Transponders

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.

Mike Raisler wrote:

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.


Ok, but the advice emitted by the TCAS in the other aircraft is based on the
assumption that the glider will keep its flying level and this is not true.

"Robert Ehrlich" wrote:
Mike Raisler wrote:

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.


Ok, but the advice emitted by the TCAS in the other aircraft is based on
the
assumption that the glider will keep its flying level and this is not
true.

It is far better than no warning at all. The pilots of the TCAS equipped
aircraft will at least get their heads out of the cockpit and take a look
out of the windows.

Marc

Robert Ehrlich wrote:

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.



Ok, but the advice emitted by the TCAS in the other aircraft is based on the
assumption that the glider will keep its flying level and this is not true.

It's my understanding that the conflict resolution algorithm is based on
much more realistic assumptions, so that climbing and turning flight of
the potential threats is included. The simple assumption of straight
flight might have been used in the very beginning, but no longer. If you
have a recent reference that suggests otherwise, I'd like to know about it.

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Eric Greenwell
Washington State
USA

Eric Greenwell skrev den Tue, 03 Feb 2004
12:15:57 -0800:
It's my understanding that the conflict resolution algorithm is based on
much more realistic assumptions, so that climbing and turning flight of
the potential threats is included. The simple assumption of straight
flight might have been used in the very beginning, but no longer. If you
have a recent reference that suggests otherwise, I'd like to know about
it.

The algorithm is to look at a number of consecutive returns to determine a
rate of closure and then divide the distance with this rate to give a
'tau' value, of time to impact should there be a collision. When this
value goes below an [altitude dependant] threshold, you have a traffic
advisory. Another lower [also altitude dependant] threshold, and the TCAS
begins working on a resolution advisory.

In other words, more or less straight but not level flight is assumed.

Cheers,
Fred

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.