Transponderz [Archive] - AviationBanter

jfitch

October 26th 12, 09:11 PM

On Friday, October 26, 2012 1:08:06 PM UTC-7, jfitch wrote:
> On Friday, October 26, 2012 9:33:49 AM UTC-7, 3Y wrote:
>
> > >
>
> >
>
> > > I put a Trig TT21 in last summer and have been happy with it. It's also compact and simple to install, I put an AAE L2 antenna in the nose which is also easy and seems to work fine. The customer service is also top notch.
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > > jim
>
> >
>
> >
>
> >
>
> > Jim or others,
>
> >
>
> >
>
> >
>
> > Does anyone know about any health risks by putting the antenna in close proximity to the pilot?
>
> >
>
> >
>
> >
>
> > Thanks, John
>
>
>
> This is covered in some depth by some papers published recently in Britain. The subject has to do with portable transponders for use in sport aviation there, these are handheld units which are expected in some cases to be carried in a pocket or worn on a harness. The conclusion of the tests was that as long as the antenna is farther than 8 or 10 inches, the hazard was acceptable by current occupational exposure rules, i.e., you would be allowed to experience that 8 hours a day.

I should add, I have an AEE dipole in the nose about 8 inches from my feet, but despite 200 watts tested radiated power from the Trig 21, it does not keep my feet warm... :)

October 26th 12, 10:49 PM

>
>
>
> I should add, I have an AEE dipole in the nose about 8 inches from my feet, but despite 200 watts tested radiated power from the Trig 21, it does not keep my feet warm... :)

Ive noticed a marked change in my sex drive with anything past 200 watts..;)
Seriously, to get back to the OP, I was thinking of a Trig for the ADS-b out capabilities and the PF for the ADS-B in. This way my set up will not become obsolete in a few years. Am I correct on this assumption?

Paul Remde

October 26th 12, 11:38 PM

Hi,

The bummer is that even though it is possible to connect a GPS up to the
Trig TT21 or TT22 an send ADS-B data out, the FAA says that is illegal.
They say you must use an approved GPS costing $3000+. I wish we could
convince the FAA that they are reducing safety dramatically by not allowing
any GPS to send data to the TT21/TT22.

Best Regards,

Paul Remde

"K" wrote in message
...

>
>
>
> I should add, I have an AEE dipole in the nose about 8 inches from my
> feet, but despite 200 watts tested radiated power from the Trig 21, it
> does not keep my feet warm... :)

Ive noticed a marked change in my sex drive with anything past 200 watts..;)
Seriously, to get back to the OP, I was thinking of a Trig for the ADS-b out
capabilities and the PF for the ADS-B in. This way my set up will not become
obsolete in a few years. Am I correct on this assumption?

son_of_flubber

October 27th 12, 04:05 AM

On Friday, October 26, 2012 6:39:14 PM UTC-4, Paul Remde wrote:

> The bummer is that even though it is possible to connect a GPS up to the
> Trig TT21 or TT22 an send ADS-B data out, the FAA says that is illegal.
> They say you must use an approved GPS costing $3000+.

A quick list of the approved GPS position sensors and prices

Freeflight 1201 WAAS/GPS Sensor $2,919.00
Freeflight 1204 WAAS/GPS Sensor $6,889.00

Could not find prices for the NexNav sensors:
NexNav MINI WAAS/GPS Sensor
NexNav MAX WAAS/GPS Sensor

Is NexNav shipping these products?

Maybe the price will come down when more than one vendor is shipping approved products.

Grider Pirate[_2_]

November 2nd 12, 03:36 PM

I cannot help cringing at the requirement for WAAS. If WAAS reduced
positional error to ZERO, that is still less than a 50 foot (15 meter)
improvement over non-differentially corrected GPS. If 50 feet is a
factor, they're screwing up.... big time. Does requiring a WAAS
capable GPS make sense to anyone? (aside from the FAA!)

On Oct 26, 8:05*pm, son_of_flubber > wrote:
> On Friday, October 26, 2012 6:39:14 PM UTC-4, Paul Remde wrote:
> > The bummer is that even though it is possible to connect a GPS up to the
> > Trig TT21 or TT22 an send ADS-B data out, the FAA says that is illegal.
> > They say you must use an approved GPS costing $3000+.
>
> A quick list of the approved GPS position sensors and prices
>
> Freeflight 1201 WAAS/GPS Sensor $2,919.00
> Freeflight 1204 WAAS/GPS Sensor $6,889.00
>
> Could not find prices for the NexNav sensors:
> NexNav MINI WAAS/GPS Sensor
> NexNav MAX WAAS/GPS Sensor
>
> Is NexNav shipping these products?
>
> Maybe the price will come down when more than one vendor is shipping approved products.

Mike C

November 2nd 12, 04:21 PM

What Paul said.

The reason I passed on mode S and bought mode C.

Mike

On Friday, October 26, 2012 4:39:14 PM UTC-6, Paul Remde wrote:
> Hi,
>
>
>
> The bummer is that even though it is possible to connect a GPS up to the
>
> Trig TT21 or TT22 an send ADS-B data out, the FAA says that is illegal.
>
> They say you must use an approved GPS costing $3000+. I wish we could
>
> convince the FAA that they are reducing safety dramatically by not allowing
>
> any GPS to send data to the TT21/TT22.
>
>
>
> Best Regards,
>
>
>
> Paul Remde
>
>
>
> "K" wrote in message
>
> ...
>
>
>
>
>
> >
>
> >
>
> >
>
> > I should add, I have an AEE dipole in the nose about 8 inches from my
>
> > feet, but despite 200 watts tested radiated power from the Trig 21, it
>
> > does not keep my feet warm... :)
>
>
>
> Ive noticed a marked change in my sex drive with anything past 200 watts..;)
>
> Seriously, to get back to the OP, I was thinking of a Trig for the ADS-b out
>
> capabilities and the PF for the ADS-B in. This way my set up will not become
>
> obsolete in a few years. Am I correct on this assumption?

Peter Purdie[_3_]

November 2nd 12, 04:28 PM

The factor you are missing is that approved Aviation GPS have an error
detection system, and send a message (which is included in the 1090ES data
out) to confirm the information is reliable. Low cost GPS doesn't.

In Europe, as I understand it, you can egally connect a low cost GPS to a
TT21 and it will be broadcast in the DS-B out, but including a 'do not rely
on this information' message. That's regardless of WAAS (or EGNOS over
here).

At 15:36 02 November 2012, Grider Pirate wrote:
>I cannot help cringing at the requirement for WAAS. If WAAS reduced
>positional error to ZERO, that is still less than a 50 foot (15 meter)
>improvement over non-differentially corrected GPS. If 50 feet is a
>factor, they're screwing up.... big time. Does requiring a WAAS
>capable GPS make sense to anyone? (aside from the FAA!)
>
>
>
>On Oct 26, 8:05=A0pm, son_of_flubber wrote:
>> On Friday, October 26, 2012 6:39:14 PM UTC-4, Paul Remde wrote:
>> > The bummer is that even though it is possible to connect a GPS up to
>th=
>e
>> > Trig TT21 or TT22 an send ADS-B data out, the FAA says that is
illegal.
>> > They say you must use an approved GPS costing $3000+.
>>
>> A quick list of the approved GPS position sensors and prices
>>
>> Freeflight 1201 WAAS/GPS Sensor $2,919.00
>> Freeflight 1204 WAAS/GPS Sensor $6,889.00
>>
>> Could not find prices for the NexNav sensors:
>> NexNav MINI WAAS/GPS Sensor
>> NexNav MAX WAAS/GPS Sensor
>>
>> Is NexNav shipping these products?
>>
>> Maybe the price will come down when more than one vendor is shipping
>appr=
>oved products.
>
>

Dave Nadler

November 2nd 12, 04:33 PM

Regardless of ADS-B out capability, you still want
a Mode S transponder, because:
- Mode S consumes less power
- Mode S will not cause a bunch of gliders in a thermal
to become invisible to a TCAS-equipped approaching jet,
as can happen with Mode A/C,
- Mode S can be "de-duplicated" by FLARM, as the transponder
will be identified as redundant with the more-accurate
FLARM information (other FLARM-equipped gliders will
be spared PCAS alarms from your transponder).

Please install Mode S, not Mode C.
You and everybody else will be a lot happier.

Hope that is clear,
Best Regards, Dave

Craig Funston[_2_]

November 2nd 12, 06:05 PM

On Friday, November 2, 2012 9:33:19 AM UTC-7, Dave Nadler wrote:
> Regardless of ADS-B out capability, you still want
>
> a Mode S transponder, because:
>
> - Mode S consumes less power
>
> - Mode S will not cause a bunch of gliders in a thermal
>
> to become invisible to a TCAS-equipped approaching jet,
>
> as can happen with Mode A/C,
>
> - Mode S can be "de-duplicated" by FLARM, as the transponder
>
> will be identified as redundant with the more-accurate
>
> FLARM information (other FLARM-equipped gliders will
>
> be spared PCAS alarms from your transponder).
>
>
>
> Please install Mode S, not Mode C.
>
> You and everybody else will be a lot happier.
>
>
>
> Hope that is clear,
>
> Best Regards, Dave

Dave,

I'm interested in more information regarding the rendering "invisible" potential of Mode A/C. I have a Terra Mode C available to me for the coming season & the research I did indicated to me that it is visible to TCAS equipped aircraft as long as the AD has been complied with. Is there something I missed in my research?

Thanks,
Craig

Dave Nadler

November 2nd 12, 06:11 PM

On Friday, November 2, 2012 2:05:34 PM UTC-4, Craig Funston wrote:

> Dave,
> I'm interested in more information regarding the rendering "invisible"
> potential of Mode A/C. I have a Terra Mode C available to me for the
> coming season & the research I did indicated to me that it is visible
> to TCAS equipped aircraft as long as the AD has been complied with.
> Is there something I missed in my research?
> Thanks,
> Craig

Yes, read especially the technical notes at the bottom of this page:
http://www.gliderpilot.org/FLARM-Transponders

For any new installation, get a Mode S unit !

Hope that helps,
Best Regards, Dave

Craig Funston[_2_]

November 2nd 12, 07:20 PM

On Friday, November 2, 2012 11:11:51 AM UTC-7, Dave Nadler wrote:
> On Friday, November 2, 2012 2:05:34 PM UTC-4, Craig Funston wrote:
>
>
>
> > Dave,
>
> > I'm interested in more information regarding the rendering "invisible"
>
> > potential of Mode A/C. I have a Terra Mode C available to me for the
>
> > coming season & the research I did indicated to me that it is visible
>
> > to TCAS equipped aircraft as long as the AD has been complied with.
>
> > Is there something I missed in my research?
>
> > Thanks,
>
> > Craig
>
>
>
> Yes, read especially the technical notes at the bottom of this page:
>
> http://www.gliderpilot.org/FLARM-Transponders
>
>
>
> For any new installation, get a Mode S unit !
>
>
>
> Hope that helps,
>
> Best Regards, Dave

Thanks Dave,

That provided the information I needed.

Craig

Tony[_5_]

November 2nd 12, 07:27 PM

On Friday, November 2, 2012 2:20:30 PM UTC-5, Craig Funston wrote:
> On Friday, November 2, 2012 11:11:51 AM UTC-7, Dave Nadler wrote: > On Friday, November 2, 2012 2:05:34 PM UTC-4, Craig Funston wrote: > > > > > Dave, > > > I'm interested in more information regarding the rendering "invisible" > > > potential of Mode A/C. I have a Terra Mode C available to me for the > > > coming season & the research I did indicated to me that it is visible > > > to TCAS equipped aircraft as long as the AD has been complied with. > > > Is there something I missed in my research? > > > Thanks, > > > Craig > > > > Yes, read especially the technical notes at the bottom of this page: > > http://www.gliderpilot.org/FLARM-Transponders > > > > For any new installation, get a Mode S unit ! > > > > Hope that helps, > > Best Regards, Dave Thanks Dave, That provided the information I needed. Craig

if you have the choice sure go with Mode S but if the choice is no transponder or mode c, go with mode c!

i happily installed a Microair mode c transponder in YYY this spring and it worked great all season.

Eric Greenwell[_4_]

November 2nd 12, 07:44 PM

On 11/2/2012 9:33 AM, Dave Nadler wrote:
> - Mode S will not cause a bunch of gliders in a thermal
> to become invisible to a TCAS-equipped approaching jet,
> as can happen with Mode A/C,

Even though the TCAS function doesn't work, is the approaching jet made
aware there are transponders at that 2-D position, altitude unknown?

What happens when the jet approaches a Mode A equipped aircraft? Is the
pilot made aware of it, even though the TCAS system cannot give him
climb/dive command?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Craig Funston[_2_]

November 2nd 12, 07:53 PM

On Friday, November 2, 2012 12:44:34 PM UTC-7, Eric Greenwell wrote:
> On 11/2/2012 9:33 AM, Dave Nadler wrote:
>
> > - Mode S will not cause a bunch of gliders in a thermal
>
> > to become invisible to a TCAS-equipped approaching jet,
>
> > as can happen with Mode A/C,
>
>
>
> Even though the TCAS function doesn't work, is the approaching jet made
>
> aware there are transponders at that 2-D position, altitude unknown?
>
>
>
> What happens when the jet approaches a Mode A equipped aircraft? Is the
>
> pilot made aware of it, even though the TCAS system cannot give him
>
> climb/dive command?
>
>
>
> --
>
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>
> email me)

Eric,

Not sure if you got a chance to read through the link Dave sent. Good information there. My take-away was that the gaggle problem is one of having multiple Mode C transponders in the same location. That's not a very likely scenario in the Columbia Basin where fly. I'm also not likely to be in controlled airspace so the high rate of interrogation responses isn't as big an issue. Mode C isn't my first choice, but given the choice between no transponder or Mode C in a relatively low traffic environment for the next couple years, I'll take the Mode C and save my pennies for a Trig. At least I'll be visible to jet traffic. I had a close encounter with an A6-E storming through my thermal last year that got my attention.

Craig

[email protected]

November 2nd 12, 08:06 PM

In equipment I fly (MD11 with TCAS II) I get azimuth and distance (estimated) with no altitude info. If I'm in Class A airspace, I don't worry about it a lot. Down low, I start looking.

On Friday, November 2, 2012 2:44:34 PM UTC-5, Eric Greenwell wrote:
> On 11/2/2012 9:33 AM, Dave Nadler wrote:
>
> > - Mode S will not cause a bunch of gliders in a thermal
>
> > to become invisible to a TCAS-equipped approaching jet,
>
> > as can happen with Mode A/C,
>
>
>
> Even though the TCAS function doesn't work, is the approaching jet made
>
> aware there are transponders at that 2-D position, altitude unknown?
>
>
>
> What happens when the jet approaches a Mode A equipped aircraft? Is the
>
> pilot made aware of it, even though the TCAS system cannot give him
>
> climb/dive command?
>
>
>
> --
>
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>
> email me)

Dave Nadler

November 2nd 12, 11:55 PM

For heavens sake Eric, please read the link.
Pay attention to "fruiting" and "multiple transponders
all transmitting at almost the same time, creating
noise like everybody talking at the same time,
unreadable by ATC or TCAS".

You know, kinda like RAS.

For this reason:
- aircraft in formation only have ONE aircraft's
transponder turned on
- aircraft approaching Oshkosh are required to turn
their transponders OFF (except Mode S)
- the rest of the world has effectively outlawed
Mode A/C in favor of Mode S.

Hope that's clear,
Best Regards, Dave

Mike C

November 3rd 12, 12:45 AM

On Nov 2, 5:55*pm, Dave Nadler > wrote:
> For heavens sake Eric, please read the link.
> Pay attention to "fruiting" and "multiple transponders
> all transmitting at almost the same time, creating
> noise like everybody talking at the same time,
> unreadable by ATC or TCAS".
>
> You know, kinda like RAS.
>
> For this reason:
> - aircraft in formation only have ONE aircraft's
> * transponder turned on
> - aircraft approaching Oshkosh are required to turn
> * their transponders OFF (except Mode S)
> - the rest of the world has effectively outlawed
> * Mode A/C in favor of Mode S.
>
> Hope that's clear,
> Best Regards, Dave

Dave,

I am wondering if using Oshkosh as an example applicable to a few
sailplanes, in a thermal, is not a bit of a strawman argument.

A separate point, it is my impression that traffic is so congested
there that the controllers are overwhelmed, not that the signals are
garbled and unreadable.

Mode S is superior being less of a load on our current system, but
still, Mode C is valid, safe and not the worthless tired technology
that it seems to be portrayed as.

Kind regards,

Mike

A few gliders in a thermal is not the Oshkosh scenario, where
controllers are overloaded with traffic and transponders are asked to
be turned off.

Darryl Ramm

November 3rd 12, 02:23 AM

On Friday, November 2, 2012 1:06:28 PM UTC-7, wrote:
> In equipment I fly (MD11 with TCAS II) I get azimuth and distance (estimated) with no altitude info. If I'm in Class A airspace, I don't worry about it a lot. Down low, I start looking.

What do you mean by "no altitude info". A TCAS II display is required to encode relative altitude information as a part of the traffic symbol "threat level" choice. And I think its required to have the relative altitude display numbers above/below the symbols. What system/version is in the MD-11?

And since "I get..." is ambiguous as to whether you mean you see on a display or whether the TCAS II system sees relative altitude. TCAS systems do see altitudes of all the nearby aircraft. Or they need to, if its a Mode C rich environment and they suffer from data collisions where the Mode C replies are not readable then the TCAS system quickly becomes useless for those threats (can't issue TA or RA and you may not see any azimuth). The good news is the quadrant antennas and hardware signal decorrelators (that can essentially untangle overlapping transponder transmissions) that TCAS II uses helps reduce problems with Mode-C garbling.

And to answer Eric's question, TCAS I and II would not see mode-A only transponders. They only issue Mode-C interrogations (well they do more for Mode S magic stuff but that does not change the discussion). Not interrogating Mode A helps cut down on wasting bandwidth/garbling and avoid possible Mode C/Mode A code aliasing problems. Anyhow nobody flies Mode-A only transponders anymore.

The bottom line for practical use is if you have Mode C transponder today there is nothing "wrong" with it, keep using it if you fly where transponders should be used. If you are purchasing a new transponder it makes no sense to purchase a Mode C unit today when there are great Mode S transponders available from folks like Trig.

But for ADS-B data-out futures... just don't hold your breath on the FAA making ADS-B data-out easy to install/affordable any time soon, even if you have a Trig transponder.

And if you fly near airliners and fast jets, from a technology viewpoint its not Flarm or ADS-B-data-in or even ADS-B data-out you want, its a Mode C or Mode S transponder that is seen by ATC radar and TCAS I and II. Know local traffic procedures, have your head on a swivel, and talk to ATC where possible/appropriate.

Darryl

Eric Greenwell[_4_]

November 3rd 12, 03:39 AM

On 11/2/2012 4:55 PM, Dave Nadler wrote:
>
> For heavens sake Eric, please read the link.
> Pay attention to "fruiting" and "multiple transponders
> all transmitting at almost the same time, creating
> noise like everybody talking at the same time,
> unreadable by ATC or TCAS".
>
> You know, kinda like RAS.
>
> For this reason:
> - aircraft in formation only have ONE aircraft's
> transponder turned on
> - aircraft approaching Oshkosh are required to turn
> their transponders OFF (except Mode S)
> - the rest of the world has effectively outlawed
> Mode A/C in favor of Mode S.
>
> Hope that's clear,
> Best Regards, Dave

Here's what the link says in #14: "A gaggle with multiple Mode C
transponders active may be invisible to TCAS collision avoidance,
because TCAS must receive ungarbled Mode C altitude replies to function."

It's not clear to me from that sentence that the gliders will be
completely invisible to the TCAS _system_, only that it's collision
avoidance functions won't work. Does the approaching, TCAS equipped
aircraft get _any_ indication there are aircraft with transponders in
that situation?

I understand TCAS will work much better if there is Mode C transponders
have some separation from each other. I'm just finding it hard to
understand that a TCAS system will be completely unaware of a bunch of
transponders, even if they are close together.

Does ATC see anything out there, even if the TCAS system can not?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

Darryl Ramm

November 3rd 12, 04:17 AM

On Friday, November 2, 2012 8:39:32 PM UTC-7, Eric Greenwell wrote:
> On 11/2/2012 4:55 PM, Dave Nadler wrote:
>
> >
>
> > For heavens sake Eric, please read the link.
>
> > Pay attention to "fruiting" and "multiple transponders
>
> > all transmitting at almost the same time, creating
>
> > noise like everybody talking at the same time,
>
> > unreadable by ATC or TCAS".
>
> >
>
> > You know, kinda like RAS.
>
> >
>
> > For this reason:
>
> > - aircraft in formation only have ONE aircraft's
>
> > transponder turned on
>
> > - aircraft approaching Oshkosh are required to turn
>
> > their transponders OFF (except Mode S)
>
> > - the rest of the world has effectively outlawed
>
> > Mode A/C in favor of Mode S.
>
> >
>
> > Hope that's clear,
>
> > Best Regards, Dave
>
>
>
> Here's what the link says in #14: "A gaggle with multiple Mode C
>
> transponders active may be invisible to TCAS collision avoidance,
>
> because TCAS must receive ungarbled Mode C altitude replies to function."
>
>
>
> It's not clear to me from that sentence that the gliders will be
>
> completely invisible to the TCAS _system_, only that it's collision
>
> avoidance functions won't work. Does the approaching, TCAS equipped
>
> aircraft get _any_ indication there are aircraft with transponders in
>
> that situation?
>
>
>
> I understand TCAS will work much better if there is Mode C transponders
>
> have some separation from each other. I'm just finding it hard to
>
> understand that a TCAS system will be completely unaware of a bunch of
>
> transponders, even if they are close together.
>
>
>
> Does ATC see anything out there, even if the TCAS system can not?

The danger here is this is not written for a technical audience and is confusing on multiple levels.

Firstly you can have several Mode-C equipped gliders in a gaggle or otherwise close by and the TCAS may well decode the transponders and see them as individual targets with valid direction, range and altitude data. As I mentioned with the decorrelators (or called "degarblers") and other tricks TCAS can handle some degree of garbling.

The mention of "TCAS collision avoidance" is likely meaning the RA (resolution advisory) capability of TCAS II, and if you have any threat that the Mode-C altitude replies really are not being clearly read then the RA part of TCAS II can not/will not function at all.

The TCAS may display a threat direction/range even of the altitude information is being garbled but there is no simple guarantee in garbled environment of what exactly will happen, it may or may not display all the aircraft with or without altitude data or (hopefully rarely) with incorrect altitude. But what matters really is the TA and RA and you really need the Mode C replies decoded properly for that. I expect TCAS I to be very useful against Mode C equipped gliders in usual buddy flying or small gaggles. Fly an airliner straight into a large (vertically spaced) gaggle of gliders and I have zero expectations that it will have a clue what to do with an RA, and that RA may well fly the airliner into a collision. OTOH I expect the gaggle to also be visible on the TCAS display -- not that I ever want to rely on the pilots looking a that display. An airliner going into a huge gaggle of Mode-S equipped gliders may also not fare well and TCAS may compute an unsafe RA (since RAs are based on altitude actions only and it can't/won't steer you around the gaggle). I'd hope ATC has noticed any very large gaggles and the gliders are in touch with ATC. So at some extent I find some of this worrying about what happens with large gaggles with Mode-C kind of unnecessary.

I hope ATC would be well aware there is say a large gaggle of gliders in a location (one benefit of a dedicated glider transponder code), be able to route traffic around that gaggle. And I'd hope that ATC would be savvy enough to suspect they may have very poor target acquisition, altitude reporting and garbling problems. And hopefully a large gaggle will show up even on primary radar in many locations. And I'd expect them to be upset if a large gargle is parked near where they usually want to route traffic. But hope is not always a good thing, go talk to your local ATC guys, radar techs are usually pretty friendly if you want to have a detailed talk with them.

You can always just ask your local ATC guys what they prefer if gliders are buddy flying etc. Most places I've asked (e.g. Reno approach in pre NORCAL days -- I dont' know about now) never felt they needed push for it but were happy to work with gliders buddy flying etc. where one or more of them wanted to go squawk standby.

Again the message is get a transponder if you fly near airliners and fast jets, lots of GA traffic etc. There is absolutely no need to replace a Mode C transponder, they work fine but if buying a new transponder it make no sense to get a Mode C when more modern Mode S transponders are available.

Darryl

Mike C

November 3rd 12, 04:48 AM

On Friday, November 2, 2012 10:17:18 PM UTC-6, Darryl Ramm wrote:
> On Friday, November 2, 2012 8:39:32 PM UTC-7, Eric Greenwell wrote:
>
> > On 11/2/2012 4:55 PM, Dave Nadler wrote:
>
> >
>
> > >
>
> >
>
> > > For heavens sake Eric, please read the link.
>
> >
>
> > > Pay attention to "fruiting" and "multiple transponders
>
> >
>
> > > all transmitting at almost the same time, creating
>
> >
>
> > > noise like everybody talking at the same time,
>
> >
>
> > > unreadable by ATC or TCAS".
>
> >
>
> > >
>
> >
>
> > > You know, kinda like RAS.
>
> >
>
> > >
>
> >
>
> > > For this reason:
>
> >
>
> > > - aircraft in formation only have ONE aircraft's
>
> >
>
> > > transponder turned on
>
> >
>
> > > - aircraft approaching Oshkosh are required to turn
>
> >
>
> > > their transponders OFF (except Mode S)
>
> >
>
> > > - the rest of the world has effectively outlawed
>
> >
>
> > > Mode A/C in favor of Mode S.
>
> >
>
> > >
>
> >
>
> > > Hope that's clear,
>
> >
>
> > > Best Regards, Dave
>
> >
>
> >
>
> >
>
> > Here's what the link says in #14: "A gaggle with multiple Mode C
>
> >
>
> > transponders active may be invisible to TCAS collision avoidance,
>
> >
>
> > because TCAS must receive ungarbled Mode C altitude replies to function.."
>
> >
>
> >
>
> >
>
> > It's not clear to me from that sentence that the gliders will be
>
> >
>
> > completely invisible to the TCAS _system_, only that it's collision
>
> >
>
> > avoidance functions won't work. Does the approaching, TCAS equipped
>
> >
>
> > aircraft get _any_ indication there are aircraft with transponders in
>
> >
>
> > that situation?
>
> >
>
> >
>
> >
>
> > I understand TCAS will work much better if there is Mode C transponders
>
> >
>
> > have some separation from each other. I'm just finding it hard to
>
> >
>
> > understand that a TCAS system will be completely unaware of a bunch of
>
> >
>
> > transponders, even if they are close together.
>
> >
>
> >
>
> >
>
> > Does ATC see anything out there, even if the TCAS system can not?
>
>
>
>
>
> The danger here is this is not written for a technical audience and is confusing on multiple levels.
>
>
>
> Firstly you can have several Mode-C equipped gliders in a gaggle or otherwise close by and the TCAS may well decode the transponders and see them as individual targets with valid direction, range and altitude data. As I mentioned with the decorrelators (or called "degarblers") and other tricks TCAS can handle some degree of garbling.
>
>
>
> The mention of "TCAS collision avoidance" is likely meaning the RA (resolution advisory) capability of TCAS II, and if you have any threat that the Mode-C altitude replies really are not being clearly read then the RA part of TCAS II can not/will not function at all.
>
>
>
> The TCAS may display a threat direction/range even of the altitude information is being garbled but there is no simple guarantee in garbled environment of what exactly will happen, it may or may not display all the aircraft with or without altitude data or (hopefully rarely) with incorrect altitude. But what matters really is the TA and RA and you really need the Mode C replies decoded properly for that. I expect TCAS I to be very useful against Mode C equipped gliders in usual buddy flying or small gaggles. Fly an airliner straight into a large (vertically spaced) gaggle of gliders and I have zero expectations that it will have a clue what to do with an RA, and that RA may well fly the airliner into a collision. OTOH I expect the gaggle to also be visible on the TCAS display -- not that I ever want to rely on the pilots looking a that display. An airliner going into a huge gaggle of Mode-S equipped gliders may also not fare well and TCAS may compute an unsafe RA (since RAs are based on altitude actions only and it can't/won't steer you around the gaggle). I'd hope ATC has noticed any very large gaggles and the gliders are in touch with ATC. So at some extent I find some of this worrying about what happens with large gaggles with Mode-C kind of unnecessary.
>
>
>
> I hope ATC would be well aware there is say a large gaggle of gliders in a location (one benefit of a dedicated glider transponder code), be able to route traffic around that gaggle. And I'd hope that ATC would be savvy enough to suspect they may have very poor target acquisition, altitude reporting and garbling problems. And hopefully a large gaggle will show up even on primary radar in many locations. And I'd expect them to be upset if a large gargle is parked near where they usually want to route traffic. But hope is not always a good thing, go talk to your local ATC guys, radar techs are usually pretty friendly if you want to have a detailed talk with them.
>
>
>
> You can always just ask your local ATC guys what they prefer if gliders are buddy flying etc. Most places I've asked (e.g. Reno approach in pre NORCAL days -- I dont' know about now) never felt they needed push for it but were happy to work with gliders buddy flying etc. where one or more of them wanted to go squawk standby.
Thanks Darryl. Appreciate the effort.

Mike

>
>
>
> Again the message is get a transponder if you fly near airliners and fast jets, lots of GA traffic etc. There is absolutely no need to replace a Mode C transponder, they work fine but if buying a new transponder it make no sense to get a Mode C when more modern Mode S transponders are available.
>
>
>
> Darryl

Dave Nadler

November 3rd 12, 02:59 PM

On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
> I am wondering if using Oshkosh as an example applicable to a few
> sailplanes, in a thermal, is not a bit of a strawman argument.

Oshkosh was used as an example of where Mode A/C cannot work.

> A separate point, it is my impression that traffic is so congested
> there that the controllers are overwhelmed, not that the signals are
> garbled and unreadable.

"Your impression" ? The controllers are not overwhelmed, they use
appropriate tools and manage the highest traffic density anywhere,
very professionally. As you would know if you've flown into
Oshkosh (or in the airshow ;-)

> Mode C is valid, safe and not the worthless tired technology
> that it seems to be portrayed as.

Sure, which is why Mode C was phased out in Germany years ago,
with the rest of the world following...

For new installations, get Mode S and we'll all be happier
with the results. And it won't have to be replaced if/when
FAA catches up with the rest of the world (not holding my
breath).

Mode C does work in many cases, but...

[email protected]

November 3rd 12, 03:23 PM

On Friday, November 2, 2012 11:17:18 PM UTC-5, Darryl Ramm wrote:
> On Friday, November 2, 2012 8:39:32 PM UTC-7, Eric Greenwell wrote:
>
> > On 11/2/2012 4:55 PM, Dave Nadler wrote:
>
> >
>
> > >
>
> >
>
> > > For heavens sake Eric, please read the link.
>
> >
>
> > > Pay attention to "fruiting" and "multiple transponders
>
> >
>
> > > all transmitting at almost the same time, creating
>
> >
>
> > > noise like everybody talking at the same time,
>
> >
>
> > > unreadable by ATC or TCAS".
>
> >
>
> > >
>
> >
>
> > > You know, kinda like RAS.
>
> >
>
> > >
>
> >
>
> > > For this reason:
>
> >
>
> > > - aircraft in formation only have ONE aircraft's
>
> >
>
> > > transponder turned on
>
> >
>
> > > - aircraft approaching Oshkosh are required to turn
>
> >
>
> > > their transponders OFF (except Mode S)
>
> >
>
> > > - the rest of the world has effectively outlawed
>
> >
>
> > > Mode A/C in favor of Mode S.
>
> >
>
> > >
>
> >
>
> > > Hope that's clear,
>
> >
>
> > > Best Regards, Dave
>
> >
>
> >
>
> >
>
> > Here's what the link says in #14: "A gaggle with multiple Mode C
>
> >
>
> > transponders active may be invisible to TCAS collision avoidance,
>
> >
>
> > because TCAS must receive ungarbled Mode C altitude replies to function.."
>
> >
>
> >
>
> >
>
> > It's not clear to me from that sentence that the gliders will be
>
> >
>
> > completely invisible to the TCAS _system_, only that it's collision
>
> >
>
> > avoidance functions won't work. Does the approaching, TCAS equipped
>
> >
>
> > aircraft get _any_ indication there are aircraft with transponders in
>
> >
>
> > that situation?
>
> >
>
> >
>
> >
>
> > I understand TCAS will work much better if there is Mode C transponders
>
> >
>
> > have some separation from each other. I'm just finding it hard to
>
> >
>
> > understand that a TCAS system will be completely unaware of a bunch of
>
> >
>
> > transponders, even if they are close together.
>
> >
>
> >
>
> >
>
> > Does ATC see anything out there, even if the TCAS system can not?
>
>
>
>
>
> The danger here is this is not written for a technical audience and is confusing on multiple levels.
>
>
>
> Firstly you can have several Mode-C equipped gliders in a gaggle or otherwise close by and the TCAS may well decode the transponders and see them as individual targets with valid direction, range and altitude data. As I mentioned with the decorrelators (or called "degarblers") and other tricks TCAS can handle some degree of garbling.
>
>
>
> The mention of "TCAS collision avoidance" is likely meaning the RA (resolution advisory) capability of TCAS II, and if you have any threat that the Mode-C altitude replies really are not being clearly read then the RA part of TCAS II can not/will not function at all.
>
>
>
> The TCAS may display a threat direction/range even of the altitude information is being garbled but there is no simple guarantee in garbled environment of what exactly will happen, it may or may not display all the aircraft with or without altitude data or (hopefully rarely) with incorrect altitude. But what matters really is the TA and RA and you really need the Mode C replies decoded properly for that. I expect TCAS I to be very useful against Mode C equipped gliders in usual buddy flying or small gaggles. Fly an airliner straight into a large (vertically spaced) gaggle of gliders and I have zero expectations that it will have a clue what to do with an RA, and that RA may well fly the airliner into a collision. OTOH I expect the gaggle to also be visible on the TCAS display -- not that I ever want to rely on the pilots looking a that display. An airliner going into a huge gaggle of Mode-S equipped gliders may also not fare well and TCAS may compute an unsafe RA (since RAs are based on altitude actions only and it can't/won't steer you around the gaggle). I'd hope ATC has noticed any very large gaggles and the gliders are in touch with ATC. So at some extent I find some of this worrying about what happens with large gaggles with Mode-C kind of unnecessary.
>
>
>
> I hope ATC would be well aware there is say a large gaggle of gliders in a location (one benefit of a dedicated glider transponder code), be able to route traffic around that gaggle. And I'd hope that ATC would be savvy enough to suspect they may have very poor target acquisition, altitude reporting and garbling problems. And hopefully a large gaggle will show up even on primary radar in many locations. And I'd expect them to be upset if a large gargle is parked near where they usually want to route traffic. But hope is not always a good thing, go talk to your local ATC guys, radar techs are usually pretty friendly if you want to have a detailed talk with them.
>
>
>
> You can always just ask your local ATC guys what they prefer if gliders are buddy flying etc. Most places I've asked (e.g. Reno approach in pre NORCAL days -- I dont' know about now) never felt they needed push for it but were happy to work with gliders buddy flying etc. where one or more of them wanted to go squawk standby.
>
>
>
> Again the message is get a transponder if you fly near airliners and fast jets, lots of GA traffic etc. There is absolutely no need to replace a Mode C transponder, they work fine but if buying a new transponder it make no sense to get a Mode C when more modern Mode S transponders are available.
>
>
>
> Darryl

Not directly related to the multiple C-mode transmits discussed here but still pertaining to Darryl's urging to get a transponder: After a season of 1202 (and last year's 1201) dedicated code here in the Chicago area, I have to praise the group that made this happen for us glider guiders. Our club lives under the approach path over Joliet VOR into Midway and the jets are often at around 5,000'. They reliably divert when we start flying in the area without us being in contact with Approach. Going North through the Aurora D airspace, I hear them on the tower frequency point out "glider at 5,200' SW of field" to approaching and departing traffic before I call them to say my intentions. Passing by a very busy sky jump operation to the West of us, they actually called me twice this year on 123.3 because they had gotten a phone or radio call from ATC pointing out a glider target close to their operations. Being identified as a glider without being necessarily in contact with ATC is very helpful. Get a transponder, please!

Herb

Mike C

November 3rd 12, 03:40 PM

On Saturday, November 3, 2012 8:59:11 AM UTC-6, Dave Nadler wrote:
> On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
>
> > I am wondering if using Oshkosh as an example applicable to a few
>
> > sailplanes, in a thermal, is not a bit of a strawman argument.
>
>
>
> Oshkosh was used as an example of where Mode A/C cannot work.
>
>
>
> > A separate point, it is my impression that traffic is so congested
>
> > there that the controllers are overwhelmed, not that the signals are
>
> > garbled and unreadable.
>
>
>
> "Your impression" ? The controllers are not overwhelmed, they use
>
> appropriate tools and manage the highest traffic density anywhere,
>
> very professionally. As you would know if you've flown into
>
> Oshkosh (or in the airshow ;-)
>
>
>
> > Mode C is valid, safe and not the worthless tired technology
>
> > that it seems to be portrayed as.
>
>
>
> Sure, which is why Mode C was phased out in Germany years ago,
>
> with the rest of the world following...
>
>
>
> For new installations, get Mode S and we'll all be happier
>
> with the results. And it won't have to be replaced if/when
>
> FAA catches up with the rest of the world (not holding my
>
> breath).
>
>
>
> Mode C does work in many cases, but...

Eric Greenwell[_4_]

November 3rd 12, 04:21 PM

On 11/2/2012 4:55 PM, Dave Nadler wrote:

>
> For this reason:
> - aircraft in formation only have ONE aircraft's
> transponder turned on
> - aircraft approaching Oshkosh are required to turn
> their transponders OFF (except Mode S)
> - the rest of the world has effectively outlawed
> Mode A/C in favor of Mode S.
>
> Hope that's clear,
> Best Regards, Dave

What to do is not at all clear to me. I've never been in a thermal that
decided to turn off some transponders, and I don't hear of any contests
where a protocol was put in place to achieve this. For example, how does
this statement "aircraft in formation only have ONE aircraft's
transponder turned on" apply in these situations; i.e., what constitutes
a "formation"?

- two gliders thermalling at the same altitude? Three? Four? Five?

- How about 10 gliders spread over two thousand feet of altitude? Should
only one have it's transponder on, or should the gliders at the top and
bottom have them on? Or one transponder every 1000'?

- Or two gliders cruising together: are they a formation if they are
100' apart? 500'? 1000'? Or if it's three gliders? Four?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Dave Nadler

November 3rd 12, 04:57 PM

On Saturday, November 3, 2012 12:22:00 PM UTC-4, Eric Greenwell wrote:
> What to do is not at all clear to me. I've never been in a thermal that
> decided to turn off some transponders, and I don't hear of any contests
> where a protocol was put in place to achieve this. For example, how does
> this statement "aircraft in formation only have ONE aircraft's
> transponder turned on" apply in these situations; i.e., what constitutes
> a "formation"?
>
> - two gliders thermalling at the same altitude? Three? Four? Five?
> - How about 10 gliders spread over two thousand feet of altitude? Should
> only one have it's transponder on, or should the gliders at the top and
> bottom have them on? Or one transponder every 1000'?
> - Or two gliders cruising together: are they a formation if they are
> 100' apart? 500'? 1000'? Or if it's three gliders? Four?
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
> email me)

Get a Mode S transponder so you don't have to worry about this !

Dan Marotta

November 3rd 12, 05:01 PM

Just had to change the atrocious spelling in the subject line...

"Dave Nadler" > wrote in message
...
> On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
>> I am wondering if using Oshkosh as an example applicable to a few
>> sailplanes, in a thermal, is not a bit of a strawman argument.
>
> Oshkosh was used as an example of where Mode A/C cannot work.
>
>> A separate point, it is my impression that traffic is so congested
>> there that the controllers are overwhelmed, not that the signals are
>> garbled and unreadable.
>
> "Your impression" ? The controllers are not overwhelmed, they use
> appropriate tools and manage the highest traffic density anywhere,
> very professionally. As you would know if you've flown into
> Oshkosh (or in the airshow ;-)
>
>> Mode C is valid, safe and not the worthless tired technology
>> that it seems to be portrayed as.
>
> Sure, which is why Mode C was phased out in Germany years ago,
> with the rest of the world following...
>
> For new installations, get Mode S and we'll all be happier
> with the results. And it won't have to be replaced if/when
> FAA catches up with the rest of the world (not holding my
> breath).
>
> Mode C does work in many cases, but...

Darryl Ramm

November 3rd 12, 05:40 PM

Dave Nadler > wrote:
> On Saturday, November 3, 2012 12:22:00 PM UTC-4, Eric Greenwell wrote:
>> What to do is not at all clear to me. I've never been in a thermal that
>> decided to turn off some transponders, and I don't hear of any contests
>> where a protocol was put in place to achieve this. For example, how does
>> this statement "aircraft in formation only have ONE aircraft's
>> transponder turned on" apply in these situations; i.e., what constitutes
>> a "formation"?
>>
>> - two gliders thermalling at the same altitude? Three? Four? Five?
>> - How about 10 gliders spread over two thousand feet of altitude? Should
>> only one have it's transponder on, or should the gliders at the top and
>> bottom have them on? Or one transponder every 1000'?
>> - Or two gliders cruising together: are they a formation if they are
>> 100' apart? 500'? 1000'? Or if it's three gliders? Four?
>>
>> --
>> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>> email me)
>
> Get a Mode S transponder so you don't have to worry about this !

No! Just keep using your Mode C and don't worry about it. This whole
excessive worry about a what-if corner case is typical post-season
rasterbation, can we please at least get back to PW5 bashing?

Darryl

Darryl Ramm

November 3rd 12, 05:40 PM

"Dan Marotta" > wrote:
> Just had to change the atrocious spelling in the subject line...
>
And that mostly just annoys a lot of people, forks the thread in many
newsreaders etc. Leave usenet subject lines alone please.

Darryl

Eric Greenwell[_4_]

November 3rd 12, 07:19 PM

I'm pleased to know a gaggle full of Mode C transponders doesn't become
invisible to ATC and probably not even TCAS, but is just more difficult
for the system.

If it really became invisible, then it would important/critical for a
gaggle to coordinate their transponder usage, a big hassle if it's more
than a few gliders. It would lead to a lot of radio discussion to decide
who shuts off their transponder, and who turns it back on when the
"designated transponder" leaves the gaggle, and likely leading to some
pilots forgetting to turn their transponder back on when they leave.

On 11/2/2012 9:17 PM, Darryl Ramm wrote:

>> Does ATC see anything out there, even if the TCAS system can not?
>
>
> The danger here is this is not written for a technical audience and
> is confusing on multiple levels.
>
> Firstly you can have several Mode-C equipped gliders in a gaggle or
> otherwise close by and the TCAS may well decode the transponders and
> see them as individual targets with valid direction, range and
> altitude data. As I mentioned with the decorrelators (or called
> "degarblers") and other tricks TCAS can handle some degree of
> garbling.
>
> The mention of "TCAS collision avoidance" is likely meaning the RA
> (resolution advisory) capability of TCAS II, and if you have any
> threat that the Mode-C altitude replies really are not being clearly
> read then the RA part of TCAS II can not/will not function at all.
>
> The TCAS may display a threat direction/range even of the altitude
> information is being garbled but there is no simple guarantee in
> garbled environment of what exactly will happen, it may or may not
> display all the aircraft with or without altitude data or (hopefully
> rarely) with incorrect altitude. But what matters really is the TA
> and RA and you really need the Mode C replies decoded properly for
> that. I expect TCAS I to be very useful against Mode C equipped
> gliders in usual buddy flying or small gaggles. Fly an airliner
> straight into a large (vertically spaced) gaggle of gliders and I
> have zero expectations that it will have a clue what to do with an
> RA, and that RA may well fly the airliner into a collision. OTOH I
> expect the gaggle to also be visible on the TCAS display -- not that
> I ever want to rely on the pilots looking a that display. An airliner
> going into a huge gaggle of Mode-S equipped gliders may also not fare
> well and TCAS may compute an unsafe RA (since RAs are based on
> altitude actions only and it can't/won't steer you around the
> gaggle). I'd hope ATC has noticed any very large gaggles and the
> gliders are in touch with ATC. So at some extent I find some of this
> worrying about what happens with large gaggles with Mode-C kind of
> unnecessary.
>
> I hope ATC would be well aware there is say a large gaggle of gliders
> in a location (one benefit of a dedicated glider transponder code),
> be able to route traffic around that gaggle. And I'd hope that ATC
> would be savvy enough to suspect they may have very poor target
> acquisition, altitude reporting and garbling problems. And hopefully
> a large gaggle will show up even on primary radar in many locations.
> And I'd expect them to be upset if a large gargle is parked near
> where they usually want to route traffic. But hope is not always a
> good thing, go talk to your local ATC guys, radar techs are usually
> pretty friendly if you want to have a detailed talk with them.
>
> You can always just ask your local ATC guys what they prefer if
> gliders are buddy flying etc. Most places I've asked (e.g. Reno
> approach in pre NORCAL days -- I dont' know about now) never felt
> they needed push for it but were happy to work with gliders buddy
> flying etc. where one or more of them wanted to go squawk standby.
>
> Again the message is get a transponder if you fly near airliners and
> fast jets, lots of GA traffic etc. There is absolutely no need to
> replace a Mode C transponder, they work fine but if buying a new
> transponder it make no sense to get a Mode C when more modern Mode S
> transponders are available.
>
> Darryl
>

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Dave Nadler

November 3rd 12, 07:42 PM

On Saturday, November 3, 2012 3:19:53 PM UTC-4, Eric Greenwell wrote:
> I'm pleased to know a gaggle full of Mode C transponders doesn't become
> invisible to ATC and probably not even TCAS

Absolutely wrong.

It *may* work.
It is a probability problem, related to
number of aircraft, antenna installation,
aircraft position, orientation, and bank, etc.

Eric Greenwell[_4_]

November 3rd 12, 09:20 PM

On 11/3/2012 9:57 AM, Dave Nadler wrote:
> On Saturday, November 3, 2012 12:22:00 PM UTC-4, Eric Greenwell wrote:
>> What to do is not at all clear to me. I've never been in a thermal that
>> decided to turn off some transponders, and I don't hear of any contests
>> where a protocol was put in place to achieve this. For example, how does
>> this statement "aircraft in formation only have ONE aircraft's
>> transponder turned on" apply in these situations; i.e., what constitutes
>> a "formation"?
>>
>> - two gliders thermalling at the same altitude? Three? Four? Five?
>> - How about 10 gliders spread over two thousand feet of altitude? Should
>> only one have it's transponder on, or should the gliders at the top and
>> bottom have them on? Or one transponder every 1000'?
>> - Or two gliders cruising together: are they a formation if they are
>> 100' apart? 500'? 1000'? Or if it's three gliders? Four?
>>
>> --
>> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>> email me)
>
> Get a Mode S transponder so you don't have to worry about this !

Maybe I'm asking for details that nobody knows, and it appears that the
question hasn't even come up in contests where multiple Mode C gaggles
are likely routine.

Since at least 98% of my flying is not near other gliders, I'm not
motivated to upgrade to Mode S, and frankly, I don't expect significant
numbers of Mode C users to upgrade to Mode S, either, so I'm trying to
learn what is sensible to do during the 2% of the time I am near other
gliders.

Back to this: "Get a Mode S transponder so you don't have to worry about
this !"

So, a TCAS equipped aircraft will react properly to a Mode S transponder
in a big gaggle of Mode C equipped gliders - is that what you are
implying? I don't want to guess at this; I want to know what is actually
required for TCAS aircraft to be able to avoid a gaggle I'm in.

If so, the "formation protocol" in a gaggle could be to first find out
if at least one of the gliders is Mode S equipped, then all the Mode C
equipped gliders can leave their transponders on. Of course, that might
not protect the Mode C gliders circling 2000 feet above or below the
Mode S glider.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

Mike C

November 3rd 12, 09:25 PM

On Nov 3, 8:59*am, Dave Nadler > wrote:
> On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
> > I am wondering if using Oshkosh as an example applicable to a few
> > sailplanes, in a thermal, is not a bit of a strawman argument.
>
> Oshkosh was used as an example of where Mode A/C cannot work.
>
> > A separate point, it is my impression that *traffic is so congested
> > there that the controllers are overwhelmed, not that the signals are
> > garbled and unreadable.
>
> "Your impression" ? The controllers are not overwhelmed, they use
> appropriate tools and manage the highest traffic density anywhere,
> very professionally. As you would know if you've flown into
> Oshkosh (or in the airshow ;-)
>
> > Mode C is valid, safe and not the worthless tired technology
> > that it seems to be portrayed as.
>
> Sure, which is why Mode C was phased out in Germany years ago,
> with the rest of the world following...
>
> For new installations, get Mode S and we'll all be happier
> with the results. And it won't have to be replaced if/when
> FAA catches up with the rest of the world (not holding my
> breath).
>
> Mode C does work in many cases, but...

Mike C

November 3rd 12, 09:29 PM

Darryl Ramm

November 3rd 12, 09:56 PM

On Saturday, November 3, 2012 2:29:03 PM UTC-7, Mike C wrote:
> On Nov 3, 8:59*am, Dave Nadler > wrote:
>
> > On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
>
> > > I am wondering if using Oshkosh as an example applicable to a few
>
> > > sailplanes, in a thermal, is not a bit of a strawman argument.
>
> >
>
> > Oshkosh was used as an example of where Mode A/C cannot work.
>
> >
>
> > > A separate point, it is my impression that *traffic is so congested
>
> > > there that the controllers are overwhelmed, not that the signals are
>
> > > garbled and unreadable.
>
> >
>
> > "Your impression" ? The controllers are not overwhelmed, they use
>
> > appropriate tools and manage the highest traffic density anywhere,
>
> > very professionally. As you would know if you've flown into
>
> > Oshkosh (or in the airshow ;-)
>
> >
>
> > > Mode C is valid, safe and not the worthless tired technology
>
> > > that it seems to be portrayed as.
>
> >
>
> > Sure, which is why Mode C was phased out in Germany years ago,
>
> > with the rest of the world following...
>
> >
>
> > For new installations, get Mode S and we'll all be happier
>
> > with the results. And it won't have to be replaced if/when
>
> > FAA catches up with the rest of the world (not holding my
>
> > breath).
>
> >
>
> > Mode C does work in many cases, but...
>
>
>
> Dave,
>
>
>
> Are you sure that the reason that formation pilots only have one
>
> transponder on, is not because of collision alerts with aircraft in
>
> close proximity of each other? That is what I was told. Also told the
>
> reason transponders are turned off is because of alerts in heavy
>
> traffic
>
>
>
> Mike.

No, the reason for all but the formation leader in going squawk standby in formations is 'garbling' with all the Mode A/C transponders otherwise replying to the same interrogation and the SSR *possibly* being unable to decode the signal from each aircraft. Modern SSR systems also have pretty advanced decorrelators that can untangle several overlapping replies. This is something that dates back to the earliest days of SSR radar and is discussed in the FAA AIM, ATC Procedures section.

PCAS type systems may also be affected by garbling, but this is not the reason ATC cares about it. You can sometimes see what I expect are the garbling effects with Mode A/C transponders with when you formation fly with an aircraft and it dissapears intermittently.

But to Eric's points, just don't worry about all this wonky geek crap. If any of this was really worth worrying about you'd have the ATC folks who work closely with the glider community in busy traffic places raising it as an issue. And AFAIK they have never done that--all the discussions I have with those folks, both civil and military is they just want to see transponder adoption near their airspace, Mode C, Mode S they don't care.

And fly the glider. I'd hate to be in gaggles where folks are coordinating who's turning off transponders, then you have to remember to turn them back on again.

OTOH if you are flying in large gaggles near a busy ATC facility you have lots of very real reasons to be talking to your friendly ATC folks, not there are far more important things to talk about than the possibility of garbling. And I certainly expect those ATC folks to notice the presence of large gaggles even with severe garbling.

Darryl

Dan Marotta

November 4th 12, 12:33 AM

Sorry - I was unaware of that.

Guess I'll have to just suffer the bad spelin' and gramr...

"Darryl Ramm" > wrote in message
...
> "Dan Marotta" > wrote:
>> Just had to change the atrocious spelling in the subject line...
>>
> And that mostly just annoys a lot of people, forks the thread in many
> newsreaders etc. Leave usenet subject lines alone please.
>
> Darryl

Dan Marotta

November 4th 12, 12:35 AM

Back in my military flying days, only the flight leader squawked; wingmen
set their transponders to STBY. When/if the formation broke up, everyone
squawked an assigned code.

"Mike C" > wrote in message
...
On Nov 3, 8:59 am, Dave Nadler > wrote:
> On Friday, November 2, 2012 8:45:43 PM UTC-4, Mike C wrote:
> > I am wondering if using Oshkosh as an example applicable to a few
> > sailplanes, in a thermal, is not a bit of a strawman argument.
>
> Oshkosh was used as an example of where Mode A/C cannot work.
>
> > A separate point, it is my impression that traffic is so congested
> > there that the controllers are overwhelmed, not that the signals are
> > garbled and unreadable.
>
> "Your impression" ? The controllers are not overwhelmed, they use
> appropriate tools and manage the highest traffic density anywhere,
> very professionally. As you would know if you've flown into
> Oshkosh (or in the airshow ;-)
>
> > Mode C is valid, safe and not the worthless tired technology
> > that it seems to be portrayed as.
>
> Sure, which is why Mode C was phased out in Germany years ago,
> with the rest of the world following...
>
> For new installations, get Mode S and we'll all be happier
> with the results. And it won't have to be replaced if/when
> FAA catches up with the rest of the world (not holding my
> breath).
>
> Mode C does work in many cases, but...

Dave,

Are you sure that the reason that formation pilots only have one
transponder on, is not because of collision alerts with aircraft in
close proximity of each other? That is what I was told. Also told the
reason transponders are turned off is because of alerts in heavy
traffic

Mike.

November 4th 12, 01:18 AM

On Saturday, November 3, 2012 6:33:26 PM UTC-6, Dan Marotta wrote:
> Sorry - I was unaware of that.

> Guess I'll have to just suffer the bad spelin' and gramr...

> >> Just had to change the atrocious spelling in the subject line...
>

Dan,
God, I am so sorry for making you suffer. Can I buy you dinner at the next convention? I swear that if I start another TX thread I will not use a plural tense and end it in a Z. You have my word.
The reason I started this thread is because there seems to be an ever increasing variety of these things (Including something called a Sandia STX165 on WW) and I was wondering if I would end up with something that would be obsolete with the implementation of ADS-B. I have intended Mode S from the start.
I flew most of last season with the portable PF and it worked great with transponders and the occasional ADS-B but I did not get much chance to fly with other PFs.
Will probably go with the Trig. Thanks to everyone for the comments.

Darryl Ramm

November 4th 12, 02:03 AM

On Saturday, November 3, 2012 6:18:45 PM UTC-7, K wrote:
> On Saturday, November 3, 2012 6:33:26 PM UTC-6, Dan Marotta wrote:
>
> > Sorry - I was unaware of that.
>
>
>
> > Guess I'll have to just suffer the bad spelin' and gramr...
>
>
>
> > >> Just had to change the atrocious spelling in the subject line...
>
> >
>
>
>
> Dan,
>
> God, I am so sorry for making you suffer. Can I buy you dinner at the next convention? I swear that if I start another TX thread I will not use a plural tense and end it in a Z. You have my word.
>
> The reason I started this thread is because there seems to be an ever increasing variety of these things (Including something called a Sandia STX165 on WW) and I was wondering if I would end up with something that would be obsolete with the implementation of ADS-B. I have intended Mode S from the start.
>
> I flew most of last season with the portable PF and it worked great with transponders and the occasional ADS-B but I did not get much chance to fly with other PFs.
>
> Will probably go with the Trig. Thanks to everyone for the comments.

So there is one possible thing to consider with Mode-S transponders and possible ADS-B data-out futures. If I was buying any Mode-S transponder today lookign for that future ADS-B data-out possibility I would buy a higher power output transponder (in the case of the Trig that's the TT-22).

This is different than the operation as a transponder and any of the class 1 / class 2 approval and suitable use questions that have come up on r.a.s in the past. Its just that AFAIK the FAA is still not clear on final ADS-B data-out power requirements. The Trig TT-21 and similar lower power transponders all meet RTCA DO-260B and other standards for 1090ES data-out but its unclear (at least to me) if that will be acceptable to the FAA or if they will actually end up requiring a higher output power to enable communications via the FAA's ADS-B GBTs (Ground Based Transceivers). While I would have hoped the FAA spaced the GBTs close enough that current spec low-power 1090ES data-out would be compatible its not clear that is what finally happened. And who knows what would happen in practice, possibly the devices could still be installed, but if an install needs an STC (as currently) or TSO approved device or is otherwise strictly enforced you may have no ADS-B data-out option.

Sorry for the lack of hard info, I don't want to worry anybody and I wish I was more up to speed on the status here. This is just a personal caution, and again remember that if you are buying a transponder for ADS-B data-out futures that is all currently a world of hurt, at least for certified aircraft, with STC requirements and IFR/TSO'ed GPS requirements. And there are uncertainties with what will happen with 'non-complaint' installs in experiential aircraft. Personally I'd get a Trig TT-21 or TT-22 today for lots of reasons, but probably go for the TT-22 just to cover my ass a bit on the output power uncertainty.

I'd not hold my breath for the FAA to sort out ADS-B data-out mess. Both the Trig TT-21 and TT-22 are just fantastic transponders. Another way to look at either of these is in a decade you just throw them out, that two hundred dollars or so per year. Money likely very well spent if fly near airliners, fast jets and busy GA traffic.

As stated before but several of us here, buying a Mode C transponder today makes _no_ sense, and the Sandia STX165 is a Mode C transponder. It seems a case of a vendor following silly FAA thinking that the future for GA is Mode C + UAT data out/in. Unfortunately organizations like AOPA also wanted/supported this, at least in concept, instead of calling bull**** on the whole FAA ADS-B dual-link mess.

Thanks for flying with a transponder.

Darryl

mike

November 4th 12, 03:28 AM

On Nov 3, 8:03*pm, Darryl Ramm > wrote:
> On Saturday, November 3, 2012 6:18:45 PM UTC-7, K wrote:
> > On Saturday, November 3, 2012 6:33:26 PM UTC-6, Dan Marotta wrote:
>
> > > Sorry - I was unaware of that.
>
> > > Guess I'll have to just suffer the bad spelin' and gramr...
>
> > > >> Just had to change the atrocious spelling in the subject line...
>
> > Dan,
>
> > God, I am so sorry for making you suffer. Can I buy you dinner at the next convention? I swear that if I start another TX thread I will not use a plural tense and end it in a Z. You have my word.
>
> > The reason I started this thread is because there seems to be an ever increasing variety of these things (Including something called a Sandia STX165 on WW) and I was wondering if I would end up with something that would be obsolete with the implementation of ADS-B. I have intended Mode S from the start.
>
> > I flew most of last season with the portable PF and it worked great with transponders and the occasional ADS-B but I did not get much chance to fly with other PFs.
>
> > Will probably go with the Trig. Thanks to everyone for the comments.
>
> So there is one possible thing to consider with Mode-S transponders and possible ADS-B data-out futures. If I was buying any Mode-S transponder today lookign for that future ADS-B data-out possibility I would buy a higher power output transponder (in the case of the Trig that's the TT-22).
>
> This is different than the operation as a transponder and any of the class 1 / class 2 approval and suitable use questions that have come up on r.a.s in the past. Its just that AFAIK the FAA is still not clear on final ADS-B data-out power requirements. The Trig TT-21 and similar lower power transponders all meet RTCA DO-260B and other standards for 1090ES data-out but its unclear (at least to me) if that will be acceptable to the FAA or if they will actually end up requiring a higher output power to enable communications via the FAA's ADS-B GBTs (Ground Based Transceivers). While I would have hoped the FAA spaced the GBTs close enough that current spec low-power 1090ES data-out would be compatible its not clear that is what finally happened. And who knows what would happen in practice, possibly the devices could still be installed, but if an install needs an STC (as currently) or TSO approved device or is otherwise strictly enforced you may have no ADS-B data-out option.
>
> Sorry for the lack of hard info, I don't want to worry anybody and I wish I was more up to speed on the status here. This is just a personal caution, and again remember that if you are buying a transponder for ADS-B data-out futures that is all currently a world of hurt, at least for certified aircraft, *with STC requirements and IFR/TSO'ed GPS requirements. And there are uncertainties with what will happen with 'non-complaint' installs in experiential aircraft. Personally I'd get a Trig TT-21 or TT-22 today for lots of reasons, but probably go for the TT-22 just to cover my ass a bit on the output power uncertainty.
>
> I'd not hold my breath for the FAA to sort out ADS-B data-out mess. Both the Trig TT-21 and TT-22 are just fantastic transponders. Another way to look at either of these is in a decade you just throw them out, that two hundred dollars or so per year. Money likely very well spent if fly near airliners, fast jets and busy GA traffic.
>
> As stated before but several of us here, buying a Mode C transponder today makes _no_ sense, and the Sandia STX165 is a Mode C transponder. It seems a case of a vendor following silly FAA thinking that the future for GA is Mode C + UAT data out/in. Unfortunately organizations like AOPA also wanted/supported this, at least in concept, instead of calling bull**** on the whole FAA ADS-B dual-link mess.
>
> Thanks for flying with a transponder.
>
> Darryl

Thanks for the info Darryl.

My choice at the time was a Mode S and no Flarm or a really great deal
on a Sandia Mode C and a Flarm.

Some of us have to make compromises based on income.

Mike

Dan Marotta

November 4th 12, 03:24 PM

K,

Where/when's the convention? I haven't been to one yet. And please don't
take my rants personal; it's just that time of year...

I've got a Trig TT22 and am very happy with it. I don't see jets nearly as
closely as I used to. I had some installation problems, mainly with routing
the wiring from under the floor of my cockpit to the instrument panel and a
shorted wire in the DB-9 connector. The factory support was quick and
responsive and I made repairs. I bought a prewired cable but had to cut one
connector off to route the cable. The short circuit was my fault. Since
then, it has performed flawlessly.

"K" > wrote in message
...
On Saturday, November 3, 2012 6:33:26 PM UTC-6, Dan Marotta wrote:
> Sorry - I was unaware of that.

> Guess I'll have to just suffer the bad spelin' and gramr...

> >> Just had to change the atrocious spelling in the subject line...
>

Dan,
God, I am so sorry for making you suffer. Can I buy you dinner at the next
convention? I swear that if I start another TX thread I will not use a
plural tense and end it in a Z. You have my word.
The reason I started this thread is because there seems to be an ever
increasing variety of these things (Including something called a Sandia
STX165 on WW) and I was wondering if I would end up with something that
would be obsolete with the implementation of ADS-B. I have intended Mode S
from the start.
I flew most of last season with the portable PF and it worked great with
transponders and the occasional ADS-B but I did not get much chance to fly
with other PFs.
Will probably go with the Trig. Thanks to everyone for the comments.