Collision Avoidance Systems

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 does not have TCAS; they need to be in
contact with ATC to know that your transponder-equipped glider is
nearby.

My choice was the tiny Zaon MRX. I use the rechargeable batteries
recommended. This model gives relative altitude, altitude trend, and
distance. Its beep beep is cheap cheap.

It does not give azimuth information, but it has forced me to improve
my 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).

Portability is an added advantage of the MRX. When doing introductory
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 and react to transponder-equipped
gliders. But the smaller 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.

Making transponders cheaper for gliders would be possible if the FAA
relaxed some of its technical specifications. Since Santa Claus didn't
show up with money, I can't have both a PCAS and a transponder, yet.

Raul Boerner
DM
LS6-B

jcarlyle wrote:
Last week, before the Minden midair, I reviewed Collision Avoidance

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 (snip)

WTF are military signals X and Y? Military uses IFF modes 1, 2, 3
(same as civilian mode A or 3/A), C (same as civilian mode C - gives
altitude only), 4 (secure), and S. I'm hoping "X" and "Y" are modes 1
and 4, since most military traffic have those on all the time-
especially mode 4.

Neat device, though, and definitely on my xmas list!

Kirk
66

Kirk, will a TPAS which can only receive mode A,C, and S will detect
any military aircraft?

kirk.stant wrote:
jcarlyle wrote:
Last week, before the Minden midair, I reviewed Collision Avoidance

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 (snip)

WTF are military signals X and Y? Military uses IFF modes 1, 2, 3
(same as civilian mode A or 3/A), C (same as civilian mode C - gives
altitude only), 4 (secure), and S. I'm hoping "X" and "Y" are modes 1
and 4, since most military traffic have those on all the time-
especially mode 4.

Neat device, though, and definitely on my xmas list!

Kirk
66

Ramy wrote:
Kirk, will a TPAS which can only receive mode A,C, and S will detect
any military aircraft?


Ramy,

In peacetime all military flights (caveat - my experience is AF, Navy
and Army may be different) are on IFR flightplans, so will be squawking
Mode 3/C (same as mode A/C). During certain phases of flight, they may
cancel and go VFR, but will still be squawking mode 3C/1200, just like
everyone else. Some newer jets may have mode S installed (C-17? F-22?)
in which case that would be on also.

It's possible during training in restricted airspace that mode 3 (and
S) may be turned off (so the other guy can't find you with his onboard
interrogator) but there shouldn't be any civilian traffic in that
airspace.

Other military modes (1, 2, and 4) are used as tactics and conditions
require, but are not required. More than likely they would be on
during routine flight to and from bombing ranges and restricted
airspace, and while using MOAs, so that other military planes equipped
with IFF interrogators can see and identify them.

Short answer - yes!

Hope this helps,

Kirk
66

I bought a Zaon MRX earlier this year and I have been very pleased. It
is a small, passive system that only requires me to turn it on before
flight and turn it off after the flight is over. I bought it at Wings
and Wheels for approx $ 500.00 and I do feel that it a very valuable
safety device that folks should really consider purchasing, especially
for those operating in areas with a fair amount of commercial jet
and/or general aviation traffic. I operate out of Moriarty, NM (30 NM
East of Albuquerque, NM) and we have a fair amount of jet traffic
descending toward the Albuquerque International Sunport or climbing out
on departure. The MRX has really worked very well alerting me to
aircraft that get within 5 NM and 5,000 feet! - 3R

"jcarlyle" wrote in message
ups.com...

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


Even after reading the web site and the manual, I am not clear about the
audio alert provided by this unit. Does it lack a method to hear the alert
through your headset? If so, it would be great for glider use, but perhaps
worse than useless in an airplane because the tiny speaker would be inaudible,
thus the gadget would just give you one more reason to keep your eyes focused
inside the cockpit.

Inquiring minds want to know.


Vaughn (a guy who goes both ways)

Vaughn, Kirk,

The easy one first - no, there is no headset output on the MRX. I
talked with our tow pilot today, and he, too, identified this as a
drawback for power planes. The XRX does have such an output, as does
the ADT-300 and the Proxalert R5.

As for military signals X and Y, the manual is no help. After a bit of
Googling, I'll take a guess, though - I think these refer to Tacan
signals. One of the frequencies Tacan can transmit on is 1090 MHz, like
a transponder. Unknown to me is whether a Tacan signal has altitude
encoded in it, but it appears that the output power of a Tacan unit is
the same as a transponder, so the distance measurement scheme these CAS
units use would work. Again, just a guess - what I don't know about
military flying would fill large books!

I flew today with the MRX, and I can report that in my ASW-19 it works
very well. I was amazed at how much traffic it picked up that I was
unaware of until the traffic got within 2 miles or so. The real
benefit, though, was the MRX alerting me to a helicopter that was at
500 feet, a half mile away, and was vectoring in on the tow plane and I
just after takeoff. To me, the $500 cost of the MRX has already been
repaid! On another note, in my ASW-19 I wouldn't want anything bigger
than the MRX on the glareshield. I know the XRX wouldn't fit, and I
don't think the Proxalert R5 would either (although the ADT-300 would).

-John

Vaughn Simon wrote:
Even after reading the web site and the manual, I am not clear about the
audio alert provided by this unit. Does it lack a method to hear the alert
through your headset? If so, it would be great for glider use, but perhaps
worse than useless in an airplane because the tiny speaker would be inaudible,
thus the gadget would just give you one more reason to keep your eyes focused
inside the cockpit.

kirk.stant wrote:
WTF are military signals X and Y? Military uses IFF modes 1, 2, 3
(same as civilian mode A or 3/A), C (same as civilian mode C - gives
altitude only), 4 (secure), and S. I'm hoping "X" and "Y" are modes 1
and 4, since most military traffic have those on all the time-
especially mode 4.

As for military signals X and Y, the manual is no help. After a bit of
Googling, I'll take a guess, though - I think these refer to Tacan
signals. One of the frequencies Tacan can transmit on is 1090 MHz, like
a transponder. Unknown to me is whether a Tacan signal has altitude
encoded in it, but it appears that the output power of a Tacan unit is
the same as a transponder, so the distance measurement scheme these CAS
units use would work. Again, just a guess - what I don't know about
military flying would fill large books!


I thought of that, but think it's unlikely. TACAN is basically a UHF
"VOR"/DME equivalent, and is also used by civilians - airliners and
bizjets - and civilian DME is the distance measuring part of TACAN.
TACANs have both X and Y channels, Y being used for Air-to-Air distance
and bearing between cooperating aircraft (useless info: must set your
TACAN channels 63 apart to work: CH 29Y and CH 92Y are commonly used).
Anyway, only the DME portion transmits, the bearing portion is receive
only - like VOR. So it's unlikely that TACAN signals are being used,
in my opinion. If they are, then civilian DME should also trigger the
TPAS!

But I could be wrong...

Kirk

Kirk

Kirk,

I called up Zaon, and they said that the X and Y signal modes they
receive are indeed DME.

-John

wrote:
I thought of that, but think it's unlikely. TACAN is basically a UHF
"VOR"/DME equivalent, and is also used by civilians - airliners and
bizjets - and civilian DME is the distance measuring part of TACAN.
TACANs have both X and Y channels, Y being used for Air-to-Air distance
and bearing between cooperating aircraft (useless info: must set your
TACAN channels 63 apart to work: CH 29Y and CH 92Y are commonly used).
Anyway, only the DME portion transmits, the bearing portion is receive
only - like VOR. So it's unlikely that TACAN signals are being used,
in my opinion. If they are, then civilian DME should also trigger the
TPAS!

jcarlyle wrote:
Kirk,

I called up Zaon, and they said that the X and Y signal modes they
receive are indeed DME.


Interesting.

Then it should also see civilian DME. Too bad GPS is pretty much
replacing DME in military and civilian aircraft.

Thanks for the info - learned something new!

Kirk
66