Many transponders in close proximity

jettester wrote:
\
#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.

A mode S transponder is not required for an aircraft to be detected
by TCAS. The conflicting traffic only needs mode C for the TCAS
to give an RA. The only advantage mode S gives is that if you have
TWO TCAS equipped aircraft, they use the mode S datalink to coordinate
a resolution (one climbs the other descends).

Yuliy Gerchikov wrote:
"jettester" wrote in message
oups.com...
#1. Transponders would not solve the mid air problem unless you were
the only one in close proximity to the attacking aircraft. Typically,

TCAS can't factor multiple threats?!? Even the lowly Zaon MRX can.

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)

TCAS filtering out "highway ground traffic" ...squawking 1200?

I think he's talking about ground radar. TCAS gives not a hoot about
mode A codes.

Yuliy Gerchikov wrote:
"jettester" wrote in message
oups.com...
#1. Transponders would not solve the mid air problem unless you were
the only one in close proximity to the attacking aircraft. Typically,

TCAS can't factor multiple threats?!? Even the lowly Zaon MRX can.

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)

TCAS filtering out "highway ground traffic" ...squawking 1200?

The biggest benefit of transponder is not that people on the ground will see
you -- after all, they are not the ones that are going to hit you. My
transponder is on not as much for the ATC, but for the TCAS/TPAS flying out
there.
--
Yuliy

This is why I love these websites....
The Zaeon MRX Unit is intriguing for several reasons...
1. Its relatively cheap $500
2. It uses 2 self contained batteries (from 5.8 to 7 hrs duration)
3. The ATC radar interogates the other aircraft and the MRX just
listens to the replies
4. You don't have to have a transponder or Mode C
5. Its small and lightweight
6. It gives relative altitude from your altitude (built in digital
altimeter)
7. I don't mess ATC up if I'm not talking or participating with
them.

Draw backs are... it still only helps with finding other aircraft with
transponders and mode C.

I'm glad to hear that at places like Minden and Arizona you guys are
using a discrete code with ATC's blessing. It still would mean you are
talking with the ATC controllers on their freq.
.... Incidentally, we (USAF) did tests with fibreglas gliders to see if
we could "see" them with ATC radars.. you typically could not unless
they increased their power above the rated power they were authorized
at the time... yet, if we put wadded up tin foil (Reynolds Aluminum
wrap) in the wings, they showed up like gang busters.

Jettester (UP)

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)

jettester wrote:

I'm glad to hear that at places like Minden and Arizona you guys are
using a discrete code with ATC's blessing. It still would mean you are
talking with the ATC controllers on their freq.

No talking for code 0440 is required at Minden, anymore than is required
for code 1200. You just punch it in and use it while VFR.

... Incidentally, we (USAF) did tests with fibreglas gliders to see if
we could "see" them with ATC radars.. you typically could not unless
they increased their power above the rated power they were authorized
at the time... yet, if we put wadded up tin foil (Reynolds Aluminum
wrap) in the wings, they showed up like gang busters.

Seattle center and the local approaches don't seem to have problems
seeing our gliders, especially if we announce our prescence. Perhaps
your tests predate the newer radars?

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

Eric Greenwell - Washington State, USA

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

Eric Greenwell wrote:
jettester wrote:

I'm glad to hear that at places like Minden and Arizona you guys are
using a discrete code with ATC's blessing. It still would mean you are
talking with the ATC controllers on their freq.

No talking for code 0440 is required at Minden, anymore than is required
for code 1200. You just punch it in and use it while VFR.

... Incidentally, we (USAF) did tests with fibreglas gliders to see if
we could "see" them with ATC radars.. you typically could not unless
they increased their power above the rated power they were authorized
at the time... yet, if we put wadded up tin foil (Reynolds Aluminum
wrap) in the wings, they showed up like gang busters.

Seattle center and the local approaches don't seem to have problems
seeing our gliders, especially if we announce our prescence. Perhaps
your tests predate the newer radars?

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

Eric Greenwell - Washington State, USA

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

I did a Electronics Counter Measures test in the late 1980's against
their (Seattle's) radar, and their's is the newest in the country and
the most capable.

Jettester (UP)

jettester wrote:
... Incidentally, we (USAF) did tests with fibreglas gliders to see if
we could "see" them with ATC radars.. you typically could not unless
they increased their power above the rated power they were authorized
at the time... yet, if we put wadded up tin foil (Reynolds Aluminum
wrap) in the wings, they showed up like gang busters.


Tucson approach had no problem seeing my ASW-19B, and vectoring airline
traffic round me as a climbed. I was not squawking anything except
"please let me stay here long enough to get enough altitude to get
home".


Andy

jettester wrote:
Eric Greenwell wrote:
jettester wrote:

I'm glad to hear that at places like Minden and Arizona you guys are
using a discrete code with ATC's blessing. It still would mean you are
talking with the ATC controllers on their freq.
No talking for code 0440 is required at Minden, anymore than is required
for code 1200. You just punch it in and use it while VFR.

... Incidentally, we (USAF) did tests with fibreglas gliders to see if
we could "see" them with ATC radars.. you typically could not unless
they increased their power above the rated power they were authorized
at the time... yet, if we put wadded up tin foil (Reynolds Aluminum
wrap) in the wings, they showed up like gang busters.
Seattle center and the local approaches don't seem to have problems
seeing our gliders, especially if we announce our prescence. Perhaps
your tests predate the newer radars?


I did a Electronics Counter Measures test in the late 1980's against
their (Seattle's) radar, and their's is the newest in the country and
the most capable.

I suppose improvements in the last 18 years in their hardware, software,
and power authorizations could mean your tests are no longer useful
references for their abilities nowadays? Anecdotally, it seems like they
are better than you measured back then.

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

Eric Greenwell - Washington State, USA

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

Andy wrote:
Tucson approach had no problem seeing my ASW-19B, and vectoring airline
traffic round me as a climbed. I was not squawking anything except
"please let me stay here long enough to get enough altitude to get
home".

They could see a Kestrel back in the mid 1970's at 30 miles or so if I
recall correctly. One of the Tcson Soaring Club members did some
testing with them.

-Tom

One thing, if you do decide to buy a transponder or other collision
avoidance device, please support the retailers who support soaring.
Don't just look for the cheapest internet price.


5Z wrote:
jettester wrote:
Bottom Line - Transponders are NOT the answer! Try putting one of
these new LED Strobe Lights on the top of your Fin instead.

EXCELLENT response! Sounds like the "transponder" option is to get a
Zaon MRX http://www.zaonflight.com/mrx.html It's better if I'm AWARE
of ALL the transponders nearby instead of just trying to become visible
to a few others with limited success.

Did a quick Google search for LED strobes and these are intriguing, but
looks like 1/3 to 1/2 amp drain, so even worse than transponder. But,
it may be possible to rig these to flash less frequently...

-Tom