145 requirements (so can't be used for ADS-B Out in experimental aircraft where you want to use it to meet 2020 carriage requirements, in the case of gliders can't be used to meet requirements in the few areas where exemptions don't cover)."

For those of us who cannot keep up, would you kindly list the requirements where the exemptions don't cover?

Many thanks!
-John
  #15  
Old September 22nd 17, 08:01 PM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADSB visibility with non certified GPS

On Friday, September 22, 2017 at 11:48:33 AM UTC-7, John Carlyle wrote:
Darryl,

You said "The TN72 does not meet TSO-C145 requirements (so can't be used for ADS-B Out in experimental aircraft where you want to use it to meet 2020 carriage requirements, in the case of gliders can't be used to meet requirements in the few areas where exemptions don't cover)."

For those of us who cannot keep up, would you kindly list the requirements where the exemptions don't cover?

Many thanks!
-John


John

Start thinking more like a lawyer. Since gliders have broad ADS-B Out carriage exemptions in the areas those exemptions apply they remove the need for you to have ADS-B Out so by definition there is no requirements specific to *those areas* that apply.

The regulatory issue is if you have a certified aircraft, regardless of where you intend to or actually fly it the install and equipment has to meet 2020 carriage mandate requirements. That brings in the requirements for a TSO-C145 GPS source (e.g. a TN70 not TN72), and other things like excludes using a Trig TT-21.

Darryl
  #16  
Old September 22nd 17, 08:20 PM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADSB visibility with non certified GPS

On Friday, September 22, 2017 at 12:01:13 PM UTC-7, Darryl Ramm wrote:
On Friday, September 22, 2017 at 11:48:33 AM UTC-7, John Carlyle wrote:
Darryl,

You said "The TN72 does not meet TSO-C145 requirements (so can't be used for ADS-B Out in experimental aircraft where you want to use it to meet 2020 carriage requirements, in the case of gliders can't be used to meet requirements in the few areas where exemptions don't cover)."

For those of us who cannot keep up, would you kindly list the requirements where the exemptions don't cover?

Many thanks!
-John


John

Start thinking more like a lawyer. Since gliders have broad ADS-B Out carriage exemptions in the areas those exemptions apply they remove the need for you to have ADS-B Out so by definition there is no requirements specific to *those areas* that apply.

The regulatory issue is if you have a certified aircraft, regardless of where you intend to or actually fly it the install and equipment has to meet 2020 carriage mandate requirements. That brings in the requirements for a TSO-C145 GPS source (e.g. a TN70 not TN72), and other things like excludes using a Trig TT-21.

Darryl


14CFR 91.225 makes it mostly clear. Except I am hesitant to quote it again became it may yet again lead to lots of 10,000' confusion (just knock it off, gliders can operate above 10,000' without ADS-B Out).

But basically in a glider you can't fly without a compliant ADS-B out system in

Class B or C airspace, and

Anywhere below that top of Class B or Class C airspace or 10,000 feet MSL above that airspace, whichever is lower. Folks need to watch this, no clipping under or over (unless you are over 10,000' and above the airspace) corners of class B or C airspace.

This is the same as transponder requirements and you should really not be in those areas today without a transponder. Folks who fly gliders near controlled airspace should think about this.

And in all it's regulatory glory.... (yes OK gliders also need ADS-B Out in the Gulf of Mexico ADS-B surveillance area, if you out there in a sailplane you may have more problems than ADS-B Out compliance. But hey fly across the coastline in that area without a complaint ADS-B Out and you are violating 14CFR 91.225).


14CFR 91.225
....
(d) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in the following airspace unless the aircraft has equipment installed that meets the requirements in paragraph (b) of this section:

(1) Class B and Class C airspace areas;

(2) Except as provided for in paragraph (e) of this section, within 30 nautical miles of an airport listed in appendix D, section 1 to this part from the surface upward to 10,000 feet MSL;

(3) Above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL;

(4) Except as provided in paragraph (e) of this section, Class E airspace within the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and

(5) Class E airspace at and above 3,000 feet MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles.

(e) The requirements of paragraph (b) of this section do not apply to any aircraft that was not originally certificated with an electrical system, or that has not subsequently been certified with such a system installed, including balloons and gliders. These aircraft may conduct operations without ADS-B Out in the airspace specified in paragraphs (d)(2) and (d)(4) of this section. Operations authorized by this section must be conducted -

(1) Outside any Class B or Class C airspace area; and

(2) Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport, or 10,000 feet MSL, whichever is lower.
  #17  
Old September 22nd 17, 09:12 PM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADSB visibility with non certified GPS

Dan

The reason to ignore ADS-B traffic data from non-conforming aircraft is because thats what the standards say to do. I think this comes in via TSO-C195 and the RTCA standards it incorproates but I'm not going to spend time chasing this down now.

And if you are an RTCA committee member focused on airlines and government regulators and and avionics manufactures... and care about critical IFR spacing, ground surface spacing, etc. and know that COTS GPS errors can be way more than a few hundred feet at times... then surely you would argue that is reasonable. And from their view surely nobody is going to want to fly around transmitting ADS-B Out using a crappy COTS GPS that don't have trusted reliability ( e.g. like RAIM).

The eventual come back on this was.... the development of TSO-C199/TABS which is a middle ground that leverages COTS type technology internally. Unfortunately the FAA never closed the loop to allow TSO-C199 GPS sources for ADS-B Out in certified gliders.

I also don't want to think lots of aircraft could have random COTS GOPS connected to an ADS-B Out and be flying around close to dense traffic areas. It's all frustrating as well since all this is inherently insecure, with no encryption or authentication and bad actors could already do a lot of harm injecting fake traffic into the ADS-B system. This non-compliant ADS-B traffic display hurdle does nothing to stop that. Why the designers of ADS-B did not implement authentication, encryption and some form of useful security is beyond me. Oh well we need to keep the NAS primary radar systems around anyhow.... for when all this goes tits up.

It might be time to get used to what the airlines and high-end users want. With FAA privatization there may be much more of that....


On Friday, September 22, 2017 at 9:07:06 AM UTC-7, Dan Marotta wrote:
Jumping into the middle of this - what's the real reason to ignore an
ADS-B Out aircraft simply because the GPS source is "crappy"?Â* So what
if the position is off by 100 feet or so?Â* My PowerFLARM routinely
reports targets at 200 feet or more altitude difference, e.g., I may get
a report of a target 100 feet high and spot him a hundred feet or so
lower than I am.

It just seems ridiculous to ignore another aircraft which might be on a
collision course simply because his altitude or position may be reported
as a couple of hundred feet different from where he is. That's what
looking outside is for.Â* Following the same logic, of what use is a
non-TSO compliant GPS in an experimental aircraft if it will be ignored
by other aircraft?

Inquiring minds and all...Â* BTW, I plan on installing a TN70 to mate
with my TT22 in my certificated glider.

On 9/21/2017 7:41 PM, Darryl Ramm wrote:
On Thursday, September 21, 2017 at 6:20:54 PM UTC-7, wrote:
What hasn't been discussed is how often non-approved ADSB out sources are actually being ignored.

Ah I think we've been over what matters here many times, but it is a mess.

100% of certified ADS-B in systems will ignore the ADS-B data from 100% of ADS-B Out systems that use a COTS/non-complaint GPS source 100% of the time.

So airliners, fast jets, regional jets, etc. which if they have ADS-B In at all will be a certified In system, definitely won't see some scabby ADS-B Out install using a COTS GPS source. Since many of those aircraft today have TCAS II they will be see the transponder via TCAS and be able to issue TCAS TA and RA fro that target. However the gap in the middle is with many high-end GA aircraft that have certified ADS-B In but no TCAS, they won't see a crappy COTS driven ADS-B Out. But at the low-end GA market non-certified portable ADS-B In systems will see those COTS powered targets. That is kinda brain dead but it's how it is and easy to work around.. don't use a COTS GPS source....

With the relatively low price of theTN72, if owners want to equip an experimental glider with ADS-B Out there is no excuse anymore for using a COTS GPS source. I really don't want to get into how many GA aircraft might or might not be affected, just do it properly and install a TN72 or TN70 system. COTS GPS is just the wrong thing.


--
Dan, 5J

  #18  
Old September 22nd 17, 09:21 PM posted to rec.aviation.soaring
John Carlyle
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Posts: 324
Default ADSB visibility with non certified GPS

Oh, Darryl - think like a lawyer? Can't - I'm a physicist, legal thinking "does not compute".

Many thanks for explaining, and then explaining even more in subsequent posts. Me and my experimental glider are going with a Trig TT22 and a TN 72...

-John

On Friday, September 22, 2017 at 3:01:13 PM UTC-4, Darryl Ramm wrote:
John

Start thinking more like a lawyer. Since gliders have broad ADS-B Out carriage exemptions in the areas those exemptions apply they remove the need for you to have ADS-B Out so by definition there is no requirements specific to *those areas* that apply.

The regulatory issue is if you have a certified aircraft, regardless of where you intend to or actually fly it the install and equipment has to meet 2020 carriage mandate requirements. That brings in the requirements for a TSO-C145 GPS source (e.g. a TN70 not TN72), and other things like excludes using a Trig TT-21.

Darryl


  #19  
Old September 22nd 17, 09:30 PM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default ADSB visibility with non certified GPS

Thanks for your patience.

On 9/22/2017 12:38 PM, Darryl Ramm wrote:
On Friday, September 22, 2017 at 9:11:34 AM UTC-7, Dan Marotta wrote:
This is very confusing.Â* So a TN72 is not a TSO device, but is compliant
and therefore can be mounted in an experimental aircraft which will be
seen by all compliant ADS-B In systems?Â* I feel cheated by having a
certificated aircraft!

On 9/21/2017 8:31 PM, Darryl Ramm wrote:
Walt, I think you are misunderstanding what Trig wrote. A TN72 GPS Source will be seen by everybody. That is why anybody doing ADS-B Out in an experimental glider with a TT22 should be equipping with at least a TN72 (or TN70, TN70 required for certified gliders).

--
Dan, 5J

You, and everybody else will continue to be confused if you keep talking about "TSO" and not specifying what TSO you are talking about. This caused lot of unneeded confusion and many posts on r.a.s. when the TN72 was announced. I don't know how many times I;ve already pointed this out.

The TN72 is a TSO-C199 Class B (aka TABS GPS source) device. Which from a regulation point of view makes no difference, since there are no installation or usage regulations that cover TSO-C199 devices. But since it is TSO-C199 we know important things about it's GPS quality, SIL parsameters, etc. and how it will interact with IFR GPS receivers and ground infrastructure.

The TN72 is Not TSO-C145 (requited for ADS-B Out in certified aircraft)

The TN72 does not meet TSO-C145 requirements (so can't be used for ADS-B Out in experimental aircraft where you want to us it to meet 2020 carriage requirements, in the case of gliders can't be used to meet requirements in the few areas where exemptions don't cover).

---

But yes I agree on the "feeling cheated" part in general, it points out the regulations are kinda stupid, especially when applied to gliders.


--
Dan, 5J
  #20  
Old September 23rd 17, 12:30 AM posted to rec.aviation.soaring
son_of_flubber
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Posts: 1,550
Default ADSB visibility with non certified GPS

On Thursday, September 21, 2017 at 9:28:52 PM UTC-4, Darryl Ramm wrote:


Well the GPS sources are approved in they may meet say meet TSO-C145 or TSO-C199 or "meets requirements of TSO-C145", or maybe meet none of those of a COTS GPS etc. and that stuff is important to understand.

Trig is correct in what they say. Certified ADS-B In receivers and the ADS-B ground infrastructure will ignore all ADS-B out systems using COTS GPS. Airliners, fast jets, etc. not receiving any of that crap. (that does not stop TCAS seeing the aircraft via transponder interrogation).

The Trig TT22 with 1090ES Out driven by a TN72 GPS source, all properly installed, will be seen by all aircraft with 1090ES In, both portable and certified/fixed install systems. It will also be seen by all aircraft with UAT In if within ADS-R service coverage. However you can only install a TN72 in an experimental aircraft. Certified aircraft, including gliders, requires you use a TN70 as all ADS-B Out installs in certified aircraft must meet 2020 compliance requirements (which effectively require an actual TSO'ed TSO-C145 GPS source in a certified aircraft, including glider).

An ADS-B Out 2020 complaint install (which sticking with Trig, requires a TN70 not a TN72 GPS source) will be seen by all aircraft. Wether that is with a TSO-C145 GPS source (for certified aircraft), or a "meets performance requirements of a TSO-C145 source (an option for experimental aircraft)..... as long as they are all properly installed of course. trig foes not have a lower cost "non-TSO but meets performance requirements of TSO-C145 GPS source".

In an experimental aircraft not intended to fly where the 2020 carriage mandate applies (pop quiz: where do gliders need ADS-B out even with the carriage exemption? No it's not above 10.000') can install any GPS source as long as the ADS-B Out sets the correct quality parameters, and any old COTS GPS will require SIL=0 to be set which will guarantee that is ignored by aircraft with certified ADS-B In systems. It will still be seen by many portable ASD-B receivers, and certainly will be seen by PowerFLARM 1090ES In (assuming we are talking 1090ES Out).

The Trig TN72 is a TABS/TSO-C199 device, it is not TSO-C145, you can not install it in any certified aircraft (including gliders) and you can't use it to meet 2020 Carriage mandate requirements, but you can install it in an experimental aircraft for use outside ADS-B Out required carriage areas (including for gliders anywhere the 2020 carriage exemption lets you fly without compliant ADS-B out)...

And if your experimental glider is so equipped with a TN72 GPS source driving a Trig TT22 and it's properly installed then it *will* paint your glider on certified ADS-B In systems, both via direct 1090ES and via ADS-R for UAT In equipped aircraft. The TT22 importantly also ensures TCAS II systems can issue a RA (resolution advisory) against the glider, a pure UAT Out systems with no transponder cannot and will not cause TCAS to issue an RA. UAT Out equipped aircraft are also never visible to PowerFLARM (they can trigger PCAS if also transponder equipped), so for that reason avoid UAT Out use in gliders and towplanes.

A properly configured TT22 and TN72 GPS source will also trigger ADS-B ground services for your aircraft when in range of ADS-B ground stations (which won't help at all with PowerFLARM which can't decode any of those ground based services, to receive ADS-R, or TIS-B, or FIS-B ground services you also need a separate ADS-B In/non-PowerFLARM receiver as well as a suitable ADS-B Out system. And with reception on UAT to receive FIS-B).

---

On mixed installs with other potential ADS-B Out systems I would want to see the details of what exact ADS-B Out transponder is being used, but a TN72 in an experimental aircraft may well work with multiple different transponder options. TSO-C199 was intended to provide interoperability like that. And that will get you ground services and visibility on certified ADS-B In receivers. But be sure to ask the vendor if not Trig that they guarantee all that works... In practice the way to go today for ADS-B Out in gliders in the USA is to start with a Trig TT22 and use the TN-70 or TN72 and follow Trig's install documentation exactly.

---

Unfortunately Trig, who makes great stuff--their TT22 and associated GPS are great products, is saying some stuff that is a little sloppy again, their comment about triggering traffic services for gliders is made without the warning that a PowerFLARM can't receive those services. And they don't qualify TN72 is only for experimental gliders... I wish we had regulations that provided installs of that in certified gliders, as far as I understand we do not. I wish there were regulations (and maybe a STC) that allowed that. I'll talk to Trig and see if they can help be clearer here.



What changes in the above explanation if we substitute TT21 for TT22? I already have a TT21 installed in an Experimental glider.
 




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