Many transponders in close proximity

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:

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


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.

So, the aircraft climbing or descending at a high rate are the ones
they do NOT want to know about? This had better be wrong.

I suspect jettester's info may also be a little out of date. When did
he say he hung up his spurs?


Jack

588 wrote:
Kilo Charlie wrote:

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


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.

So, the aircraft climbing or descending at a high rate are the ones
they do NOT want to know about? This had better be wrong.

I suspect jettester's info may also be a little out of date. When did
he say he hung up his spurs?


Jack

Sorry to all: I've been gone away from my computer for the holiday!
(was soaring !)

Wow, I was trying to clear up a number of misconceptions that people
typically have concerning Transponders. Did not mean to stir up a
hornets nest. Billy Hill is telling the truth also... so don't
misconstrue my remarks.

It depends on the radar you have in your area. whether you have 'line
of sight' with the glider and transponder whether the controller can
"see" your transponder. This is a continuation of my previous comments.

#7. My comments are reflective of "current" equipment used by ATC and
probably more current transponders than any of you can afford. Not
much has changed in the last 18yrs. Yet, I confirmed my previous
statements with the ATC supervisor here in Wichita as being correct.

#8. If two or more of you are operating on the same squawk code, and
end up with converging tracks or converging altitudes (if Mode C
equipped), you WILL set off ATC's traffic warnings (unless they turn
them off for all other traffic in your/their vicinity).

#9. Transponders are a good thing to have if ATC can "see" you, and
their participating traffic has TCAS.. it will "point" you out to that
traffic. TCAS uses the ATC radar to relay your transponder code and
altitude (if Mode C equipped) to that traffic.

#10. I spoke truthfully about their (ATC) not seeing you if climbing
too rapidly (or descending). It may X'out your info on their scope as
well as your altitude.

#11. A transponder may have helped the Hawker to receive a TCAS warning
if ATC could "see" the glider transponder (line of sight), Mode C would
have reported its altitude, and MTI did not filter because the glider
was not circling. I confirmed that MTI is set 65K in this area.

Jettester (UP)

jettester wrote:

#11. A transponder may have helped the Hawker to receive a TCAS warning
if ATC could "see" the glider transponder (line of sight), Mode C would
have reported its altitude, and MTI did not filter because the glider
was not circling. I confirmed that MTI is set 65K in this area.

Jettester (UP)


TCAS does not depend on the target aircraft responding to ATC radar.
TCAS itself performs the interogation and processes the response
independent of ground radar. Since ground radar is not required, the
MTI settings of a proximate ground radar have no influence of the
visibility of the target to a TCAS equipped aircraft.

TPAS however, does rely on the target responding to someone else.

I'll provide one reference that supports my contention. Can you
provide any that support yours?

to quote from http://www.nak.no/flynytt/download/TCAS_II_V7.pdf

Target Surveillance:

TCAS, independent of any ground inputs,
performs surveillance of nearby aircraft to
provide information on the position and
altitude of these aircraft so the collision
avoidance algorithms can perform their
function.

jettester wrote:

#8. If two or more of you are operating on the same squawk code, and
end up with converging tracks or converging altitudes (if Mode C
equipped), you WILL set off ATC's traffic warnings (unless they turn
them off for all other traffic in your/their vicinity).

This must be a common occurrence at Minden. Perhaps someone can tell us
if this situation is one reason to have separate code for gliders, since
they could turn off the collision warning for 0440?

#9. Transponders are a good thing to have if ATC can "see" you, and
their participating traffic has TCAS.. it will "point" you out to that
traffic. TCAS uses the ATC radar to relay your transponder code and
altitude (if Mode C equipped) to that traffic.

I didn't understand this at all: why would TCAS send an aircraft's code
to ATC, when ATC can already get it when they interrogate the aircraft's
transponder?

#10. I spoke truthfully about their (ATC) not seeing you if climbing
too rapidly (or descending). It may X'out your info on their scope as
well as your altitude.

If the limit is set at 1500 fpm, that won't be a problem very often,
even at Minden. And TCAS will still see you, right?

--
Note: email address new as of 9/4/2006
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

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

Jettester, #9 and #11 are not correct. TCAS does not need ATC radar to
"see" another transponder-equipped aircraft. I believe you may be thinking
of TPAS. Are you familiar with that technology?

Also, my understanding of the process differs from that to which you refer
in #8, in that donflict warnings will not be triggered unless one of the
aircraft is squawking a discrete code assigned by ATC. If the situation you
describe was true, alarms would be constantly triggered due to
VFR-squawkers, which in many areas would render the display confusing at
best, and needlessly distract a controller busy separating IFR traffic.

O

"jettester" wrote in message
ups.com...

588 wrote:
Kilo Charlie wrote:

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


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.

So, the aircraft climbing or descending at a high rate are the ones
they do NOT want to know about? This had better be wrong.

I suspect jettester's info may also be a little out of date. When did
he say he hung up his spurs?


Jack

Sorry to all: I've been gone away from my computer for the holiday!
(was soaring !)

Wow, I was trying to clear up a number of misconceptions that people
typically have concerning Transponders. Did not mean to stir up a
hornets nest. Billy Hill is telling the truth also... so don't
misconstrue my remarks.

It depends on the radar you have in your area. whether you have 'line
of sight' with the glider and transponder whether the controller can
"see" your transponder. This is a continuation of my previous comments.

#7. My comments are reflective of "current" equipment used by ATC and
probably more current transponders than any of you can afford. Not
much has changed in the last 18yrs. Yet, I confirmed my previous
statements with the ATC supervisor here in Wichita as being correct.

#8. If two or more of you are operating on the same squawk code, and
end up with converging tracks or converging altitudes (if Mode C
equipped), you WILL set off ATC's traffic warnings (unless they turn
them off for all other traffic in your/their vicinity).

#9. Transponders are a good thing to have if ATC can "see" you, and
their participating traffic has TCAS.. it will "point" you out to that
traffic. TCAS uses the ATC radar to relay your transponder code and
altitude (if Mode C equipped) to that traffic.

#10. I spoke truthfully about their (ATC) not seeing you if climbing
too rapidly (or descending). It may X'out your info on their scope as
well as your altitude.

#11. A transponder may have helped the Hawker to receive a TCAS warning
if ATC could "see" the glider transponder (line of sight), Mode C would
have reported its altitude, and MTI did not filter because the glider
was not circling. I confirmed that MTI is set 65K in this area.

Jettester (UP)

Kilo Charlie wrote:
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......

I saw jettester's posting, and I think he is wrong, based on my
information from other pilots and ATC people over the last few years.
For example, I don't think ATC has any problem distinguishing a
transponder from ground returns, regardless of the transponder's speed,
so the "MTI" comment doesn't apply. Perhaps jettester's experience is
outdated or perhaps the testing he did involved procedures that are not
normally used by ATC - I don't know.

Also, TCAS is designed to handle multiple targets, and ATC can determine
the location of transponders even if they close to each other. ATC may
not be able to get a reliable altitudes or code readings in that case,
but they know where the group is, and they are not going to let an
aircraft in contact with them fly into a swarm of aircraft.

Here is what Billy Hill posted (in part) on Aug 31 (pilots should also
read his article in the July 2006 Soaring magazine):

"Each controller is required by virtue of the ATC handbook, (7110.65 and
the management handbook 7110.3), to display ALL transponder equipped
aircraft. What the controller does have the option to do is adjust the
filter limits at his scope to exclude the encoded altitude of aircraft
which are not in his assigned airspace.
Had the transponder been turned on by the pilot involved in the
mid-air, the jet would have seen the glider on it's TCAS, and ATC
would have been issuing the glider as traffic to the jet. In the Reno
area, most glider pilots are squawking an non discrete code which
indicates to ATC that they are a glider."

People that have experimented with strobe lights have been disappointed,
because they don't help much in sunny conditions. I don't know if LED
strobes are more visible than the glass bulb type, but they do use less
current.

Enjoy your Becker - it's a far better solution than indicated by jettester.

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

Eric Greenwell - Washington State, USA

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

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