John,
Thankyou for a really useful contribution.
Putting an alerting system in my glider gives ME useful
information that I can act on. Installing a transponder
alone gives me no such information, although it MIGHT
give second-hand info via FAA alerts to other traffic,
or MIGHT alert other traffic to my presence if they
have and use a CAS. And $500 is reasonably affordable,
whereas the total cost of an installed and legalized
transponder is much less so.

Part of the present confusion is the proliferation
of different technical partial solutions to the problem
- transponders [mode C or S], TCAS, ADS-B, FLARM etc
etc etc. Without standardization on one system, none
can reach their potential. Without wishing to decry
any of these systems, each one adds complexity and
to some extent increases heads-down cockpit workload
[even if only to note your battery drainage from time
to time]. Heads-out situation awareness is a desirable
state to aim for and should take preference over the
other interests of techies.

Who would like to use existing technology to come
up with one fit-and-forget unit that would act as a
flight recorder, GPS-enabled ELT, mainly-passive alert
and transmit-on-alert-only transponder ?

But at the end of the day, even with very good
warning of an impending collision, the limited maneuverability
of both a glider and a high-speed aircraft means that
you need to put an eyeball on the threat to have a
hope of avoiding it. We drive highways every day in
reasonable safety - but just think about doing that
with your eyes closed and your trusted passenger telling
you where the other traffic is.

Ian





At 13:30 30 August 2006, Jcarlyle wrote:
Last week, before the Minden midair, I reviewed Collision
Avoidance
Systems with the intent of putting one in my transponder-less
ASW-19. I
was interested in such a system because my glider club
lies inside the
Mode C veil of PHL, because an active military air
base is 5 miles
away, and because there are several airways that lie
within several
miles of us. Here's the result of my research; I hope
it might be of
help to others.

Zaon MRX - This was the one I bought. Pros - shows
threat distance
and height; receives civilian signals A, C, S and 3/A,
as well as
military signals X, Y and 2; alerts are visual and
aural (high pitched
beeps); uses internal power (but can use aircraft power);
is the
smallest system available; can be panel mounted with
remote antenna.
Cons - does not show threat direction; doesn't output
threats via
RS232 to PocketPC type devices. List price $499

Zaon XRX - This is the one I really liked. Pros - shows
threat
direction as well as distance and height; receives
civilian signals A,
C, S and 3/A, and also military signals X, Y and 2;
alerts are visual
and aural (synthesized voice); outputs threats via
RS232 to PocketPC
type devices. Cons - needs aircraft power; fairly large
and tall, and
must be mounted on the glare shield. Supposedly Zaon
will offer a panel
mount version with remote antenna in the future. List
price $1795

Proxalert R5 - I rejected this one. Pros - shows threat
distance
and height; shows squawk code of three threats (but
threats combined if
same squawk); alerts are visual and aural (high pitched
beeps); outputs
threats via RS232 to PocketPC type devices; can be
panel mounted with
remote antenna. Cons - Combines threats with same squawk
code on same
line showing closest threat distance, and flip-flops
threat altitude;
needs aircraft power; only receives civilian A, C and
S signals; fairly
large and hangs over glare shield lip. I also was turned
off by the web
site, when I see poor English in sales literature I
can't help but
wonder if the engineering was also done carelessly.
List price $795

Monroy ADT-300 - I rejected this one. Pros - shows
threat distance
and height (but only if you have an altitude encoding
transponder);
alerts are visual and aural (synthesized voice); second
smallest
available; can be panel mounted with remote antenna.
Cons - Needs
altitude encoding transponder to show threat height;
needs aircraft
power; only receives civilian A, C and S signals; doesn't
output
threats via RS232 to PocketPC type devices. List price
$795

Please note that this list is biased towards my own
needs, in a quiet
glider with no transponder, operating with civilian
and military
aircraft. You might have different requirements, so
do check out the
manufacturer's sites for fuller specs and manuals:
http://www.zaonflight.com/
http://www.monroyaero.com/
http://www.proxalert.com/
A good single reference page to many Collision Avoidance
Systems is
he http://www.avionix.com/collis.html
There are also some (fairly old) threads on RAS on
this subject; you
might wish to search for them.

Be careful up there!

-John
(I have absolutely no connection or financial interest
with any of the
companies named in this message).