Transponders

The situation isn't nearly so gloomy!

Mark James Boyd wrote:
From what I can gather, the low-power transponders are 400mA
and encoder 200mA at about 12 volts.

My Becker and ACK encoder ~ 410 ma with no replies, and less than 500 ma
even in southern California airspace. A 5 hour flight is 2.5 amphour,
leaving lots of juice for the other instruments on the typical 7 ah battery.


The microfilm superthin solar panels about 1 foot square (12" by 12")
advertise 600mA at about 12 volts.

Sadly, the solar panels in my experience don't put out rated power
on typical days, with less than ideal sun angles (maybe really only
putting out 25%).

Put two on! But even one, with your assumption, means the battery has to
supply 1.7 ah to the battery, leaving ~ 5 ah in the battery for other
purposes. With two supplying 300 ma, the net transponder usage is only 1 ah!


Also, I suspect transponders underrate their power consumption,
and if flown in high jet traffic areas (where they get
pinged by ATC and the jets), probably consume quite a bit more.

Not true for the Becker. Ask a Microair owner about it's consumption.

So really one might be looking at 8 square feet of solar
array just for a transponder! Maybe a little hard to
implement on a glider without using the wing surfaces,
and the caveats that entails...

The Strobl panels used by the German manufacturers are very efficient
(http://www.strobl-solar.de/ - use the Google translation tools) and can
supply enough with less than 2 square feet. The disadvantage is the
cost, so most people would probably opt for another, or bigger, battery.


Well, it was a nice thought...

It _is_ a nice thought! People are doing it - it works!

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

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.

On Sat, 24 Jan 2004 14:57:28 -0800, Eric Greenwell
wrote:

Mike Borgelt wrote:


go to www.arinc.com and search for TCAS. You will find a very useful
paper describing the characteristics of the TCAS system.

After describing how wonderful it all is note the sudden disclaimer at
the end.

Could you be more specific, like a title? I get 32 hits and the few I
checked don't seem to be it.


Eric,

The file you want is tcas.pdf
It is about 500k. If you can't find it I'll send it to you.

Mike Borgelt

Mike Borgelt wrote:
On Sat, 24 Jan 2004 14:57:28 -0800, Eric Greenwell
wrote:


Mike Borgelt wrote:


go to www.arinc.com and search for TCAS. You will find a very useful
paper describing the characteristics of the TCAS system.

After describing how wonderful it all is note the sudden disclaimer at
the end.

Could you be more specific, like a title? I get 32 hits and the few I
checked don't seem to be it.



Eric,

The file you want is tcas.pdf
It is about 500k. If you can't find it I'll send it to you.

Please send it - I can't find it. Thanks.
--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

A number of times I have switched on my transponder
and called for a clearance but ATC have not been able
to see me. I can see my transponder being interogated,
I have good battery power, everything seems to be working
but ATC still can't see me. This has happened to a
number of pilots I know.

So next time you set and forget... don't assume your
transponder is actually working.

If you don't call for a clearance you have no idea
whether you are transmitting or not.



At 17:00 23 January 2004, Bob Kuykendall wrote:
Earlier, Ben Flewett wrote:

...Once you agree to put transponders
in gliders you are obliged to use them
and they are a pain in the ass...

If that's on the basis of your personal experience,
I'd be inclined to
check if maybe you mounted the antenna the wrong way
up.

Where I fly, there are airliners. We have a letter
of agreement that
allows us one squawk code. No talking to Center; it's
just set and
forget. And, yes, there are officially rules about
always using the
transponder if it is available. Uh huh. Right.

Bob K.

Kirk,

We use transponders in a very different way in NZ.
I consider them a pain in the ass but many NZ pilots
would disagree. This is a very big generalisation
but... the pilots that don't mind using transponders
are more focused on flying rather than soaring... if
you know what I mean.

However, as I mentioned in an earlier posting... If
you don't call for a clearance there is a chance your
transponder is not transmitting correctly despite what
it may be telling you. If I am flying in the same
airspace as commercial jets I want to know for sure
that ATC can see me.

For me the single biggest risk to our sport is the
possiblity of a commercial airliner being brought down
by a glider. If this happens gliding will loose -
it will not matter who is at fault.

Ben.



At 15:30 23 January 2004, Kirk Stant wrote:
Ben Flewett wrote in message news:...
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

Ben Flewett wrote:

A number of times I have switched on my transponder
and called for a clearance but ATC have not been able
to see me. I can see my transponder being interogated,
I have good battery power, everything seems to be working
but ATC still can't see me. This has happened to a
number of pilots I know.

Checking ocasionally is a good idea. In the US, you don't have to ask
for a clearance to determine this, but just contact the local tower or
approach guys and ask if they can see you. Actually getting the system
checked as required every 24 months is also a good idea.
--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Ben Flewett wrote:
A number of times I have switched on my transponder
and called for a clearance but ATC have not been able
to see me. I can see my transponder being interogated,
I have good battery power, everything seems to be working
but ATC still can't see me. This has happened to a
number of pilots I know.

If you don't call for a clearance you have no idea
whether you are transmitting or not.

Man, if I had a nickel for every time ATC said they didn't have
me but the airliner 10 miles out had me plain as
day, I'd have some nickels!

Too low, in line with another transponder, receiver too
far away, etc. If I let an ATC guy convince me to swap out
a $1000+ part, I'd get his avionics repair certificate number
first... ;(

Ben Flewett wrote:

A number of times I have switched on my transponder
and called for a clearance but ATC have not been able
to see me. I can see my transponder being interogated,
I have good battery power, everything seems to be working
but ATC still can't see me. This has happened to a
number of pilots I know.

Their have been similar cases to this in our club. It turns out that ATC
at Cape Town International had set their radar to filter out anything
moving slower than 40kt (ground speed). This I believe to filter out
stationery aircraft on the ground taxiing etc.

Gliders in wave simply disappeared off the radar screens, which did not
help anybody ...


Ian

Ian Forbes wrote:
Ben Flewett wrote:


A number of times I have switched on my transponder
and called for a clearance but ATC have not been able
to see me. I can see my transponder being interogated,
I have good battery power, everything seems to be working
but ATC still can't see me. This has happened to a
number of pilots I know.


Their have been similar cases to this in our club. It turns out that ATC
at Cape Town International had set their radar to filter out anything
moving slower than 40kt (ground speed). This I believe to filter out
stationery aircraft on the ground taxiing etc.

Gliders in wave simply disappeared off the radar screens, which did not
help anybody ...

Did the gliders have Mode C?

Is the radar for Cape Town just for the airport, or is it intended to
cover a much larger area?

In our area airport radar and the higher altitude radars are separate,
so even if the airport radar folks blanked slow moving traffic, Center
radar would see it.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA