Many transponders in close proximity

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)