TIS (traffic information service)

[[email protected]]

We have had TIS in three of the planes in our partnership for a while
now. I consider it a safety of flight issue. When it is working the
number of unseen planes around you it displays is amazing. I really
don't want to fly without it at this point. Unfortunately is seems
that the data is not being sent more then 25% of the time, if that, in
the Seattle area. I'm aware of the issues of reception, and it's not
an equipment issue with three identical systems (GNS 430/GTX330) having
the same problems. I have spoken with the Center manager and he says
that if the radar is working, mode S and TIS data are working. I am
beginning to think that this is not true. Are you seeing the same
poor TIS data broadcast in your area? Does anyone have additional
information on the issue? I have spoken to AOPA and they are looking
into it. I've spoken with the avionics shop and they hear similar
complaints from other pilots. I've spoken with Garmin and they say
sales of the GTX 330 have fallen to nothing compared with what they had
been. There is no plan to replace our ASR 9 for a decade or so. We
should be able to count on TIS information being available in the
Seattle area for a long time to come. I'd like to see it working
reliably...

Thanks for the help,
Dave

[john smith]

In article . com>,
wrote:

> We have had TIS in three of the planes in our partnership for a while
> now. I consider it a safety of flight issue. When it is working the
> number of unseen planes around you it displays is amazing. I really
> don't want to fly without it at this point. Unfortunately is seems
> that the data is not being sent more then 25% of the time, if that, in
> the Seattle area. I'm aware of the issues of reception, and it's not
> an equipment issue with three identical systems (GNS 430/GTX330) having
> the same problems. I have spoken with the Center manager and he says
> that if the radar is working, mode S and TIS data are working. I am
> beginning to think that this is not true. Are you seeing the same
> poor TIS data broadcast in your area? Does anyone have additional
> information on the issue? I have spoken to AOPA and they are looking
> into it. I've spoken with the avionics shop and they hear similar
> complaints from other pilots. I've spoken with Garmin and they say
> sales of the GTX 330 have fallen to nothing compared with what they had
> been. There is no plan to replace our ASR 9 for a decade or so. We
> should be able to count on TIS information being available in the
> Seattle area for a long time to come. I'd like to see it working
> reliably...

With the current high fuel prices, less people are flying, hence you are
seeing less traffic. :-))

[Larry Dighera]

On 28 Aug 2006 07:31:54 -0700, wrote in
. com>:

>We have had TIS in three of the planes in our partnership for a while
>now. I consider it a safety of flight issue. When it is working the
>number of unseen planes around you it displays is amazing.

I didn't realize this was service was provided by the FAA:

http://www.tc.faa.gov/act310/projects/modes/tis.htm


AIM 4-4-16. Traffic Information Service (TIS)

a. TIS provides proximity warning only, to assist the pilot in the
visual acquisition of intruder aircraft. No recommended avoidance
maneuvers are provided nor authorized as a direct result of a TIS
intruder display or TIS alert. It is intended for use by aircraft
in which TCAS is not required.

b. TIS does not alter or diminish the pilot's basic authority and
responsibility to ensure safe flight. Since TIS does not respond
to aircraft which are not transponder equipped, aircraft with a
transponder failure, or aircraft out of radar coverage, TIS alone
does not ensure safe separation in every case.

c. At this time, no air traffic service nor handling is predicated
on the availability of TIS equipment in the aircraft.


http://www.aopa.org/members/files/pilot/2001/multifunction0108.html
A traffic information service (TIS) feature is also available.
This uses Bendix/King's $5,000 KT 73 datalink transponder to hook
up with air traffic control radar to depict nearby air traffic on
the KMD 550 or 850. TIS shows position, altitude, altitude trend,
and course information on up to eight target airplanes within a
chunk of airspace seven miles horizontally and 3,500 feet
vertically of the TIS-equipped airplane. TIS is currently
available from 80 FAA sites throughout the United States.

http://www.forecastinternational.com/archive/rs/rs12814.htm

It looks like these folks are in charge of TIS:
http://www.tc.faa.gov/act310/Welcome.html

You can contact them here:
http://www.tc.faa.gov/act310/staff/staff2.htm

To find out more information about the Mode S Surveillance
Program, contact:

Communication/Navigation/Surveillance
Engineering and Test Division
Surveillance Branch

Federal Aviation Administration
William J. Hughes Technical Center
Atlantic City International Airport, NJ 08405
Phone: (609) 485-5392
Fax : (609) 485-5995

[Robert M. Gary]

I assume you are saying that your TIS goes into "coast mode" and stops
updating for a period of time. I've found the same to be the case in
the Sacramento area. Also, there are certainly holes in where coverage
is available. If I fly from Sacramento to the Bay Area I'll lose TIS
around Franklin Field and pick it up again near Concord. In general I
think my PCAS system is more reliable but it doesn't give direction.

-Robert


wrote:
> We have had TIS in three of the planes in our partnership for a while
> now. I consider it a safety of flight issue. When it is working the
> number of unseen planes around you it displays is amazing. I really
> don't want to fly without it at this point. Unfortunately is seems
> that the data is not being sent more then 25% of the time, if that, in
> the Seattle area. I'm aware of the issues of reception, and it's not
> an equipment issue with three identical systems (GNS 430/GTX330) having
> the same problems. I have spoken with the Center manager and he says
> that if the radar is working, mode S and TIS data are working. I am
> beginning to think that this is not true. Are you seeing the same
> poor TIS data broadcast in your area? Does anyone have additional
> information on the issue? I have spoken to AOPA and they are looking
> into it. I've spoken with the avionics shop and they hear similar
> complaints from other pilots. I've spoken with Garmin and they say
> sales of the GTX 330 have fallen to nothing compared with what they had
> been. There is no plan to replace our ASR 9 for a decade or so. We
> should be able to count on TIS information being available in the
> Seattle area for a long time to come. I'd like to see it working
> reliably...
>
> Thanks for the help,
> Dave

[Montblack[_1_]]

("john smith" wrote)
> With the current high fuel prices, less people are flying, hence you are
> seeing less traffic. :-))


Hey, that's not funny!

We bought into our gateless community in 1998. We are less than two miles
from the end of 9/27. Small planes used to fly over the house all-the-time
.....it was WONDERFUL!

These days, we regularly have beautiful weekends, and --- nothing! We've
been "watching" this trend for a few years.


Montblack

[John Galban]

wrote:
> I've spoken with Garmin and they say
> sales of the GTX 330 have fallen to nothing compared with what they had
> been. There is no plan to replace our ASR 9 for a decade or so. We
> should be able to count on TIS information being available in the
> Seattle area for a long time to come. I'd like to see it working
> reliably...
>

The reason that GTX330 sales are in the dumper is that the FAA
announced (last year) that they would not implement TIS in future radar
upgrades, as a cost saving measure. This indicates to a lot of buyers
that the FAA is not interesting in supporting the technology long term.

I can't say I'm surprised. I've flown some TIS equipped aircraft
and I think it's one of the best traffic avoidance technologies I've
seen since TCAS. It figures that the FAA would choose to implement
"cost savings" by deleting something that actually works and works
well.

John Galban=====>N4BQ (PA28-180)

[Robert M. Gary]

John Galban wrote:
> wrote:

> The reason that GTX330 sales are in the dumper is that the FAA
> announced (last year) that they would not implement TIS in future radar
> upgrades, as a cost saving measure. This indicates to a lot of buyers
> that the FAA is not interesting in supporting the technology long term.
>
> I can't say I'm surprised. I've flown some TIS equipped aircraft
> and I think it's one of the best traffic avoidance technologies I've
> seen since TCAS. It figures that the FAA would choose to implement
> "cost savings" by deleting something that actually works and works
> well.

ADS-B makes TIS obsolete. No reason for the FAA to invest in two
different technologies. ADS-B holds a better future.

-Robert

[Larry Dighera]

On 28 Aug 2006 15:00:29 -0700, "John Galban" >
wrote in . com>:

>
> The reason that GTX330 sales are in the dumper is that the FAA
>announced (last year) that they would not implement TIS in future radar
>upgrades, as a cost saving measure. This indicates to a lot of buyers
>that the FAA is not interesting in supporting the technology long term.
>
> I can't say I'm surprised. I've flown some TIS equipped aircraft
>and I think it's one of the best traffic avoidance technologies I've
>seen since TCAS. It figures that the FAA would choose to implement
>"cost savings" by deleting something that actually works and works
>well.


Isn't the FAA committed to ADS-B? If so, isn't TIS-B likely to
replace TIS, or is TIS-B backwards compatible with TIS?

[Mike Schumann]

The FAA should be deploying ADS-B more agressively, so that people don't
continue to waste there money on transponders that are going to be obsolete
in 10 years.

Mike Schumann

"Robert M. Gary" > wrote in message
ups.com...
>
> John Galban wrote:
>> wrote:
>
>> The reason that GTX330 sales are in the dumper is that the FAA
>> announced (last year) that they would not implement TIS in future radar
>> upgrades, as a cost saving measure. This indicates to a lot of buyers
>> that the FAA is not interesting in supporting the technology long term.
>>
>> I can't say I'm surprised. I've flown some TIS equipped aircraft
>> and I think it's one of the best traffic avoidance technologies I've
>> seen since TCAS. It figures that the FAA would choose to implement
>> "cost savings" by deleting something that actually works and works
>> well.
>
> ADS-B makes TIS obsolete. No reason for the FAA to invest in two
> different technologies. ADS-B holds a better future.
>
> -Robert
>

[Ron Natalie]

Mike Schumann wrote:
> The FAA should be deploying ADS-B more agressively, so that people don't
> continue to waste there money on transponders that are going to be obsolete
> in 10 years.
>
The mode S transponders still have things to recommend them other than
TIS, though TIS was a major driving factor in my selecting one.

[Gig 601XL Builder]

"Robert M. Gary" > wrote in message
ups.com...
>
> John Galban wrote:
>> wrote:
>
>> The reason that GTX330 sales are in the dumper is that the FAA
>> announced (last year) that they would not implement TIS in future radar
>> upgrades, as a cost saving measure. This indicates to a lot of buyers
>> that the FAA is not interesting in supporting the technology long term.
>>
>> I can't say I'm surprised. I've flown some TIS equipped aircraft
>> and I think it's one of the best traffic avoidance technologies I've
>> seen since TCAS. It figures that the FAA would choose to implement
>> "cost savings" by deleting something that actually works and works
>> well.
>
> ADS-B makes TIS obsolete. No reason for the FAA to invest in two
> different technologies. ADS-B holds a better future.
>
> -Robert
>

The problem is that TIS is much easier and less expensive to put in an
aircraft. I can spend about 6 AMUs and have TIS along with a really nice
X-ponder, GPS, XM WX and all the other goodies provided by a Garmin 496.
There isn't room in my aircraft for any current ADS-B ability.

[Andrew Gideon]

On Mon, 28 Aug 2006 15:23:17 -0700, Robert M. Gary wrote:

> No reason for the FAA to invest in two different
> technologies.

From my reading, it appears that ADS-B is itself three different
technologies (ie. there are three different models of transceivers). If
so, the claimed peer-peer capability of ADS-B will be limited.

- Andrew

[Matt Barrow]

"Ron Natalie" > wrote in message
m...
> Mike Schumann wrote:
>> The FAA should be deploying ADS-B more agressively, so that people don't
>> continue to waste there money on transponders that are going to be
>> obsolete in 10 years.
>>
> The mode S transponders still have things to recommend them other than
> TIS,

Such as?

> though TIS was a major driving factor in my selecting one.

Is it worth the doubling of the price for a transponder?

[[email protected]]

Robert M. Gary wrote:
> I assume you are saying that your TIS goes into "coast mode" and stops
> updating for a period of time.

No. The box recognizes that it's being interrogated by the radar and
it responds with altitude data. It's programmed to display when the
mode S data does not contain TIS. That's the issue. TIS information
has been unavailable for as long as months at a time in Seattle. It
has been my experience that it is "rarely" available currently. I
would be interested to know if this is isolated to the NW or if the
entire country experiences this?

I would love to have ADS-B (the current name appears to be TIS-2). It
cost us $1000 to put TIS in the plane since we had the 430 and were
going to purchase a new transponder anyway. The Feds are still
thrashing around with the specs for the new TIS but currently politics
seem to be pushing to use the current spectrum which is too congested
to handle all the data. Sad but true.

A flight in the Seattle area will routinely put you in conflict with
dozens of other aircraft. We have congested airspace and mountains
that put a lot of VFR traffic in a small space. If TIS was only useful
for a year or two I'd consider it worthwhile. The Feds have indicated
that deployment of ADS-B in our area is a decade away.

Thanks,
Dave

[Peter R.]

> wrote:

> If TIS was only useful
> for a year or two I'd consider it worthwhile. The Feds have indicated
> that deployment of ADS-B in our area is a decade away.

I routinely fly across NY state and all the class C airports from western
to central and onto eastern NY offer TIS. Two years ago I installed the
Garmin GTX330 transponder that displays TIS traffic on an MX20 and GNS430.
It is definitely worthwhile in these areas.

--
Peter

[Gig 601XL Builder]

Here's a good TIS map that includes the ones scheduled to be shut down.

http://www.garmin.com/aviation/tis.jsp

[Peter R.]

Gig 601XL Builder <wrDOTgiaconaATcox.net> wrote:

> Here's a good TIS map that includes the ones scheduled to be shut down.
>
> http://www.garmin.com/aviation/tis.jsp

Yep, a lot of my flying is in that big blue blob over the northeast US so
TIS serves my well.

--
Peter

[Andrew Gideon]

On Tue, 29 Aug 2006 10:45:03 -0400, Peter R. wrote:

> Yep, a lot of my flying is in that big blue blob over the northeast US so
> TIS serves my well.

But the question facing me (and my fellow partners): would you buy TIS
*today* given the FAA's emphasis on ADS-B and TIS-B?

Note that they just brought online more of PA:

http://www.flttechonline.com/Current/Pennsylvania%20ADS-B%20Network%20Continues%20to%20Expand.htm
http://www.aopa.org/whatsnew/newsitems/2006/060817ads-b.html

- Andrew
http://flyingclub.org/

[Doug Vetter]

Andrew Gideon wrote:
> On Tue, 29 Aug 2006 10:45:03 -0400, Peter R. wrote:
>
>> Yep, a lot of my flying is in that big blue blob over the northeast US so
>> TIS serves my well.
>
> But the question facing me (and my fellow partners): would you buy TIS
> *today* given the FAA's emphasis on ADS-B and TIS-B?
<snip>

The question isn't whether you should buy TIS. It's whether you should
buy a Mode-S transponder, because that's the primary difference between
the 327 and 330. TIS is just a perk of moving to Mode-S, and it was
specifically designed that way to encourage pilots to move to Mode-S
when it became clear they would not otherwise willingly adopt the new,
more costly, technology.

The FAA is continuing to invest in Mode-S radars (the ASR-11 is
replacing the ASR 7, 8, and 9 units that currently support TIS), so an
investment in the airborne component is still a wise move and will be
for MANY years.

Oh, and don't believe the hype out of Blakley's mouth for a second.
ADS-B is not being deployed so they can "decommission radar". That will
not happen in our lifetime due to security concerns. I fear that the
*real* reason the FAA is pushing ADS-B is for billing purposes. With
the kind of reliable and accurate position data facilitiated by ADS-B,
they could charge us by the mile.

-Doug

--------------------
Doug Vetter, ATP/CFI

http://www.dvatp.com
--------------------

[Larry Dighera]

On Tue, 29 Aug 2006 23:34:27 -0400, Doug Vetter >
wrote in >:

>Oh, and don't believe the hype out of Blakley's mouth for a second.
>ADS-B is not being deployed so they can "decommission radar". That will
>not happen in our lifetime due to security concerns.

I'm happy to hear, that someone thought about that. It would be a
simple matter to spoof the positional data I would think.

>I fear that the *real* reason the FAA is pushing ADS-B is for billing purposes.

I would guess the reason has as much to do with compatibility with the
ATC system products of Boeing and LockMart.

>With the kind of reliable and accurate position data facilitiated by ADS-B,
>they could charge us by the mile.

Not if we don't let Congress out of oversight responsibilities for FAA
funding.

[Andrew Gideon]

On Tue, 29 Aug 2006 23:34:27 -0400, Doug Vetter wrote:

> The FAA is continuing to invest in Mode-S radars (the ASR-11 is replacing
> the ASR 7, 8, and 9 units that currently support TIS), so an investment in
> the airborne component is still a wise move and will be for MANY years.

Aside from TIS, what is the benefit (either to the pilot or ATC) of mode S?

- Andrew

[Newps]

>
>
>>The FAA is continuing to invest in Mode-S radars (the ASR-11 is replacing
>>the ASR 7, 8, and 9 units that currently support TIS),



11's are not replacing 9's. They are a stripped down 9.



so an investment in
>>the airborne component is still a wise move and will be for MANY years.


The FAA is installing new radars but they leave out the software that
supports TIS. That's what happened to us. We had a 7 with mode S and
TIS was operastional. We upgraded the radar to an 11 but they do not
install TIS stuff in the radar.

[Newps]

Andrew Gideon wrote:


>
>
> Aside from TIS, what is the benefit (either to the pilot or ATC) of mode S?


To ATC? Nuthin' I wouldn't know if you had one.

[Bob Noel]

In article >,
Newps > wrote:

>
> 11's are not replacing 9's. They are a stripped down 9.

I don't recall the ARS-11 being a derivative of the -9.

--
Bob Noel
Looking for a sig the
lawyers will hate

[Newps]

Bob Noel wrote:

> In article >,
> Newps > wrote:
>
>
>>11's are not replacing 9's. They are a stripped down 9.
>
>
> I don't recall the ARS-11 being a derivative of the -9.


It's the K Mart version of the 9.

[Mark Manes]

Mode S has several advantages. ATC interrogation pulses can be directed to
a specific aircraft or all Mode S aircraft. Replies to the interrogation
can contain specific information (altitude, aircraft ID and airframe type).
Interrogation to all Mode S aircraft could illicit a reply from my Garmin
GTX 330 that contians my tail # and type and altitude. I don't know if all
of this is currently functional in any or all of the Mode S facilities or
not but this was the original intent.

http://rfdesign.com/military_defense_electronics/radio_understanding_mode_technology/I think that it's a great thought that will give way to ADS-B. TIS is agreat tool also that will probably pass by the wayside. But my 2 or 3 tripsper month into the Dallas Class B are made easier with TIS. FSM where I'mbased had TIS for the first year after I installed the Garmin but theyupgraded the radar (to ASR 11, I believe) and are not going to turn TIS onfor whatever reason.MarkN28409WC5I"Andrew Gideon" > wrote in messagenews:pan.2006.08.30.23.39.09.697508@gideon. org...> On Tue, 29 Aug 2006 23:34:27 -0400, Doug Vetter wrote:>>> The FAA is continuing to invest in Mode-S radars (the ASR-11 is replacing>> the ASR 7, 8, and 9 units that currently support TIS), so an investmentin>> the airborne component is still a wise move and will be for MANY years.>> Aside from TIS, what is the benefit (either to the pilot or ATC) of modeS?>> - Andrew>

[Thomas Borchert]

Newps,

> To ATC? Nuthin' I wouldn't know if you had one.
>

Ah, the broad view of the American ;-)

In Europe, Mode S equipment is becoming mandatory solely for ATC
reasons. There is no TIS here. ATC stations with the proper equipment
can do "selective" calls (hence mode S) interrogating only specific
aircraft. This leads to less congestion on the secondary radar
frequency, which, Eurocontrol tells us, is a serious problem with Mode
A/C. They claim to be running out of transponder codes, for example.
More info via google...

--
Thomas Borchert (EDDH)

[Bob Noel]

In article <9rrJg.24072$W01.11777@dukeread08>, "Mark Manes" >
wrote:

> Mode S has several advantages. ATC interrogation pulses can be directed to
> a specific aircraft or all Mode S aircraft.

I know the advantages from an ATC POV, but what is the advantage for
the aircraft owner?

--
Bob Noel
Looking for a sig the
lawyers will hate

[Stefan]

Bob Noel schrieb:

> I know the advantages from an ATC POV, but what is the advantage for
> the aircraft owner?

To be allowed to fly in controlled airspace at all? In Europe, Mode S
will be mandated, because ATC claims Mode C reaches its limits. This
means in the forseeable future: No Mode S, no fly in controlled airspace.

Stefan

[Larry Dighera]

On Thu, 31 Aug 2006 12:52:11 +0200, Stefan >
wrote in >:

>Bob Noel schrieb:
>
>> I know the advantages from an ATC POV, but what is the advantage for
>> the aircraft owner?
>
>To be allowed to fly in controlled airspace at all? In Europe, Mode S
>will be mandated, because ATC claims Mode C reaches its limits. This
>means in the forseeable future: No Mode S, no fly in controlled airspace.
>

Would that Mode S requirement be a result of the implement ion of
outsource ATC?

[Ron Lee]

Stefan > wrote:

>Bob Noel schrieb:
>
>> I know the advantages from an ATC POV, but what is the advantage for
>> the aircraft owner?
>
>To be allowed to fly in controlled airspace at all? In Europe, Mode S
>will be mandated, because ATC claims Mode C reaches its limits. This
>means in the forseeable future: No Mode S, no fly in controlled airspace.
>
>Stefan

We will see. Such a mandate will meet considerable opposition. Same
as GA user fees. Heck, the FAA has not even started any sort of 406
MHh ELT mandate to my knowledge. (USA applicability)

Ron Lee

[Stefan]

Larry Dighera schrieb:

> Would that Mode S requirement be a result of the implement ion of
> outsource ATC?

No, why should it? Mode S implementation is very expensive for ATC. It's
as I said: They say that in certain regions iof Europe, Mode C reaches
its limits. As I don't know anything about it, I have to believe it.

From http://www.eurocontrol.int/msa/public/faq/faq.html:
Mode S is being deployed because the current SSR systems have reached
the limit of their operational capability. This takes the form of
exceeded maximum number of targets, RF pollution, lost targets, identity
errors and Mode A code shortage. Mode S is therefore a necessary SSR
replacement in airspace subject to high levels of traffic density.

Stefan

[Thomas Borchert]

Ron,

> We will see. Such a mandate will meet considerable opposition.
>

Not in Europe. We have seen, here. It has met considerable opposition -
and has been mandated nonetheless.

--
Thomas Borchert (EDDH)

[Morgans[_4_]]

"Mark Manes" > wrote

FSM where I'mbased had TIS for the first year after I installed the Garmin
but theyupgraded the radar (to ASR 11, I believe) and are not going to turn
TIS onfor whatever reason.MarkN28409WC5I"Andrew Gideon" >
wrote in messagenews:pan.2006.08.30.23.39.09.697508@gideon. org...> On Tue,
29 Aug 2006 23:34:27 -0400, Doug Vetter wrote:>>> The FAA is continuing to
invest in Mode-S radars (the ASR-11 is replacing>> the ASR 7, 8, and 9 units
that currently support TIS), so an investmentin>> the airborne component is
still a wise move and will be for MANY years.>> Aside from TIS, what is the
benefit (either to the pilot or ATC) of modeS?>> - Andrew>

Dood, buy a space, or sumpthin' ! <g>
--
Jim in NC

[Andrew Gideon]

On Thu, 31 Aug 2006 16:47:21 +0200, Stefan wrote:

> Mode S is being deployed because the current SSR systems have reached the
> limit of their operational capability. This takes the form of exceeded
> maximum number of targets, RF pollution, lost targets, identity errors and
> Mode A code shortage. Mode S is therefore a necessary SSR replacement in
> airspace subject to high levels of traffic density.

I've some difficulty understanding this.

From reading here, I've been lead to believe that aviation is more common
in the US than in the EU. Given this, I have to assume that a locality
like the KEWR/KLGA/KJJK area would have a higher aircraft density than
anywhere in Europe.

No?

If so, then how can a locality like that not be suffering from the same
problem as that described in the cited text? I fly in this area, and I've
never noted identity errors nor have I ever been denied service due to an
insufficiency of mode A codes.

- Andrew

[Bob Noel]

In article >,
Stefan > wrote:

> > I know the advantages from an ATC POV, but what is the advantage for
> > the aircraft owner?
>
> To be allowed to fly in controlled airspace at all? In Europe, Mode S
> will be mandated, because ATC claims Mode C reaches its limits. This
> means in the forseeable future: No Mode S, no fly in controlled airspace.

Sorry. I should have clarified that my question was applicable to the US NAS.
I do understand the European requirements for Mode S, 8.33, ACAS, etc etc.
But in the US, Mode S is still just a solution looking for a problem.

--
Bob Noel
Looking for a sig the
lawyers will hate

[Doug Vetter]

Andrew Gideon wrote:
> On Tue, 29 Aug 2006 23:34:27 -0400, Doug Vetter wrote:
>
>> The FAA is continuing to invest in Mode-S radars (the ASR-11 is replacing
>> the ASR 7, 8, and 9 units that currently support TIS), so an investment in
>> the airborne component is still a wise move and will be for MANY years.
>
> Aside from TIS, what is the benefit (either to the pilot or ATC) of mode S?
>
> - Andrew

Here are a few advantages of Mode-S over Mode-A:

1) Selective interrogations. Because the mode-s airborne component has
a unique address, any ground or airborne interrogator may request your
particular transponder (and only your transponder) to reply. It learns
your unique ID by using a broadcast request called "all call".

This is helpful on a technical level where the radar is attempting to
acquire the position of many aircraft that may be on or near the same
radial from the radar site (say, for example, three aircraft on the 237
radial from the radar antenna at 5, 10, and 40 miles away). The result
is less of a chance for ghosting and other radar anomalies. For
example, I used to have a problem when talking to Phili approach near
the Yardley VOR where they used to report a ghost image of my aircraft
about a mile away. They haven't reported the problem since I upgraded
to Mode-S.

This increases the distance at which a transponder may be identified
(thus increasing the effective range of the radar) because the site can
keep the aircraft at 5 and 10 miles quiet while it listens for a reply
from the aircraft 40 miles out. There are some practical limitations to
this benefit, mostly caused by the continued use of mode-a transponders,
but hopefully that won't be the case forever.

2) Support for Ground mode, which replies only with the unique ID
(Mode-S ID or Tail Number) and a software flag that tells the
interrogator the unit is on the ground. It does NOT respond with the
currently-entered squawk code (1200 or otherwise).

This is a nice feature simply because it helps identify your aircraft to
ground radar (like that deployed for testing at Providence, RI), and
because it prevents the need to turn the transponder off to prevent
squawking an old code after landing (most important to IFR pilots).

The great thing about the 330 in particular is that the unit switches
modes automatically based on either a landing gear position switch or
(in the case of our fixed gear 172) the speed of the aircraft as derived
from a GPS' serial data interface. It even knows whether to switch from
ALT to GND or from ALT to STBY, based on recent activity, or so said a
Garmin tech rep.

3) Although this is not unique to the 330 or Mode-S, I mention it
because I've seen the test results with my own eyes on my 330 --
specifically, the ability to respond to a interrogation rate at 100% of
the theoretical maximum, while most older "analog" transponders can only
manage 40% of that rate before becoming saturated.

The ability of a transponder to handle a high reply rate will become
more important as more aircraft are equipped with systems such as TCAS
and Skywatch that actively interrogate targets much in the same way
ground facilities do.

For more info, check out the 330 review on my site. Click through:

Aviation->Articles->Reviews->Garmin 396

-Doug

--------------------
Doug Vetter, ATP/CFI

http://www.dvatp.com
--------------------

[Thomas Borchert]

Andrew,

> If so, then how can a locality like that not be suffering from the same
> problem as that described in the cited text?
>

Excellent question. That's why many have doubts about Eurocontrol's
claims. But it's all too late...

--
Thomas Borchert (EDDH)

[Andrew Gideon]

On Thu, 31 Aug 2006 23:32:47 -0400, Doug Vetter wrote:

> The ability of a transponder to handle a high reply rate will become more
> important as more aircraft are equipped with systems such as TCAS and
> Skywatch that actively interrogate targets much in the same way ground
> facilities do.

Let's assume that a [mode c] transponder is being interrogated at a rate
higher than that at which it can respond. Does this matter? If the
transponder is responding as quickly as it can (let's pick a hypothetic
10/second), while it is receiving [a hypothetic] 20 interrogations/second,
won't each interrogator still see the 10 responses per second and
therefore "see" responses to its own interrogations?

Or is there some unique mapping from a specific interrogation to the
specific reply?

- Andrew

[Larry Dighera]

On Thu, 31 Aug 2006 16:47:21 +0200, Stefan >
wrote in >:

>Larry Dighera schrieb:
>
>> Would that Mode S requirement be a result of the implemention of
>> outsource ATC?
>
>No, why should it?

Because the corporation providing ATC services under contract to the
government(s) thinks it's a good idea?

>Mode S implementation is very expensive for ATC.

Perhaps the ATC contractor can get the funds necessary to implement
Mode S equipment installation from the government(s), and then use the
added functionality provided by Mode S to enhance their revenue stream
in the future.

>It's as I said: They say that in certain regions iof Europe, Mode C reaches
>its limits. As I don't know anything about it, I have to believe it.

Either believe it, or do the research necessary to verify the
allegation.

> From http://www.eurocontrol.int/msa/public/faq/faq.html:
>Mode S is being deployed because the current SSR systems have reached
>the limit of their operational capability. This takes the form of
>exceeded maximum number of targets, RF pollution, lost targets, identity
>errors and Mode A code shortage. Mode S is therefore a necessary SSR
>replacement in airspace subject to high levels of traffic density.
>

Can European airspace possibly be more congested than that in the US,
say Chicago or Los Angeles?

[Stefan]

Larry Dighera schrieb:

>> No, why should it?

> Because the corporation providing ATC services under contract to the
> government(s) thinks it's a good idea?

Obviously, they do.

> Either believe it, or do the research necessary to verify the
> allegation.

In this particular case, I choose to believe it. You can handle it als
you want.

Stefan

[Stefan]

Andrew Gideon schrieb:

> I've some difficulty understanding this.
>
> From reading here, I've been lead to believe that aviation is more common
> in the US than in the EU. Given this, I have to assume that a locality
> like the KEWR/KLGA/KJJK area would have a higher aircraft density than
> anywhere in Europe.
>
> No?

Frankly, I don't know. No doubt there will be some spam can drivers who
know as little as I do about ATC who will tell you that the specialists
at Eurocontrol have no clue, that everything is better elsewhere and
that Eurocontrol's agenda is to stop all aviation in Europe anyway... an
attitude which is pretty much en vogue right now. I'm somewhat untypical
as I don't share this attitude. I frankly admit that I don't know enough
to judge their claim, so I have to believe it. I don't believe that
Eurocontrol is just a bunch of idiots and sadists.

Nonetheless some thoughts: The primary concern is not the number of
transponder codes. It's the fact that when lots of transponders which
are located near each other (angle wise) respond simultaneously, the
system breaks down. I don't have the exact numbers handy, but there is a
discrimination limit. And there have already been reports of lost
targets. (No, I won't go through the hassle to dig the report out, so
you can choose to believe or not believe in my memory.) There are some
parts in Europe which are surprisingly congested, and the airspace in
those parts tends to be extremely complex. Maybe Europeans just care
more about such lost targets than Americans? And then, they are not
saying that the traffic has already exceeded their capacity. They say it
will reach its limits soon. I think it's a responsible move to try to
proactively solve the problem before the system breaks down.

Stefan

[Bob Noel]

In article >,
Larry Dighera > wrote:

> Can European airspace possibly be more congested than that in the US,
> say Chicago or Los Angeles?

Enroute? yeah, I think so.

--
Bob Noel
Looking for a sig the
lawyers will hate

[Larry Dighera]

On Fri, 01 Sep 2006 22:02:46 -0400, Bob Noel
> wrote in
>:

>In article >,
> Larry Dighera > wrote:
>
>> Can European airspace possibly be more congested than that in the US,
>> say Chicago or Los Angeles?
>
>Enroute? yeah, I think so.

But surely the US terminal airspace is more congested.