Many transponders in close proximity

Ha? The Hawker TCAS would have not detect a mode c transponder on a
collision course at 16,000ft, even if in a gaggle and sqwawking 1200?
(we sqwawk 0440 at this area though).

Ramy

jettester wrote:
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)

Ya I'm pretty uncertain now re the take home message for those of us with
mode C installed already. I thought that it was a given that traffic with
TCAS were seeing me and that center/approach could also and vector traffic
around me. After this thread I 'm not feeling froggy about any of this. In
Phoenix and most other places I fly I have been squawking 1200 (Ely,
Moriarty) but are you guys saying that I will be ignored by ground radar due
to filtering for airspeed and by TCAS for 1200???? Glad I spent the $2000.
It all seems inane to me that we go to the effort to be seen and our reward
is being "filtered out" because some moron thinks we aren't a real threat.

Casey Lenox
KC
Phoenix

Kilo Charlie wrote:
Ya I'm pretty uncertain now re the take home message for those of us with
mode C installed already. I thought that it was a given that traffic with
TCAS were seeing me and that center/approach could also and vector traffic
around me. After this thread I 'm not feeling froggy about any of this. In
Phoenix and most other places I fly I have been squawking 1200 (Ely,
Moriarty) but are you guys saying that I will be ignored by ground radar due
to filtering for airspeed and by TCAS for 1200???? Glad I spent the $2000.
It all seems inane to me that we go to the effort to be seen and our reward
is being "filtered out" because some moron thinks we aren't a real threat.

You aren't being filtered out by airspeed or code. Read the posting by
Billy Hill. Your transponder is being seen by ATC, the airliner TCAS,
and everyone with a TPAS unit, so I think your $2000 was a good value
(that's what my Becker cost me, too). We still have to worry about all
the other gliders (even those with a transponder, because I don't have a
TPAS unit yet), and some/many of the small airplanes, too.


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

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

You aren't being filtered out by airspeed or code. Read the posting by
Billy Hill. Your transponder is being seen by ATC, the airliner TCAS, and
everyone with a TPAS unit, so I think your $2000 was a good value (that's
what my Becker cost me, too). We still have to worry about all the other
gliders (even those with a transponder, because I don't have a TPAS unit
yet), and some/many of the small airplanes, too.

Eric Greenwell - Washington State, USA

Hmm.....well maybe you missed this above from jettester Eric or he's
incorrect.....

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).

I also have a Becker and will continue to believe that its better than
nothing......

KC

Kilo Charlie wrote:
After this thread I 'm not feeling froggy about any of this. In
Phoenix and most other places I fly I have been squawking 1200 (Ely,
Moriarty) but are you guys saying that I will be ignored by ground radar due
to filtering for airspeed and by TCAS for 1200???? Glad I spent the $2000.
It all seems inane to me that we go to the effort to be seen and our reward
is being "filtered out" because some moron thinks we aren't a real threat.


The money you spent on a transponder was well spent. Now you need to
save up and buy a better bull**** filter!


Andy

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?


Tom,

The info included in this ref may be more reliable than some of the
postings here.

http://www.nak.no/flynytt/download/TCAS_II_V7.pdf

I'll check at work to find out what the latest version of the MOPS is.

Andy