Transponder article updated with Trig info

[Eric Greenwell]

This article, originally in Soaring (Feb 2002) was updated recently to
include information on the Trig TT21 transponder. You can download it from

http://tinyurl.com/yg76qo9

It will also be available on the Soaring Safety Foundation website later
this month:

http://soaringsafety.org/

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl.com/yg76qo9

- "A Guide to Self-launching Sailplane Operation" Much of what you need to know tinyurl.com/yfs7tnz

[jim archer]

On Feb 10, 1:47*pm, Eric Greenwell > wrote:
> This article, originally in Soaring (Feb 2002) was updated recently to
> include information on the Trig TT21 transponder. You can download it from
>
> http://tinyurl.com/yg76qo9
>
> It will also be available on the Soaring Safety Foundation website later
> this month:
>
> http://soaringsafety.org/
>
> --
> Eric Greenwell - Washington State, USA (netto to net to email me)
>
> - "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl..com/yg76qo9
>
> - "A Guide to Self-launching Sailplane Operation" Much of what you need to know tinyurl.com/yfs7tnz

Funny, I just downloaded the previous version this morning looking for
information on the trig. Thanks again Mr. Greenwell

[weersch[_2_]]

Hi Eric
Very good overview article. Thanks for that.
I think you are maybe a bit too optimistic about the PCAS systems.
Please don't get me wrong.
I would still recommend everybody to get one.
But everyone needs to understand the limitations.
I don't have any pertinent data, but this is what I sense:
PCAS is not "watertight".
I hear continuous stories about missed threats.
Last weekend my (transponder-on) threat did not show up on my friend's
PCAS.
You already indicate that it works "well", not perfect.
To stay with your phrasing and adjusting it a bit.
If you fly in Reno area and have 10 surpises a year, the PCAS will
probably indicate 8 out if those 10.
But not eliminate all 10 out of 10 surpises.
My understanding is also that if a Mode C transponder does not get
interrogated (e.g. out of radar range), no threat will show up on your
PCAS.
For these remaining cases and all the other stuff without transponder,
you still very much need to keep your eyes out there.

All these tools are great to significantly reduce risks, but they do
not eliminate all risk.
The worst scenario is to replace the reduced risk with complacency,
assuming that everything is safe now with your fully tooled up glider.
According to Murphy's law, the remaining risk will come and bite you.

Hans Van Weersch
With "always-on, radio-checked" radio, "always-on, tested"
transponder, "always-on" instruments, 25Ah of battery (going to 31.5
Ah) and getting an MRX-A soon.

[Eric Greenwell]

weersch wrote:
> Hi Eric
> Very good overview article. Thanks for that.
> I think you are maybe a bit too optimistic about the PCAS systems.
> Please don't get me wrong.
> I would still recommend everybody to get one.
> But everyone needs to understand the limitations.
> I don't have any pertinent data, but this is what I sense:
> PCAS is not "watertight".
>
True. The threat aircraft has to have an operating transponder with a
working antenna, and it's transponder must be interrogated by ground
radar or an aircraft with a TCAS system.
> I hear continuous stories about missed threats.
> Last weekend my (transponder-on) threat did not show up on my friend's
> PCAS.
> You already indicate that it works "well", not perfect.
> To stay with your phrasing and adjusting it a bit.
> If you fly in Reno area and have 10 surpises a year, the PCAS will
> probably indicate 8 out if those 10.
> But not eliminate all 10 out of 10 surpises.
>
8 out 10 is definitely working "well" by my standards! I would still buy
one if it was only 50% surprise elimination.
> My understanding is also that if a Mode C transponder does not get
> interrogated (e.g. out of radar range), no threat will show up on your
> PCAS.
>
It must be interrogated, but it doesn't require ground radar to be the
interrogator. It can be any aircraft (usually airliners, business jets,
some military) with a TCAS, too. If you are in an area with no ground
radar and no TCAS equipped aircraft, you probably don't have much
traffic to worry about, anyway.
> For these remaining cases and all the other stuff without transponder,
> you still very much need to keep your eyes out there.
>
Absolutely!

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl.com/yg76qo9

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

[Darryl Ramm]

Yo Hans

I do not think Eric is overselling PCAS.

Like all traffic awareness technology PCAS had limitations and people
really should try to understand those, but before mentioning some of
those let's clarify one thing... Yes PCAS only works if the threat
aircraft transponder is being interrogated. Both the interrogation to
the transponder from somewhere and transmission from the transponder
are ~1GHz so are absolutely line of sight. Interrogators include SSR
ground based radar, including civil and military terminal radar
(~60nm) as well as area radar (~250nm). Obviously this is line of
site, degrades as you get low and since the radar signal only fans up
in a wedge shape you also may also not get proper interrogation
overhead of the main radar beam. However in many situations your
transponder is being interrogated by several radars, but even more
usefully in many situation your transponder is also being interrogated
by multiple airborne interrogators such as TCAS and TCAD systems (like
the Garmin 800 series or L3 Skywatch). And effectively all airliners,
many corporate jets, many military transport, etc. have TCAS.

It is often suprising how you can be in some remote valley and yet see
the transponder being interrogated. That is airborne interrogators at
work.

Also lets clear up one misconception that blinky light or LCD thing on
most transponders that shows the transponder is being interrogated is
really not showing you what is going on. Yes if it is blinking your
transponder is being interrogated. But it is just saying it's talking,
it does not show you the actual interrogation rate (which could be
hundreds of times per second in busy airspace). So don't rely on the
blink rate to tell you you are in an area of high interrogation or
not. Obviously no blinking says no interrogations at all, which is not
good.

So for a sampling of some PCAS limitations....

PCAS relies on the user reading the manual, there are settings for
alert ranges, altitudes etc. on most units that the user should be
aware of. Also basic alerts, beeps etc. may be confusing unless the
person has read the manual and spent time playing with the unit.

PCAS relies on the other guy having a Mode C or Mode S transponder.

PCAS relies on the other guy turning on his transponder (I'll spot
friends who forgot to turn on the trasponder and let them know over
the radio).

PCAS relies on the other guy having his transponder correctly set to
Mode C (or "ALT") not accidentally put on Mode A.

PCAS relies on the threat aircraft transponder being interrogated. If
its not you get no warning. While it is amazing how many places do see
interrogations from radar, TCAS, TCAD etc. there are clearly places,
especially down low on ridges or in valleys etc. where relying on this
would not be a good idea.

PCAS relies on line of sight (or partially reflected off the airframe
etc.) signal from the transponder antenna to the PCAS antenna. So for
example if you are flying higher than the threat aircraft and you PCAS
antenna is partially blocked from below by the instruments and maybe
carbon fuselage and the threat glider has a transponder antenna
underneath... you get the picture... PCAS may not see the threat
glider or may assume it is far distant (becasue of the simple radio
radio power based guess that PCAS uses to approximate distance).
However you will often at least get some warning, amazingly the RF
signals do have ways of reflecting off aircraft surfaces etc. But
there are clearly cases where you don't see somebody you should and
this may explain many of those. More sophisticated PCAS installs might
have external or dual antennas (top and bottom), and more
sophisticated transponder installs might have two antennas as well but
that's a bit too much for most gliders.

PCAS relies on a vertically polarized signal. So things tend to work
best with transponder antennas pointing as much as possible up and
down and PCAS antennas doing the same. Both with a good view of the
sky.

PCAS uses relative altitude as the primary threat determinant and that
has issues. PCAS relies on the altitude difference a lot because the
range to the threat aircraft is guesstimated from the received power
and so the range is pretty inaccurate (but very useful to show a
closing threat). By contrast TCAS and TCAD use interrogation-response
times to much more accurately determine distance to the threat
aircraft. The relative altitude between you and the threat is
determined from the altitude encoded in the threat's transponder
signal and either the PCAS unit's internal altimeter or the altitude
it reads from your own transponder signal. One problem with this is
that the PCAS unit cannot generally tell what is a Mode C altitude
transmission and what is a Mode A transmission (ie. it's squawk code)
from the same transponder. (I can hear the next question... a Mode C
transponder has to both answer Mode C (altitude) and Mode A (squawk
code) interrogations). But the PCAS just sees a stream of bits and
does not know whether the transponder was asked by the interrogator to
send Altitude or Ident. The PCAS can do some smart guessing and things
like the Zaon MRX seem to do this very well, *but* if it get this
wrong it can think the threat aircraft is at some completely bogus
altitude far off from where it is. Since relative altitude is the
primary threat determinant the PCAS system might just ignore that
target. In practice this problem seem very very rare. BTW Mode S
transponders being interrogated Mode S don't have this "alaising"
problem.

Since PCAS systems uses altitude as the primary threat determinant a
relative altitude error of several hundred feet or so may make the
difference between a PCAS unit alarming on a threat or not. Check the
transponder altitudes in both your own and the threat aircraft are
reporting correctly and also if it has one check the internal
altimeter within the PCAS unit. You can usually get to this via a
menu. With a Zaon MRX for example it will try to read your local
transponders encoder altitude and base its relative altitude
measurements between the aircraft on that. If however it's internal
altimeter (measuring cockpit ambient pressure) seems off from that I
believe it can revert to using the internal altimeter. If you are
seeing strange or unreliable behavior that might be altitude reading
related I would check with Zaon.

---

So no technology is infalible. PCAS can be a temendous tool, but it
helps to understand how it works. I have flown with my MRX for about 5
years and think it was a great safety investment.

One of the major benefits I see with PCAS is once people fly with one
a little a response like "holy !@#$ I had no idea there was so much
stuff out there" is not uncommon. PCAS units acts both as as a useful
alert device and an effective reminder to keep a healthy visual scan
going, make radio calls, etc.

Did that help? (and Hans try to stay awake in my next transponder
presentation :-))


Darryl


On Feb 11, 3:08 pm, weersch > wrote:
> Hi Eric
> Very good overview article. Thanks for that.
> I think you are maybe a bit too optimistic about the PCAS systems.
> Please don't get me wrong.
> I would still recommend everybody to get one.
> But everyone needs to understand the limitations.
> I don't have any pertinent data, but this is what I sense:
> PCAS is not "watertight".
> I hear continuous stories about missed threats.
> Last weekend my (transponder-on) threat did not show up on my friend's
> PCAS.
> You already indicate that it works "well", not perfect.
> To stay with your phrasing and adjusting it a bit.
> If you fly in Reno area and have 10 surpises a year, the PCAS will
> probably indicate 8 out if those 10.
> But not eliminate all 10 out of 10 surpises.
> My understanding is also that if a Mode C transponder does not get
> interrogated (e.g. out of radar range), no threat will show up on your
> PCAS.
> For these remaining cases and all the other stuff without transponder,
> you still very much need to keep your eyes out there.
>
> All these tools are great to significantly reduce risks, but they do
> not eliminate all risk.
> The worst scenario is to replace the reduced risk with complacency,
> assuming that everything is safe now with your fully tooled up glider.
> According to Murphy's law, the remaining risk will come and bite you.
>
> Hans Van Weersch
> With "always-on, radio-checked" radio, "always-on, tested"
> transponder, "always-on" instruments, 25Ah of battery (going to 31.5
> Ah) and getting an MRX-A soon.

[Hagbard Celine]

When it came to the battery part of the article there was still
nothing on an specific NiMH or LiLon batteries. I was wondering if
anyone has tried either of the batteries from this company:
http://www.atsipowermanagement.co.uk/lynx.html 10 A/H in a PS1270 size
would be nice if it works.

[[email protected]]

On Feb 11, 11:36*pm, Darryl Ramm > wrote:
> Yo Hans
>
> I do not think Eric is overselling PCAS.
>


> Did that help? (and Hans try to stay awake in my next transponder
> presentation :-))
>
> Darryl
>

Reverse or "negative thinking"

Darryl,

Nice response explaining the LIMITATIONS of PCAS.

Eric article did and excellent job of explaining the workings and the
features of the various collision avoidance hardware available. I
think we need a follow up article explaining all of the shortfalls of
each system.

For instance, I have flown with PCAS a couple of times and it did not
work at all the way I had expected it to work. Yes, it worked, but I
had a totally wrong impression of what was going to happen.

I think a lot of pilots equip their airplanes and gliders with the
"latest and greatest" hardware and get a false sense of security.

The problem is you can't prove a negative. All of the systems will
can't assure that ALL of the aircraft have been "spotted". Just like
"see and avoid" cannot guarantee that you see everybody, I don't see
any collision avoidance system that can "see" everybody either.

The day after the Boulder incident, a guy came into the Cafe at our
airport. He flew in with a new Cirrus equipped with a Garmin 1000.
Overhearing our glider conversation, he asked a very telling question,
"Do gliders have transonders?".

He was shocked by my answer, and I was shocked by his question!!!!


Cookie

[JJ Sinclair]

Eric,
I tow with my transponder on and I'm hoping this will protect me and
my tow plane from a Boulder type scenario.
Your thoughts appreciated,
JJ

[Bob]

Somehow we all need to get transponders in our gliders.

Bob

[brianDG303[_2_]]

On Feb 12, 2:09*am, Hagbard Celine > wrote:
> When it came to the battery part of the article there was still
> nothing on an specific NiMH or LiLon *batteries. I was wondering if
> anyone has tried either of the batteries from this company:http://www.atsipowermanagement.co.uk/lynx.html10 A/H in a PS1270 size
> would be nice if it works.

I don't think either of the batteries are actually available. If I was
going to go down this road I might look to:

http://www.heatedclothing4you.com/heat/batteries.html

but those AGM (lead) batteries seem to work pretty well for me.

Brian

[JJ Sinclair]

> I tow with my transponder on and I'm hoping this will protect me and
> my tow plane from a Boulder type scenario.
> Your thoughts appreciated,
> JJ

Errrrr, that is assuming the hitter has asked for flight following or
has some kind of collision avoidance equipment.
Thanks,
JJ

[Frank Whiteley]

On Feb 12, 8:10*am, Bob > wrote:
> Somehow we all need to get transponders in our gliders.
>
> Bob

Lobby for stimulus money.

[Darryl Ramm]

On Feb 12, 8:24*am, JJ Sinclair > wrote:
> > I tow with my transponder on and I'm hoping this will protect me and
> > my tow plane from a Boulder type scenario.
> > Your thoughts appreciated,
> > JJ
>
> Errrrr, that is assuming the hitter has asked for flight following or
> has some kind of collision avoidance equipment.
> Thanks,
> JJ


Barging in on Eric's reply with another long winded post...

If the threat aircraft you are worried about are on flight following
(i.e. they have a transponder and can be seen on radar by ATC and have
bothered to actually contact ATC for flight following) then by
definition you are both likely to be in radar coverage and ATC should
be able to provide traffic advisories under flight following. Of
course that or anything else here is no guarantee of protection. Of
course, especially down low where tow planes often are, many aircraft
are not under flight following.

The other part of the question is "some kind of collision avoidance
equipment". So watcha thinking?

PCAS? - See my previous post for a warm up.

Mode S TIS? - requires both aircraft to be within coverage of a radar
with TIS support. Low level coverage (where many tow planes spend a
lot of time) may not be good depending on your proximity to the
terminal radar. e.g. out of where JJ and I fly NORCAL approach radar
out of Sacramanto has TIS support, Reno approach does not. Threat
aircraft with TIS should see us on those of us with transponders on
those long mountain tows but will have problems down low.

TCAD/TAS (e.g. L3 Skywatch or Garmin 800 series)/TCAS (jets airliners
etc.)? - should provide pretty good visibility of you, independent of
ground radar or any other ground infrastructure. Prices start $10k-
$20k for GA aircraft, so more something you find in newer aircraft.
Pretty impressive stuff but it still has limits.

ADS-B? - won't see you at all because there is no ADS-B ground
infrastructure where you fly yet (CA/NV) and few aircraft have ADS-B.
Once there is ADS-B ground infrastructure then ADS-R will relay your
SSR/transponder position to ADS-B receiver equipped aircraft. If the
radar can't see you the ADS-B equipped aircraft won't know about you.
The answer there is eventually you would add an ADS-B transmitter.
e.g. a Mode S transponder like the Trig TT21 with ADS-B over 1090ES or
in future a UAT transmitter/transceiver when suitable models become
available. The ADS-B part of the transponder operates independently of
ground Radar coverage. But one (USA unique) problem there is you will
need to be within coverage of an ADS-B ground station for ADS-R so
that your 1090ES ADS-B is retransmitted for folks with ADS-B UAT
receivers and visa-versa. But eventually that ground station coverage
is going to be pretty impressive, way more than SSR, but still it's an
issue to be aware of. ADS-B is also capable of ultimately offering
other advantages (much better long range traffic awareness/tracking,
much better tracking usable for SAR, possibly ground based monitoring
by FBOs, clubs, contest tracking etc.). This ADS-B future is one
reason that if I was buying a transponder today it would likely be a
Mode S capable of 1090ES. Which in the USA effectively currently means
it would be a Trig TT21.

FLARM? - won't see your transponder and effectively no GA aircraft in
the USA are FLARM equipped and I suspect relatively few ever would be.
If you are only concerned about glider-glider and towplane-glider
separation then FLARM is a wonderful approach but the USA never got
the start on FLARM when it should have and now ADS-B is coming which
is going to confuse this picture (and given what is happening adopting
FLARM instead of ADS-B in many places might be bad idea). But and it
is a big but -- products like PowerFLARM and TRX-1090 that combine a
FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
impressive on paper and I expect/hope to see them being used in the
USA.

And to the above add some generic issues, like -

- Pilot training/knowledge (transponder turned on, in ALT mode?
traffic awareness system turned on and the pilot known how to use it,
etc.).
- Lots of gliders in gaggles etc. may confuse a traffic awareness
system and/or the pilot
- Other non-transponder equipped aircraft in close proximity may be in
somewhat increased danger if aircraft are avoiding the transponder
equipped targets,
- etc. etc.

So while the question was about transponders in the glider and traffic
awareness systems in the threat aircraft, overall the matter is
working out which technology amongst things like transponders, ADS-B
transmitters and/or receivers, PCAS, powerFLARM type devices, etc.
make most sense for a particular situation/risk assumptions.

Just a semantic niggle but I prefer to say things like "provide or
help with traffic awareness" vs. "provide protection". But I know I
slip on this all the time as well. Oh and I don't want anybody to get
the wrong impression that technology cannot provide a hugely important
help here and the limitations like I mentioned in this thread means it
is not worth using. Human eyesight is easily fooled, visibility of
threats is easily reduced or obstructed etc. These technologies are
really useful, I just want people to think about the different choices
and their benefits and limitations and select the best technology to
help improve their flight safety.

Darryl

[Dave Nadler]

On Feb 12, 1:47*pm, Darryl Ramm > wrote:
> FLARM? - won't see your transponder and effectively no GA aircraft in
> the USA are FLARM equipped and I suspect relatively few ever would be.
> If you are only concerned *about glider-glider and towplane-glider
> separation then FLARM is a wonderful approach but the USA never got
> the start on FLARM when it should have and now ADS-B is coming which
> is going to confuse this picture (and given what is happening adopting
> FLARM instead of ADS-B in many places might be bad idea). But and it
> is a big but -- products like PowerFLARM and TRX-1090 that combine a
> FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
> impressive on paper and I expect/hope to see them being used in the
> USA.

Just to clarify Darryl's point: The FLARM unit to be offered in USA
is PowerFLARM, and they expect most people will opt for the ADS-B
receiver option. The ADS-B option listens to direct transponder
transmissions,
mode C or mode S, and also TIS-B ground-stations (which will
exist someday we hear).

Thanks Darryl !
Best Regards, Dave

[Chris Reed[_2_]]

There was a recent report in the UK press that UAVs will be permitted to
fly in Class G airspace once they are capable of autonomous collision
avoidance, and that the technology they were looking at was FLARM. I'm
sure we Brits (will) buy our UAVs from the US - might this mean that the
US military is also trialling FLARM?


Dave Nadler wrote:
> On Feb 12, 1:47 pm, Darryl Ramm > wrote:
>> FLARM? - won't see your transponder and effectively no GA aircraft in
>> the USA are FLARM equipped and I suspect relatively few ever would be.
>> If you are only concerned about glider-glider and towplane-glider
>> separation then FLARM is a wonderful approach but the USA never got
>> the start on FLARM when it should have and now ADS-B is coming which
>> is going to confuse this picture (and given what is happening adopting
>> FLARM instead of ADS-B in many places might be bad idea). But and it
>> is a big but -- products like PowerFLARM and TRX-1090 that combine a
>> FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
>> impressive on paper and I expect/hope to see them being used in the
>> USA.
>
> Just to clarify Darryl's point: The FLARM unit to be offered in USA
> is PowerFLARM, and they expect most people will opt for the ADS-B
> receiver option. The ADS-B option listens to direct transponder
> transmissions,
> mode C or mode S, and also TIS-B ground-stations (which will
> exist someday we hear).
>
> Thanks Darryl !
> Best Regards, Dave

[Darryl Ramm]

On Feb 12, 12:05*pm, Chris Reed > wrote:
> There was a recent report in the UK press that UAVs will be permitted to
> fly in Class G airspace once they are capable of autonomous collision
> avoidance, and that the technology they were looking at was FLARM. I'm
> sure we Brits (will) buy our UAVs from the US - might this mean that the
> US military is also trialling FLARM?
>
> Dave Nadler wrote:
> > On Feb 12, 1:47 pm, Darryl Ramm > wrote:
> >> FLARM? - won't see your transponder and effectively no GA aircraft in
> >> the USA are FLARM equipped and I suspect relatively few ever would be.
> >> If you are only concerned *about glider-glider and towplane-glider
> >> separation then FLARM is a wonderful approach but the USA never got
> >> the start on FLARM when it should have and now ADS-B is coming which
> >> is going to confuse this picture (and given what is happening adopting
> >> FLARM instead of ADS-B in many places might be bad idea). But and it
> >> is a big but -- products like PowerFLARM and TRX-1090 that combine a
> >> FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
> >> impressive on paper and I expect/hope to see them being used in the
> >> USA.
>
> > Just to clarify Darryl's point: The FLARM unit to be offered in USA
> > is PowerFLARM, and they expect most people will opt for the ADS-B
> > receiver option. The ADS-B option listens to direct transponder
> > transmissions,
> > mode C or mode S, and also TIS-B ground-stations (which will
> > exist someday we hear).
>
> > Thanks Darryl !
> > Best Regards, Dave
>
>

Unlikely. I think you will find that for the USA ADS-B UAT (and to a
lesser extend at the low-end 1090ES) is the twinkle in the eye of the
US military, defense/aerospace contractors, DHS and various police
forces excited about UAVs. ADS-B is much more capable of things like
extensive remote tracking, integration with ATC systems, etc. that
Flarm does not try to do. As for looking at Flarm as an interesting
early practical implementation of an automatic broadcast system I
expect many military/defense contractor types are aware of it.

Darryl

[JJ Sinclair]

On Feb 12, 10:47*am, Darryl Ramm > wrote:
> On Feb 12, 8:24*am, JJ Sinclair > wrote:
>
> > > I tow with my transponder on and I'm hoping this will protect me and
> > > my tow plane from a Boulder type scenario.
> > > Your thoughts appreciated,
> > > JJ
>
> > Errrrr, that is assuming the hitter has asked for flight following or
> > has some kind of collision avoidance equipment.
> > Thanks,
> > JJ
>
> Barging in on Eric's reply with another long winded post...
>
> If the threat aircraft you are worried about are on flight following
> (i.e. they have a transponder and can be seen on radar by ATC and have
> bothered to actually contact ATC for flight following) then by
> definition you are both likely to be in radar coverage and ATC should
> be able to provide traffic advisories under flight following. Of
> course that or anything else here is no guarantee of protection. Of
> course, especially down low where tow planes often are, many aircraft
> are not under flight following.
>
> The other part of the question is "some kind of collision avoidance
> equipment". So watcha thinking?
>
> PCAS? - See my previous post for a warm up.
>
> Mode S TIS? - requires both aircraft to be within coverage of a radar
> with TIS support. Low level coverage (where many tow planes spend a
> lot of time) may not be good depending on your proximity to the
> terminal radar. e.g. out of where JJ and I fly NORCAL approach radar
> out of Sacramanto has TIS support, Reno approach does not. Threat
> aircraft with TIS should see us on those of us with transponders on
> those long mountain tows but will have problems down low.
>
> TCAD/TAS (e.g. L3 Skywatch or Garmin 800 series)/TCAS (jets airliners
> etc.)? - should provide pretty good visibility of you, independent of
> ground radar or any other ground infrastructure. Prices start $10k-
> $20k for GA aircraft, so more something you find in newer aircraft.
> Pretty impressive stuff but it still has limits.
>
> ADS-B? - won't see you at all because there is no ADS-B ground
> infrastructure where you fly yet (CA/NV) and few aircraft have ADS-B.
> Once there is ADS-B ground infrastructure then ADS-R will relay your
> SSR/transponder position to ADS-B receiver equipped aircraft. If the
> radar can't see you the ADS-B equipped aircraft won't know about you.
> The answer there is eventually you would add an ADS-B transmitter.
> e.g. a Mode S transponder like the Trig TT21 with ADS-B over 1090ES or
> in future a UAT transmitter/transceiver when suitable models become
> available. The ADS-B part of the transponder operates independently of
> ground Radar coverage. But one (USA unique) problem there is you will
> need to be within coverage of an ADS-B ground station for ADS-R so
> that your 1090ES ADS-B is retransmitted for folks with ADS-B UAT
> receivers and visa-versa. But eventually that ground station coverage
> is going to be pretty impressive, way more than SSR, but still it's an
> issue to be aware of. ADS-B is also capable of ultimately offering
> other advantages (much better long range traffic awareness/tracking,
> much better tracking usable for SAR, possibly ground based monitoring
> by FBOs, clubs, contest tracking etc.). This ADS-B future is one
> reason that if I was buying a transponder today it would likely be a
> Mode S capable of 1090ES. Which in the USA effectively currently means
> it would be a Trig TT21.
>
> FLARM? - won't see your transponder and effectively no GA aircraft in
> the USA are FLARM equipped and I suspect relatively few ever would be.
> If you are only concerned *about glider-glider and towplane-glider
> separation then FLARM is a wonderful approach but the USA never got
> the start on FLARM when it should have and now ADS-B is coming which
> is going to confuse this picture (and given what is happening adopting
> FLARM instead of ADS-B in many places might be bad idea). But and it
> is a big but -- products like PowerFLARM and TRX-1090 that combine a
> FLARM transceiver, ADS-B 1090ES receiver and a PCAS receiver look very
> impressive on paper and I expect/hope to see them being used in the
> USA.
>
> And to the above add some generic issues, like -
>
> - Pilot training/knowledge (transponder turned on, in ALT mode?
> traffic awareness system turned on and the pilot known how to use it,
> etc.).
> - Lots of gliders in gaggles etc. may confuse a traffic awareness
> system and/or the pilot
> - Other non-transponder equipped aircraft in close proximity may be in
> somewhat increased danger if aircraft are avoiding the transponder
> equipped targets,
> - etc. etc.
>
> So while the question was about transponders in the glider and traffic
> awareness systems in the threat aircraft, overall the matter is
> working out which technology amongst things like transponders, ADS-B
> transmitters and/or receivers, PCAS, powerFLARM type devices, etc.
> make most sense for a particular situation/risk assumptions.
>
> Just a semantic niggle but I prefer to say things like "provide or
> help with traffic awareness" vs. "provide protection". But I know I
> slip on this all the time as well. Oh and I don't want anybody to get
> the wrong impression that technology cannot provide a hugely important
> help here and the limitations like I mentioned in this thread means it
> is not worth using. Human eyesight is easily fooled, visibility of
> threats is easily reduced or obstructed etc. These technologies are
> really useful, I just want people to think about the different choices
> and their benefits and limitations and select the best technology to
> help improve their flight safety.
>
> Darryl

Well, that's comforting, I think? Guess I'll keep my mark-1 eyeball
greased up. You know I (we) almost hit a glider while on tow at
Montague at 1500 feet. I saw him and figured he was a good mile away
when suddenly he was right on us! The tow pilot kicked right rudder as
he passed and then he was headed straight for my left wing. I rolled
90 degrees left and he missed me by maybe 5 feet! The RC sailplane
guys were having their nationals and we almost hit a 12 foot white
sailpland model. Seems our tow route took us past their first turn
point about 5 miles north on Montague.

Turn on the radio and use it!
Turn on the Transponder and talk to center when necessary.........we
do that a lot around Reno.
Turn on the PCAS and monitor it.
Keep your head on a swivel..........outside the cockpit.
Cheers,
JJ

[Eric Greenwell]

JJ Sinclair wrote:
> Eric,
> I tow with my transponder on and I'm hoping this will protect me and
> my tow plane from a Boulder type scenario.
> Your thoughts appreciated,
> JJ
>
It could help, if you are towing where radar can reach you, and the
other aircraft has a PCAS or has flight following from ATC. If radar
does reach you, then having your own PCAS will help, too.

It _will_ help if a TCAS equipped aircraft approaches, because they
don't need radar or ATC contact for TCAS to work.

It might be appropriate to inform the local Approach people when you
begin towing, so they can pass on the info to pilots they talk to.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl.com/yg76qo9

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

[Eric Greenwell]

Frank Whiteley wrote:
> On Feb 12, 8:10 am, Bob > wrote:
>
>> Somehow we all need to get transponders in our gliders.
>>
>> Bob
>>
>
> Lobby for stimulus money.
>
It worked for New Zealand. About 10 years ago, they got transponders in
every glider because the government bought them for the gliders. The
AOPA has made some proposals along that line for fitting ADS-B to GA
aircraft. I have no idea if it's worth pursuing.

NZ pilots, don't be bashful about correcting/adding details.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl.com/yg76qo9

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

[Frank Whiteley]

> Well, that's comforting, I think? Guess I'll keep my mark-1 eyeball
> greased up. You know I (we) almost hit a glider while on tow at
> Montague at 1500 feet. I saw him and figured he was a good mile away
> when suddenly he was right on us! The tow pilot kicked right rudder as
> he passed and then he was headed straight for my left wing. I rolled
> 90 degrees left and he missed me by maybe 5 feet! The RC sailplane
> guys were having their nationals and we almost hit a 12 foot white
> sailpland model. Seems our tow route took us past their first turn
> point about 5 miles north on Montague.
>
> Turn on the radio and use it!
> Turn on the Transponder and talk to center when necessary.........we
> do that a lot around Reno.
> Turn on the PCAS and monitor it.
> Keep your head on a swivel..........outside the cockpit.
> Cheers,
> JJ

I guess that means read the NOTAMs also. We have large amateur rocket
activity a few miles east of our glider port at times.

Frank Whiteley

[Tony V]

Darryl Ramm wrote:

> If the threat aircraft you are worried about are on flight following
> (i.e. they have a transponder and can be seen on radar by ATC and have
> bothered to actually contact ATC for flight following) then by
> definition you are both likely to be in radar coverage and ATC should
> be able to provide traffic advisories under flight following.

The above phrase "should be able to" is correct. ATC in the U.S. is only
required to provide VFR traffic advisories on a "workload permitting"
basis. If the controller has his hands full with IFR traffic, you lose.
Remember that lots of people file IFR on perfectly good VFR days.

Tony

[Eric Greenwell]

Hagbard Celine wrote:
> When it came to the battery part of the article there was still
> nothing on an specific NiMH or LiLon batteries. I was wondering if
> anyone has tried either of the batteries from this company:
> http://www.atsipowermanagement.co.uk/lynx.html 10 A/H in a PS1270 size
> would be nice if it works.
>
It looks like it would be a good choice, but I was unable to find a
supplier or cost. You would have to buy it's charger, also, so the total
cost for this "aviation" battery might be breathtaking. Let us know if
you do find a supplier. It still might be a good option for some people,
even if it is costly.

If you use a Trig TT21, the power drain should be low enough that a 4 to
5 ah battery would be adequate - not ideal, but adequate for 8-10 hour
flights in cold weather. That size is small and light enough, almost
everyone should be able to mount a battery just for the transponder, if
needed. Pilot reports on the Trig power consumption, anyone?

On Page 15 of the article, I detail why I do not recommend Li batteries
for gliders. Here's what I say:

" IF you can find a 12 to 14 volt, commercially produced lithium battery
pack, AND rated for operation to 18,000’ (or your
highest operating altitude) AND with a matching charger, THEN you might
consider using it. I couldn’t find any that met all these conditions
(Dec. 2007), the best matches I could find cost several hundred dollars,
and they wouldn’t fit a standard glider battery mounting."

If you use a battery ONLY for the Trig TT21, you don't need to have a 12
volt battery. It could be up to 30 volts. That relaxed voltage
specification might make it easier to find a suitable nimh or Li
battery. Still, the standard lead acid battery works well, it's cheap,
it's easy to charge, and it's safe. The weight isn't really an issue in
most cases, given the 500+ pound weight of a glider.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Jan/2010" also ADS-B, PCAS, Flarm tinyurl.com/yg76qo9

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

[Eric Greenwell]

In response to the questions about batteries and couple outdated remarks
Paul Remde caught, there is a new update "B" available from:

* http://tinyurl.com/ylbu7a9

*Besides the updates, it now uses vertical lines to the left of any
paragraph with significant changes to make it easier to spot them.

It will also be on the soaringsafety.org website as soon as they can
update it (might be a few days)

Eric Greenwell wrote:
> This article, originally in Soaring (Feb 2002) was updated recently to
> include information on the Trig TT21 transponder.
--

Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes 2010B" also ADS-B, PCAS, Flarm *http://tinyurl.com/ylbu7a9*

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

[Mike Schumann]

On 2/12/2010 12:18 PM, Frank Whiteley wrote:
> On Feb 12, 8:10 am, > wrote:
>> Somehow we all need to get transponders in our gliders.
>>
>> Bob
>
> Lobby for stimulus money.
We don't need money. What is needed is for the FAA to permit the
commercialization of MITRE's low cost ADS-B transceiver. We are making
SLOW progress on that front. The FAA & SSA are going to do a
demonstration project this summer in the DC area.

If we can get ADS-B transceivers to be available at the same price point
as FLARM in Europe, we will see a similar explosion in deployment rates,
which will make soaring (and GA) a much safer environment.

--
Mike Schumann