"jettester" wrote in message
oups.com...
5Z wrote:
With all this discussion going on now, maybe someone with some
knowledge or experience could enlighten us on the consequences of 10 or
more sailplanes in a tight gaglge all squawking the same info. Will
ATC see them all? Or will interference and/or filtering software at
ATC make some or all of them invisible?

Will TCAS be able to make sense of all these close together
transponders?

Remember, the typical application of the transponder is to separate
traffic, so it is very unusual to have two (in our case 5, 10 or even
40) or more within 1,000' of each other. Can furrent technology deal
with that, or will equipping all sailplanes create more problems than
it solves?

Thanks

-Tom

Tom;
I am a FAA Test Pilot who is authorized to test Transponders in new
aircraft... I do this for a living. I also was qualified as a Hawker
800XP test pilot.

Bottom Line - Transponders are NOT the answer! Try putting one of
these new LED Strobe Lights on the top of your Fin instead.

#1. Transponders would not solve the mid air problem unless you were
the only one in close proximity to the attacking aircraft. Typically,
they set MTI (moving target indicator) to above 60K or higher
(especially if near a large amount of highway ground traffic), so once
you start thermalling they lose you unless you are given a discrete
squawk other than 1200 (for non participating VFR Traffic)

#2. If multiple gliders (or aircraft) are in the vicinity all
squawking 1200, ATC could not tell one from the other. Mode C (if you
have it) reports altitude, yet if the climb or descent rate is large
(let's say greater than 1500fpm) their equipment typically faults you
off the scope and does not report your altitude. Once again unless you
are given a discrete squawk other than 1200 (VFR traffic).

#3. If multiple gliders (or other aircraft) are in the same proximity
on closing trajectories, the ATC system will issue warnings to the
controller, that he must issue to the offending aircraft, to try to
prevent them from colliding.... Unless you are in direct communication
with ATC, they will probably get extremely miffed (read.. ask you to
call them when you land, and they will probably find you!!) because
they are spending more time trying to cancel these warnings to control
other "participating" aircraft.

#4. MODE S transponders have a discrete ID code embedded in the
transponder that is supposed to be set to your aircraft registry ID
(look on the FAA website for your aircraft registry information and you
will find that ID for your aircraft). Mode S talks to other mode S
equipped transponders, and is typically used to provide TCAS (Traffic
Collision Avoidance System) information to issue the advisories to each
aircraft. If you have this feature, and were to pullup rapidly with
another mode S aircraft overhead, it could set off his traffic warning
system.

#5. I have flown in wave with a transponder equipped glider, yet I was
talking with ATC and had clearance into the window. Always, conditions
were VMC, even though operating in Class A airspace under an IFR Flight
Plan.

#6. Transponders are expensive... DO NOT solve the "see and avoid"
problem.. can potentially really mess ATC up if you are not in direct
contact with them.. and in the case of the Hawker midair..... would not
have prevented the collision.

Jettester (UP)


Thank you.

Al G