Many transponders in close proximity

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outdated or perhaps the testing he did involved procedures that are not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