Transponder Praise

On Jul 5, 11:27*pm, Soarin Again wrote:
At 16:34 05 July 2008, jcarlyle wrote:

My Zaon MRX alerted us to traffic at our altitude 5 miles
away, which then rapidly closed on us. Despite our best
efforts over the next 30 seconds, neither my friend nor
I saw anything approaching.
Then suddenly we saw a business jet in a 45-50 degree
bank less than a mile away. Apparently my transponder
caused a TA on his TCAS, he looked outside and saw our
wings flashing, and he turned away from the impending collision.

Assuming that you are talking nautical miles. *If you are alerted
to the aircraft at 5 miles and within 30 seconds he is at 1 mile
then is apparently doing 480 knots (well above the 250 kt limit
below 10,000 msl).
If you don't see him and you know he is at your altitude and
closing at that high of a rate, why not just pull full spoilers and
dive to vacate that altitude as quickly as possible?
Is there a better option available?

The distance measurements with PCAS are approximate and only based on
radiated power from the other aircraft's transponder and can be fooled
as the aircraft change atitudes/altirudes relateive to each other.

With two gliders flying near each other and both thermalling (so that
you are most visible to other traffic) I'd be trying to stay with the
other glider (traffic might see and try to avoid one glider and hit
the other), I'd be focused on scanning for the traffic and not be
shoving the nose over and pulling spoilers unless I could see the
traffic and thought that was a good thign to do. If traffic is
getting close on PCAS and I can't see it I will bank or turn the
glider to have a good look around.


Darryl

Six or seven years ago, I started to fly out of Jean, Nevada fairly
often so I installed a transponder. Jean is just outside the Las Vegas
Class B (8 to 9,000' at 20NM), and under the Mode C Veil which - not
printed on charts - is essentially Class B between 9 and 10,000'
unless you have a transponder or use a negotiated climb window.
One weekday morning, the pilot for the skydiving operation helped me
rig. That evening he helped me put the glider back in the box.
As we were pulling tape, he said: "You have a transponder, don't you?
I heard ATC vectoring aircraft around you." The pilot must actually
talk with control before a jump run to allow several small objects to
drop through the veil.
That confirmed the good idea of installing the transponder and
batteries.
Just installed and certified a transponder in the new flying
machine, too. But this is old technology. When we all have
transponders it will drive ATC crazy with gaggles of proximity alarms
going off. Be better if every aircraft had FLARM.
Jim

JS wrote:

Just installed and certified a transponder in the new flying
machine, too. But this is old technology. When we all have
transponders it will drive ATC crazy with gaggles of proximity alarms
going off.

That can be handled with an assigned code like the 0440 used in Reno for
gliders. The software can be instructed to ignore conflicts between 0440
codes, which, I believe, is what is done in Reno. There may be other
methods they can already use, especially if the glider density is lower
than Reno.

Be better if every aircraft had FLARM.

We will, in 10 to 20 years, but we'll likely call it ADSB. FLARM, as
presently implemented, probably wouldn't appeal to 250+ knot airliners,
because it's range is too small. I think it's better to work for a low
cost, low power, ADSB with modest features like the Mitre unit.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

the system will not give alarms for multiple 1200 codes in the same vicinity
that might conflict with each other
it will give an alarm for a discreet code conflicting with another discrete
code.. (0440 is not considered discrete)
It may or may not give alarms if a discrete code will conflict with a 1200
code

The jumpers at Jean have negotiated 1201, 1202, 1203 etc so TRACON instantly
knows it's the jump plane.

BT

"Eric Greenwell" wrote in message
news:Bj9ck.310$rb1.279@trndny08...
JS wrote:

Just installed and certified a transponder in the new flying
machine, too. But this is old technology. When we all have
transponders it will drive ATC crazy with gaggles of proximity alarms
going off.

That can be handled with an assigned code like the 0440 used in Reno for
gliders. The software can be instructed to ignore conflicts between 0440
codes, which, I believe, is what is done in Reno. There may be other
methods they can already use, especially if the glider density is lower
than Reno.

Be better if every aircraft had FLARM.

We will, in 10 to 20 years, but we'll likely call it ADSB. FLARM, as
presently implemented, probably wouldn't appeal to 250+ knot airliners,
because it's range is too small. I think it's better to work for a low
cost, low power, ADSB with modest features like the Mitre unit.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

We may not have to wait 10-20 years. The new MITRE low cost ADS-B
transceiver (transmitting your location, while also receiving traffic &
weather data) should be in testing this fall. The last I heard, they
already have a couple of companies lined up to license the design for
commercial production.

Mike Schumann

"Eric Greenwell" wrote in message
news:Bj9ck.310$rb1.279@trndny08...
JS wrote:

Just installed and certified a transponder in the new flying
machine, too. But this is old technology. When we all have
transponders it will drive ATC crazy with gaggles of proximity alarms
going off.

That can be handled with an assigned code like the 0440 used in Reno for
gliders. The software can be instructed to ignore conflicts between 0440
codes, which, I believe, is what is done in Reno. There may be other
methods they can already use, especially if the glider density is lower
than Reno.

Be better if every aircraft had FLARM.

We will, in 10 to 20 years, but we'll likely call it ADSB. FLARM, as
presently implemented, probably wouldn't appeal to 250+ knot airliners,
because it's range is too small. I think it's better to work for a low
cost, low power, ADSB with modest features like the Mitre unit.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org


** Posted from http://www.teranews.com **

What is the group’s suggestion on the best procedure to follow when
flying a transponder equipped sailplane outside of an area where
specific squawk codes have been assigned, ie, where you get lumped in
with other VFR traffic? It’d be nice if gliders and balloons had a
discrete squawk code everywhere in the US, so ATC would know
immediately that we were a different kind of traffic, but since that’s
not going to happen soon (if ever) what strategies could glider pilots
use to stay as safe as possible?

Currently I’m squawking 1200, communicating on 123.3 with other XC
gliders, monitoring my Zaon MRX PCAS for transponder equipped traffic,
and of course constantly visually scanning for traffic. As Darryl
said, if my PCAS alerts me to closing traffic and I don’t see it, I
start turning while increasing my visual scan. This makes me more
visible to them, and allows me to look at what was my 6 o’clock. I
also tend to get more vigilant when I’m nearing a VOR as well as when
I'm flying at a multiple of 1000 feet, as I figure other traffic tends
to fly at those locations and altitudes.

One hardware change I plan on making soon is to move my PCAS antenna
from the instrument panel area to a location back in the tail boom. My
PCAS antenna is now getting shadowed from multiple directions by
various instruments from the rear and below, by the compass from the
front and above, by the canopy and instrument panel lifting mechanism
from the front, and by the rudder pedal assembly from the front and
below. In the tail boom the only real shadowing will come from the
landing gear from the front. Shadowing of the PCAS antenna in its
present location might explain why the business jet closed with my
friend and I so quickly.

-John

On Jul 6, 3:36 am, Darryl Ramm wrote:
The distance measurements with PCAS are approximate and only based on
radiated power from the other aircraft's transponder and can be fooled
as the aircraft change atitudes/altirudes relateive to each other.

With two gliders flying near each other and both thermalling (so that
you are most visible to other traffic) I'd be trying to stay with the
other glider (traffic might see and try to avoid one glider and hit
the other), I'd be focused on scanning for the traffic and not be
shoving the nose over and pulling spoilers unless I could see the
traffic and thought that was a good thign to do. If traffic is
getting close on PCAS and I can't see it I will bank or turn the
glider to have a good look around.

Darryl

jcarlyle wrote:

One hardware change I plan on making soon is to move my PCAS antenna
from the instrument panel area to a location back in the tail boom. My
PCAS antenna is now getting shadowed from multiple directions by
various instruments from the rear and below, by the compass from the
front and above, by the canopy and instrument panel lifting mechanism
from the front, and by the rudder pedal assembly from the front and
below. In the tail boom the only real shadowing will come from the
landing gear from the front. Shadowing of the PCAS antenna in its
present location might explain why the business jet closed with my
friend and I so quickly.

Shadowing is certainly a possibility. I've also wondered if the amount
of radar interrogations can cause the same thing; e.g., where I fly in
SE Washington state, my transponder is triggered only 5-10 times a minute.

Rather than just relocating the antenna, you can get Zaon's dual antenna
option. That puts antennas top and bottom on the aircraft, essentially
eliminating all shadowing. It might be easier than moving one antenna to
the tail, but it's pricey at $280 for the option, plus two blade antennas.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Eric, I wasn't too impressed with the antenna extenders that Zaon
offers. They use RG-174 cable, and while it's OK for short runs it
would markedly decrease the signal strength running from my tail cone
to my instrument panel. I've found several places on line that offer 6
meter male to female RP SMA cables made from LMR 200 for less than
$15. The attenuation with LMR 200 at 1 GHz is 10 dB per 100 feet,
rather than the 22 dB per 100 feet with RG-174.

I guess there's a possibility that high interrogation rates could mess
up the Zaon range estimate, but even here in the PHL NY area the
transponder's transmitting triangle only flashes about once a second.
Could be that there are many, many transmissions per flash, but I've
noticed that generally if the Zaon says the range is within 3 miles of
me it is pretty accurate (to my "calibrated" eye, that is).

-John

On Jul 7, 2:39 pm, Eric Greenwell wrote:
Shadowing is certainly a possibility. I've also wondered if the amount
of radar interrogations can cause the same thing; e.g., where I fly in
SE Washington state, my transponder is triggered only 5-10 times a minute.

Rather than just relocating the antenna, you can get Zaon's dual antenna
option. That puts antennas top and bottom on the aircraft, essentially
eliminating all shadowing. It might be easier than moving one antenna to
the tail, but it's pricey at $280 for the option, plus two blade antennas.

--
Eric Greenwell - Washington State, USA

jcarlyle wrote:
Eric, I wasn't too impressed with the antenna extenders that Zaon
offers. They use RG-174 cable, and while it's OK for short runs it
would markedly decrease the signal strength running from my tail cone
to my instrument panel. I've found several places on line that offer 6
meter male to female RP SMA cables made from LMR 200 for less than
$15. The attenuation with LMR 200 at 1 GHz is 10 dB per 100 feet,
rather than the 22 dB per 100 feet with RG-174.

The PCAS MRX Dual Antenna Harness isn't really an "extender", but a way
of improving coverage to eliminate blind spots. I believe the antennas
used with the extender could be mounted close to the cockpit: e.g., one
on top of the glare shield, and one below it on the outside of the
glider (you couldn't do that on a glider that uses a CG hook to tow
with, of course).

Those locations would allow very short cables, if you wanted to;
however, the fact that two antennas are used probably makes up for
losses in the cable. If my math is right, the 15 foot cables they supply
do cut the signal from each antenna by one half, so that suggests they
intend the total signal (both antennas) to be the same as the one
antenna mounted directly on the unit. In any case, the dual antenna
package and the PCAS MRX Single Antenna Harness include "gain adapters",
so perhaps concerns about signal loss are irrelevant.

I suggest calling tech support at Zaon about the cable to use for a
remote mounting. Proper operation might require these losses, which
could be accounted for by the gain adapter.


I guess there's a possibility that high interrogation rates could mess
up the Zaon range estimate, but even here in the PHL NY area the
transponder's transmitting triangle only flashes about once a second.
Could be that there are many, many transmissions per flash, but I've
noticed that generally if the Zaon says the range is within 3 miles of
me it is pretty accurate (to my "calibrated" eye, that is).

Actually, I was thinking infrequent interrogations might be the problem,
but it was just a guess.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

One option would be to take along a handheld and use it request flight
following from your local center.

Mike Schuman

"jcarlyle" wrote in message
...
What is the group’s suggestion on the best procedure to follow when
flying a transponder equipped sailplane outside of an area where
specific squawk codes have been assigned, ie, where you get lumped in
with other VFR traffic? It’d be nice if gliders and balloons had a
discrete squawk code everywhere in the US, so ATC would know
immediately that we were a different kind of traffic, but since that’s
not going to happen soon (if ever) what strategies could glider pilots
use to stay as safe as possible?

Currently I’m squawking 1200, communicating on 123.3 with other XC
gliders, monitoring my Zaon MRX PCAS for transponder equipped traffic,
and of course constantly visually scanning for traffic. As Darryl
said, if my PCAS alerts me to closing traffic and I don’t see it, I
start turning while increasing my visual scan. This makes me more
visible to them, and allows me to look at what was my 6 o’clock. I
also tend to get more vigilant when I’m nearing a VOR as well as when
I'm flying at a multiple of 1000 feet, as I figure other traffic tends
to fly at those locations and altitudes.

One hardware change I plan on making soon is to move my PCAS antenna
from the instrument panel area to a location back in the tail boom. My
PCAS antenna is now getting shadowed from multiple directions by
various instruments from the rear and below, by the compass from the
front and above, by the canopy and instrument panel lifting mechanism
from the front, and by the rudder pedal assembly from the front and
below. In the tail boom the only real shadowing will come from the
landing gear from the front. Shadowing of the PCAS antenna in its
present location might explain why the business jet closed with my
friend and I so quickly.

-John

On Jul 6, 3:36 am, Darryl Ramm wrote:
The distance measurements with PCAS are approximate and only based on
radiated power from the other aircraft's transponder and can be fooled
as the aircraft change atitudes/altirudes relateive to each other.

With two gliders flying near each other and both thermalling (so that
you are most visible to other traffic) I'd be trying to stay with the
other glider (traffic might see and try to avoid one glider and hit
the other), I'd be focused on scanning for the traffic and not be
shoving the nose over and pulling spoilers unless I could see the
traffic and thought that was a good thign to do. If traffic is
getting close on PCAS and I can't see it I will bank or turn the
glider to have a good look around.

Darryl


** Posted from http://www.teranews.com **