Nice summary of the PCAS models available. Airliners and some corporate

jets have TCAS; they can "see" you without having to be told by ATC.
Smaller motorized traffic likely do not have TCAS; they need to be in
contact with ATC to know that your transponder-equipped glider is
nearby.

My choice was the Zaon MRX. Small, small, small. I run it on the
rechargeable batteries recommend by Zaon (multiple flights per set of
batteries). This model gives relative altitude, altitude trend, and
distance. And its beep beep is cheap cheap.

It does not give azmuth information, but it has forced me to improve on

the good old-fashioned rubber-necking see-and-avoid procedure. One of
the advantages of the MRX is that the alerts are audible; we already
have too much heads-down technology in gliders to install more
equipment that requires visual monitoring.

When my MRX gives two beeps, I start looking everywhere (mine is set to

beep twice for traffic within 1NM and 1,000 feet). When it advances to
four beeps, I start looking everywhere with super motivation (mine is
set to beep four times when traffic is less than 1NM horizontal and 700

feet vertical).

Portablility is an added advantage of the MRX. When doing intoductory
rides for our club, I take my MRX unit with me.

The advantage of PCAS over the transponder is that you, the glider
pilot, is alerted to all traffic with transponders. This includes
Cessna 152s, corporate jets, commuters and large airliners. If all I
had was a transponder, I would have to be in communication with ATC and

under radar coverage to be available to be told about other traffic.

Airliners with TCAS are able to see transponder-equipped gliders and
react. But, small powered aircraft cannot electronically see those same

gliders unless those small powered aircraft are communicating with ATC
(in a radar environment).

PCAS (portable collision avoidance system) gives me more peace of mind.

Given the choice between only some of them being able to see me, or me
being able to see most of them, is the main reason I chose the MRX over

a transponder.

Last week, I had a couple of "two beep" alerts. Both of these aircraft
came up from behind and below. But I was able to spot them sooner than
when I did not have the MRX.

But when Santa Claus comes with money, I'll have both a PCAS and a
transponder.






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).