New transponder mode S vs. mode C

Marc Ramsey wrote:
Why would you want a Mode S transponder to be fed by a GPS? The
Extended Squitter variation of ADS-B does layer on top of the Mode S
downlink protocol, but simply feeding GPS data to a Mode S transponder
will not make it ADS-B compliant. An entirely new box will be needed.

The only reason to use a Mode S transponder in the US (outside of the
categories of aircraft for which it is mandated) is to take advantage of
the uplinked traffic and weather information, which needs an expensive
and power hungry multi-function display. Since some of those services
are now being shut down in anticipation of ADS-B deployment, even that
reason is slowly being rendered meaningless. Also, do not forget that
it costs roughly twice as much to recertify a Mode S transponder, and
you may have to go farther to find a shop that has the right test equipment.

In response to the original poster, if you spend extra money to install
and maintain a Mode S (instead of C) transponder in a glider operating
in the US, you're simply wasting money...

Marc

Gary Emerson wrote:
AH, but the real question is... would a 302 or other GPS be capable of
generating the data that could be fed to a Mode S transponder? Yeah,
yeah all the illegal stuff and your insurance would never pay if you
ground looped..., but would it work or are the certified GPS units
sending out a different data protocol?

hans wrote:
Hi Tom!

your 302 does not qualify as a certified GPS for the mode S transponder.

Best Regards


Hans


Tom N. schrieb:

I live in San Antonio, Texas, USA. We fly out of a field 15 nautical
miles away from San Antonio International airport and are basically on
final approach for a lot of jet traffic. There are also two Air Force
bases in the immediate area. There is no requirement in the U.S. to
have mode S as there will be in Europe. However, if there is less
power consumption due to fewer interrogations or if there is more
accuracy on TCAS, I would be willing to go with it. I use a Cambridge
302 for GPS.
Stefan wrote:

Tom N. schrieb:

Any opinions? I plan to install a new Becker transponder in my
ASW-28.
Should I go with the old mode C unit or pay extra for the new mode S
unit? Thanks.

Tor answer this question, it would be extremely helpful to know in
which
part of the world you intend to fly.



Hi Marc - I purchased mode S simply because there doesn't seem
to be a material cost difference with the current available equipment.
In Europe and other parts of the world, Mode S is becoming required,
so as I may take my toy and fly in other countries it seems prudent !
I haven't checked if there's any difference in recertification cost
with the local shops.

Hope that helps,
Best Regards, Dave

A couple of points:

Military flights are IFR most of the time - with obvious exceptions
when on a low-level route or in a restricted area. At the altitudes
most gliders fly (except for ridges), T-38s and pretty much everything
else will be on Center freq and in contact with center. And ALL
military aircraft have transponders, and are required to use them, and
most fighters can interrogate other transponders (much better than TCAS
IMHO), and have air-to-air search radars that can see gliders.

The new T-38C has a glass cockpit, HUD, GPS, and probably TCAS (it
would make sense in a training environment), but not sure about the
TCAS. But T-38s are kept on a short leash on very structured training
missions - they aren't just wandering around looking for gliders to
bounce!

The threat from military fast movers is at low altitudes, or near
high-traffic areas. Stay out of hot MOA's during the week, know where
the LLTRs cross your local ridge, don't wander into a restricted area -
and you are safe from the military.

Now, Joe Bagadonuts in his 1959 Cezzna 172, sightseeing VFR ("Lucille,
I thought I told you to clean the mud and bugs off the windshield last
year!") - good luck detecting him! No transponder (or it doesn't
work), not talking to anybody, not looking out the window cuz he's
trying to figure out his newfangled GPS thingy...

Kirk
66

Kirt,

"Stay out of MOAs during the week"? So I guess you can only fly in Nevada,
and large areas of other western states, on week-ends when the MAOs are only
being used by the Air National Guard. I also doubt that the F-18s based at
Fallon, NV, F-15s and F-16s based at Mt Home, ID are flying IFR most of the
time. In fact, I can't think of any place where combat fighter training is
conducted that you will find "F" series aircraft flying mostly IFR.

On a cross country last summer a couple F-16s came quite close to a couple
of local gliders. One of the pilots called Mt Home AFB just to find out if
the F-16s had spotted the gliders. The Mt Home AFB representative stated
that one of the pilots saw a flash of white and after the fact determined
that it must have been a glider. So much for being spotted on their radar.

You are totally correct stating that avoiding low-level routs, restricted
areas and MAOs will nearly eliminate military aircraft conflicts. In fact
all glider accidents can also be avoided by leaving your glider is its'
trailer.

Respectfully,

Wayne
P.S. My comments are biased by my experience flying A-6 Intruders 30 years
ago.
http://www.soaridaho.com/


"kirk.stant" wrote in message
oups.com...
A couple of points:

Military flights are IFR most of the time - with obvious exceptions
when on a low-level route or in a restricted area. At the altitudes
most gliders fly (except for ridges), T-38s and pretty much everything
else will be on Center freq and in contact with center. And ALL
military aircraft have transponders, and are required to use them, and
most fighters can interrogate other transponders (much better than TCAS
IMHO), and have air-to-air search radars that can see gliders.

The new T-38C has a glass cockpit, HUD, GPS, and probably TCAS (it
would make sense in a training environment), but not sure about the
TCAS. But T-38s are kept on a short leash on very structured training
missions - they aren't just wandering around looking for gliders to
bounce!

The threat from military fast movers is at low altitudes, or near
high-traffic areas. Stay out of hot MOA's during the week, know where
the LLTRs cross your local ridge, don't wander into a restricted area -
and you are safe from the military.

Now, Joe Bagadonuts in his 1959 Cezzna 172, sightseeing VFR ("Lucille,
I thought I told you to clean the mud and bugs off the windshield last
year!") - good luck detecting him! No transponder (or it doesn't
work), not talking to anybody, not looking out the window cuz he's
trying to figure out his newfangled GPS thingy...

Kirk
66

Wayne Paul wrote:
Kirt,

"Stay out of MOAs during the week"? So I guess you can only fly in Nevada,
and large areas of other western states, on week-ends when the MAOs are only
being used by the Air National Guard. I also doubt that the F-18s based at
Fallon, NV, F-15s and F-16s based at Mt Home, ID are flying IFR most of the
time. In fact, I can't think of any place where combat fighter training is
conducted that you will find "F" series aircraft flying mostly IFR.

Wayne, I said "stay out of HOT MOAs". If you want to tangle with some
A-10s or F-16s conducting BFM in a MOA, knock yourself out - but don't
be surprised if you get a face full of fighter!

Maybe you Navy guys in A-6s rooted around VFR all the time, but in my
time in the AF (F-4s) we were IFR (but not usually IMC) to and from the
ranges, MOA's, or low level routes. That is still a big part of the
flight. When you finished your low level route, you popped up,
contacted center, and got a clearance and a Mode 3 (transponder) code
for the trip home - under an IFR clearance. Still applies today,
according to my F-16 and F-15 buddies.

On a cross country last summer a couple F-16s came quite close to a couple
of local gliders. One of the pilots called Mt Home AFB just to find out if
the F-16s had spotted the gliders. The Mt Home AFB representative stated
that one of the pilots saw a flash of white and after the fact determined
that it must have been a glider. So much for being spotted on their radar.

That doesn't say much, really. They may have picked up the gliders as
traffic on their radar an maneuvered to avoid, and just not see the
glider. I have seen F-16 HUD video of a radar lock on a G-102 (N123BG,
to be precise), so detection is possible. In that case it was the
wingman who locked on (automatically), and he didn't see the glider
until REAL close as he was watching lead and changing freq.
Fortunately the glider pilot saw the F-16 and actually enjoyed the
close encounter (no it wasn't me!)

You are totally correct stating that avoiding low-level routs, restricted
areas and MAOs will nearly eliminate military aircraft conflicts. In fact
all glider accidents can also be avoided by leaving your glider is its'
trailer.

I just don't think military traffic is much of a factor in the real
world - but common sense should prevail. In my glider flying in AZ,
NV, UT, IL, OH, and VA, I've never felt contrained by airspace or
threatened by military traffic. Or airliners (easy to see!).
Bugsmashers? You bet!

Respectfully,

Wayne
P.S. My comments are biased by my experience flying A-6 Intruders 30 years
ago.

Cool jet!

I talked today to Filser and Becker, and they both confirmed that their
mode-S transponders will support extended quitter with GPS information
transmitted, if a GPS is connected in the near future. It will be a
software update.

Marc Ramsey schrieb:
Why would you want a Mode S transponder to be fed by a GPS? The
Extended Squitter variation of ADS-B does layer on top of the Mode S
downlink protocol, but simply feeding GPS data to a Mode S transponder
will not make it ADS-B compliant. An entirely new box will be needed.

hans wrote:
I talked today to Filser and Becker, and they both confirmed that their
mode-S transponders will support extended quitter with GPS information
transmitted, if a GPS is connected in the near future. It will be a
software update.

They will also have to jump through a lot of certification hoops, at
least here in the US. I'd be quite happy if they can manage to do so
without requiring an expensive RAIM/WAAS certified GPS unit...

Marc

Mode S and ADS-B are completely different technologies.

Mike Schumann

"Eric Greenwell" wrote in message
news:%Lv3h.2739$bg7.2620@trndny04...
Mike Schumann wrote:
You need a graphic display device, like a Garmin 430 to see traffic.
Beware. The FAA has announced that new radars will not support the
Traffic Info function, so the main advantage of Mode S will be gone. I
would opt for a low cost solution, as eventually ADS-B will obsolete both
Mode S and Mode C transponders.

I read somewhere that mode S transponders were going to be the data-link
platform for ADS-B, though it wasn't clear if all mode S transponders
would be capable of it. Has the FAA chosen some other other platform?

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

"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

A Mode S transponder does not need any inputs from a GPS.

Mike Schumann

"Gary Emerson" wrote in message
t...
AH, but the real question is... would a 302 or other GPS be capable of
generating the data that could be fed to a Mode S transponder? Yeah, yeah
all the illegal stuff and your insurance would never pay if you ground
looped..., but would it work or are the certified GPS units sending out
a different data protocol?

hans wrote:
Hi Tom!

your 302 does not qualify as a certified GPS for the mode S transponder.

Best Regards


Hans


Tom N. schrieb:

I live in San Antonio, Texas, USA. We fly out of a field 15 nautical
miles away from San Antonio International airport and are basically on
final approach for a lot of jet traffic. There are also two Air Force
bases in the immediate area. There is no requirement in the U.S. to
have mode S as there will be in Europe. However, if there is less
power consumption due to fewer interrogations or if there is more
accuracy on TCAS, I would be willing to go with it. I use a Cambridge
302 for GPS.
Stefan wrote:

Tom N. schrieb:

Any opinions? I plan to install a new Becker transponder in my
ASW-28.
Should I go with the old mode C unit or pay extra for the new mode S
unit? Thanks.

Tor answer this question, it would be extremely helpful to know in
which
part of the world you intend to fly.

Mike Schumann wrote:
Mode S and ADS-B are completely different technologies.

Potentially some overlap, though. I found this on the AOPA website,
dated July 5, 2006:

Also, in the United States the FAA chose UAT — universal access
transceiver — as the ADS-B datalink for general aviation. Australia
chose to use as its ADS-B datalink the 1090-MHz Mode S extended
squitter system. Mode S extended squitter does not have nearly the
data capacity of UAT, nor is it as robust.

What adds some confusion to this is the airliners will be using mode S
for the ADS-B datalink. From AOPA again:

A second ADS-B datalink is the 1090 Mode S Extended Squitter. The
1090 ADS-B datalink will be used by the airlines (which already have
Mode S systems they can upgrade).

So, it looks like general aviation types like us will be using the UAT
instead of mode S. Given that, buying mode S won't even be useful for a
USA pilot that wants to add ADS-B when it becomes available.

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

"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

Mike!

you are correct that a mode S transponder does not require any input
form a GPS. But in some areas of the world it (will be)/(is) useful to
supply the mode S transponder with current position information so that
the mode S transponder can disseminate this information via extended
squitter.

Hans







Mike Schumann schrieb:
A Mode S transponder does not need any inputs from a GPS.

Mike Schumann

"Gary Emerson" wrote in message
t...
AH, but the real question is... would a 302 or other GPS be capable of
generating the data that could be fed to a Mode S transponder? Yeah, yeah
all the illegal stuff and your insurance would never pay if you ground
looped..., but would it work or are the certified GPS units sending out
a different data protocol?

hans wrote:
Hi Tom!

your 302 does not qualify as a certified GPS for the mode S transponder.

Best Regards


Hans


Tom N. schrieb:

I live in San Antonio, Texas, USA. We fly out of a field 15 nautical
miles away from San Antonio International airport and are basically on
final approach for a lot of jet traffic. There are also two Air Force
bases in the immediate area. There is no requirement in the U.S. to
have mode S as there will be in Europe. However, if there is less
power consumption due to fewer interrogations or if there is more
accuracy on TCAS, I would be willing to go with it. I use a Cambridge
302 for GPS.
Stefan wrote:

Tom N. schrieb:

Any opinions? I plan to install a new Becker transponder in my
ASW-28.
Should I go with the old mode C unit or pay extra for the new mode S
unit? Thanks.
Tor answer this question, it would be extremely helpful to know in
which
part of the world you intend to fly.