Transponders

Marc Ramsey wrote:

... It did not examine whether airborne collision
avoidance systems would continue to provide warnings when confronted by
such situations.
...

The only such system I have heard about is TCAS. As far as I know
this system is not available on gliders, only on big airplanes
carrying passengers or military ones. It should emit hints to the
pilot for avoiding the collision based on altitude information, assuming
that the other aircraft is going to fly at a constant altitude, or
to follow the hint of its own TCAS, and neither is true for a glider.

Robert Ehrlich wrote:
The only such system I have heard about is TCAS. As far as I know
this system is not available on gliders, only on big airplanes
carrying passengers or military ones. It should emit hints to the
pilot for avoiding the collision based on altitude information, assuming
that the other aircraft is going to fly at a constant altitude, or
to follow the hint of its own TCAS, and neither is true for a glider.

TCAS/ACAS detects nearby transponder equipped aircraft. In the US and
western Europe, almost all aircraft larger than small twins now have
them. They will provide useful warning of the presence of a nearby mode
C equipped glider, whether or not the glider is flying straight and level.

Marc

Robert Ehrlich wrote:
Marc Ramsey wrote:

... It did not examine whether airborne collision
avoidance systems would continue to provide warnings when confronted by
such situations.
...

The only such system I have heard about is TCAS. As far as I know
this system is not available on gliders, only on big airplanes
carrying passengers or military ones. It should emit hints to the

I've seen a $20,000 version of TCAS, with a graphic display and
altitude displayed, in an acquantence's 182. It seemed a little
big for a glider (display the size of a Garmin 430). And
my goodness I can only imagine the power consumption!

TCAS installed on all transport category aircraft can "read" mode "c" or "s"
and determine if a climb or descent is needed to avoid the other aircraft.
The glider does not need to have TCAS installed, only a transponder, in
order for the other aircafts TCAS system alert for an avoidance manuever.


"Robert Ehrlich" wrote in message
...
Marc Ramsey wrote:

... It did not examine whether airborne collision
avoidance systems would continue to provide warnings when confronted by
such situations.
...

The only such system I have heard about is TCAS. As far as I know
this system is not available on gliders, only on big airplanes
carrying passengers or military ones. It should emit hints to the
pilot for avoiding the collision based on altitude information, assuming
that the other aircraft is going to fly at a constant altitude, or
to follow the hint of its own TCAS, and neither is true for a glider.

my experience is, that ATCs do not like glider pilots
as soon as they find out, that you cannot keep your
flight level.
In central Europe I had a transponder in the glider,
to get permission to cross some controlled corridors.
I mostly got permission to cross the airspace with
the condition of keeping flight level! A reply of not
being able to keep flight level invertet mostly the
permission into refusal.
The trick was then to enter the airspace first and then
request for sinking to flightlevel (-2FL for the 20km).
But the ATC never liked you for doing that!!

I think Transponder requirement is only virtually
increasing safety. You accept to install transponders
and as a thank you, they will steal you some more
airspace which has been free for VFR before!

Chris


"Robert Ehrlich" wrote in message
...
Chris Nicholas wrote:
An experiment in the french Alps made with a group of tow planes
mimicking glider flight, i.e. circling together from time to time has
shown that transponders, except in mode S, may not be very useful in
gliders. As soon as 2 or more gliders are close together, e.g. circling
in the same thermal of working together the same ridge, they are hit
simultaneaously by the radar beam and generate simultaneaously their
responses, which results in both interfering and nothing useful
received at ATC. I had the chance of having one of the engineers
involved in the experiment as a passenger last September and he confirmed
this. In mode S, as each transponder is specifically adressable,
this mess will probably not occur, a new experiment using them is
planned.

Chris Nicholas wrote:

Mil80c , another point you need to be
aware of;

Many gliders, e.g. mine (a Ka6E), have neither panel space for a
transponder nor capability of carrying any more weight for the extra
batteries - I am already on max AUW, on a CofA which has already been
extended as far as it can be - I am 208 pounds with a parachute, and
there are plenty of heavier pilots than that.

If a new generation of lightweight, low power transponders emerges (the
UK CAA has persuaded one manufacturer to build a prototype which tested
OK), and if ICAO accept 20 w output instead of 100+, and if the thing is
taken to commercial production, and if it can come with an option of a
small remote control panel I could strap to my knee, with the larger
piece and battery going into the stowage behind the pilot's seat, and if
I can lose enought weight to compensate for it, then it might be viable.

Transponder + encoder = 1 kg
7 amphour battery = 2.3 kg
ant and cable = .4 kg
mounting all of it = .5 kg
TOTAL = 4.2 kg or 9.3 pounds

If this is what is keeping you from installing a transponder that you
think you need, I suggest you take another look at your priorities. Put
in the transponder by - losing 10 pounds; getting a lighter parachute;
removing something from the panel; flying 10 pounds overgross and cut
your critical speeds a couple of knots. Or, if you want to spend about
$600-700 more, get the Filser Mode S when it's available and shave off a
couple pounds using a smaller battery and no external encoder.
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Eric Greenwell
Washington State
USA

Eric, my point was - and remains - that package and weight are issues
which should not be overlooked.

Most of your suggestions are not acceptable - my panel is full of things
I want, I have about as light a parachute as I know of, and flying
outside the max AUW is a no-no for insurance, CofA, and club rules
purposes. Those might not feature in your priority list, but they do
for a lot of other people. Saying I could lose weight is not very
relevant - probably most of us could - but at the margin there must be
some people for whom another 9 pounds is a diet too far.

Of course, I could go and spend 20k, 40k, or 60k on a bigger glider as
well as the several thousand k on a Mode S transponder etc.. If it were
the only way to fly, I would have to look at that. Until it is
mandatory, for many people (not just me, the original enquirer wanted to
know the general issues AIUI) that would not be an option.

And in priority lists, avoiding being killed has several other dangers
more prevalent than collision with airliners, judging by the accident
statistics.

I am not one of those determined never to use transponders. As it
happens, I can see the day coming when I will want one for my sort of
flying in the place I do it, and I will have to solve the
cost/package/weight issues then - but we are not yet there. I hope the
technology then available will make it easier - but I am not holding my
breath, as I said.

Regards - Chris N.

Chris Nicholas wrote:

Eric, my point was - and remains - that package and weight are issues
which should not be overlooked.

True, especially if it involves a battery, the majority of the weight in
the installation. It must be properly installed and accounted for in the
W&B. The rest of the items aren't a problem.

snip

And in priority lists, avoiding being killed has several other dangers
more prevalent than collision with airliners, judging by the accident
statistics.

Part of the reason is a lot of pilots in high risk areas use
transponders. We'll never know how many collisions are avoided because
of this, of course. Your situation sounds like it isn't in a high risk area.


I am not one of those determined never to use transponders. As it
happens, I can see the day coming when I will want one for my sort of
flying in the place I do it, and I will have to solve the
cost/package/weight issues then - but we are not yet there. I hope the
technology then available will make it easier - but I am not holding my
breath, as I said.

The glacial pace of change is disappointing. It took a _long_ time for
the small Microair and Becker transponders to actually hit the shelves,
and the Filser has been a mirage for even longer. It looks like it will
actually be available this year! So, something so very different, like a
low power portable unit you can stick to the canopy with a suction cup,
is likely years away.

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Eric Greenwell
Washington State
USA

There are lots of excellent reasons for not requiring
gliders to carry transponders but this study seems
flimsy. In NZ we often have groups of gliders flying
together whilst using transponders - no problem.

The main reasons for not requiring gliders to carry
transponders a

- if airspace is managed well they are not required
in most areas. The real problem is that the groups
that draw the lines on the maps give the commercial
airlines more airspace than is required. For example,
Auckland (NZ) airport has more airspace around it than
Heathrow.

- as a glider pilot I don’t want to spend my day listening
to commercial pilots talking to ATC all day. I prefer
to have the radio tuned to a gliding frequency or off.

- most (but not all) controllers don’t understand how
gliders operate. The glider pilot is often required
to provide training to controllers whilst trying to
fly their glider. I don’t like having to do this…
“no, I am a glider which means I have no engine and
thus I cannot maintain 3000ft”.

- most glider pilots (including me) are not commercial
pilots and are not practiced at talking to ATC. Controllers
are used to speaking to commercial pilots and often
become frustrated with amateur glider pilots. The
also become frustrated with the unpredictable flight
path of gliders.

Once you agree to put transponders in gliders you are
obliged to use them and they are a pain in the ass.
If you only give commercial operators the airspace
they need there should be plenty left over for gliders.



At 18:36 22 January 2004, Marc Ramsey wrote:
Robert Ehrlich wrote:
An experiment in the french Alps made with a group
of tow planes
mimicking glider flight, i.e. circling together from
time to time has
shown that transponders, except in mode S, may not
be very useful in
gliders. As soon as 2 or more gliders are close together,
e.g. circling
in the same thermal of working together the same ridge,
they are hit
simultaneaously by the radar beam and generate simultaneaously
their
responses, which results in both interfering and nothing
useful
received at ATC. I had the chance of having one of
the engineers
involved in the experiment as a passenger last September
and he confirmed
this. In mode S, as each transponder is specifically
adressable,
this mess will probably not occur, a new experiment
using them is
planned.

This study is sometimes cited as an excuse to put off
installation of
transponders until inexpensive mode S transponders
are available. My
take on it is that it addressed a fairly narrow concern,
the possible
inability of ATC to properly discern a group of thermalling
mode C
equipped gliders. It did not examine whether airborne
collision
avoidance systems would continue to provide warnings
when confronted by
such situations.

The times when I've been surprised by the close approach
of larger
aircraft have been while cruising between thermals,
when I'm generally
alone or at a fair distance from other gliders. While
thermalling, I
have a view of pretty much the entire sky, and I have
a much better
chance of seeing approaching traffic in plenty of time
to avoid it.

Marc

Ben Flewett wrote in message ...
There are lots of excellent reasons for not requiring
gliders to carry transponders but this study seems
flimsy. In NZ we often have groups of gliders flying
together whilst using transponders - no problem.

As I see it (and this is for the Western US, and may not apply in NZ
or the UK, etc) there are really only two reasons for not carrying a
transponder: No place to put it in the glider (I've been trying to
figure out where to install one in my LS6 (small panel), it will take
a complete redo of the panel to squeeze it in; and cost - as soon as I
win the lottery (or get REALLY scared by an airliner) I will probably
get one.

The main reasons for not requiring gliders to carry
transponders a

- if airspace is managed well they are not required
in most areas. The real problem is that the groups
that draw the lines on the maps give the commercial
airlines more airspace than is required. For example,
Auckland (NZ) airport has more airspace around it than
Heathrow.

If you fly away from airliners, or airways, then the midair risk is
obviously low. I fly right next to the Phoenix Class B and share
airspace with a lot of traffic. I'm still in Class E, so a
transponder isn't required and I'm not talking to ATC, but still it
would be nice to be "seen" by any TCAS-equipped planes in the
vicinity, especially when cruising (i.e. invisible) at high altitude
(cloudbase above 18000' is not uncommon out here).

- as a glider pilot I don?t want to spend my day listening
to commercial pilots talking to ATC all day. I prefer
to have the radio tuned to a gliding frequency or off.

Same here, and since I'm VFR in Class E airspace, the only time I talk
to ATC is when I think it may help - like during the week near a busy
military base. Then I let them know where I am, and the controllers
have always been very receptive - vectoring the fighters around me if
necessary. Having a transponder would make it easier for ATC to track
me, and many fighters could see me as well with their systems. It
doesn't mean I would have to talk to them more. Is it different in
NZ? (aside from no fighters - a shame about your A-4s and MB-339s!)

- most (but not all) controllers don?t understand how
gliders operate. The glider pilot is often required
to provide training to controllers whilst trying to
fly their glider. I don?t like having to do this?
?no, I am a glider which means I have no engine and
thus I cannot maintain 3000ft?.

Again, just having a transponder doesn't mean you have to talk to ATC
if VFR, it means ATC will see you and know you are VFR (squawking
1200) and let other traffic know you are there. If you do decide to
talk to ATC, it's that much easier for them to locate you. And the
ATC controller is not controlling you, so it isn't your concern if he
doesn't understand gliders - it's his, since his responsibility it to
protect the airplanes that he is "controlling"; those on IFR
flightplans in his airspace. Trust me, he will appreciate any
"training" you can give him! (thinks - invite local ATC for a glider
ride - many of them are pilots anyway and would jump at the chance!).

- most glider pilots (including me) are not commercial
pilots and are not practiced at talking to ATC. Controllers
are used to speaking to commercial pilots and often
become frustrated with amateur glider pilots. The
also become frustrated with the unpredictable flight
path of gliders.

C'mon, if stinkpot student Cezzna pilots can do it, even glider
guiders can learn to speak ATC! Try it, if you step on your johnson
you can always give your buddy's identification and turn off the
radio! And at the speeds we go, to ATC we aren't unpredictable, we
are parked!

Once you agree to put transponders in gliders you are
obliged to use them and they are a pain in the ass.
If you only give commercial operators the airspace
they need there should be plenty left over for gliders.

How are they a pain in the ass? Put in the extra battery, turn it on
when you takeoff, turn it off when you land, take out and charge the
extra battery. Again, this may only apply to the US, but having a
transponder doesn't mean you have to talk to ATC. It means that when
you do want ATC to know where you are, they will see you, and that
some airplanes (those equipped with TCAS or similar systems) will have
a much better chance of seeing and avoiding you. If you fly (location
or altitude) where there is little commercial, business, or military
traffic, a transponder will probably not help much, since most small
planes don't have a TCAS-like capability.

Just like most safety issues, the is a cost and risk tradeoff. Some
day (unfortunately, probably due to a bad glider-airliner midair),
transponders will probably be mandated, probably within certain
altitudes (say, above 10,000ft within 50 miles of Class B and C, for
example, with no exceptions). When that happens, we will have to
solve the problem.

Cheers,

Kirk