Transponder Landing System ???

[Trent D. Sanders]

Have you ever heard of, or have any experience with a thing called the
"Transponder Landing System", a form of IFR approach using a
transponder? What is it, how does it work, does it work, do you have
to have a special "endorsement" to fly it, etc?

TDS
N2997Y

[Bob Gardner]

AIM 1-1-23. Special training is required.

Bob Gardner

"Trent D. Sanders" > wrote in message
om...
> Have you ever heard of, or have any experience with a thing called the
> "Transponder Landing System", a form of IFR approach using a
> transponder? What is it, how does it work, does it work, do you have
> to have a special "endorsement" to fly it, etc?
>
> TDS
> N2997Y

[kage]

I have flown the demonstrator that was set up at Madras. A couple of
corporate operators were going to get together and buy one for Sun Valley.

I don't think that ever happened. It takes a controller on the ground with
the equipment and you get a special squawk and just fly it like any other
ILS.

Curved approaches are possible. There was military application as well. The
unit could be parachuted out and set up in 30 minutes to a remote location.

Karl




"Trent D. Sanders" > wrote in message
om...
> Have you ever heard of, or have any experience with a thing called the
> "Transponder Landing System", a form of IFR approach using a
> transponder? What is it, how does it work, does it work, do you have
> to have a special "endorsement" to fly it, etc?
>
> TDS
> N2997Y

[Frank Stutzman]

kage > wrote:
> I have flown the demonstrator that was set up at Madras. A couple of
> corporate operators were going to get together and buy one for Sun Valley.

There was also a demonstrator set up at The Dalles airport (DLS) for a
while. The company working on this is Advanced Navigation Positioning
Systems (www.anpc.com) of Hood River, OR. According to their web site,
they have 4 sites where it is installed and a dozen or so planned. I'm
not sure what installed means as the DLS one is considered "installed",
but it certainly not an approved approach. Ditto for Pullman, WA.

I flew the approach DLS approach under VFR. Seemed to work ok. I'm not
sure what special training would be required. You have to talk to a
controller on the ground and get a transponder code. After that, tune
your radio to the right frequency and follow the needles. The Dalles
approach was an normal dme arc that put you onto the TLS straight-in
approach course. A curving TLS approach could be interesting.


--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

[Gerry Caron]

TLS is a substitute for an ILS where an ILS can't be installed due to
terrain or other factors. It's also a whole lot cheaper than an ILS so it's
useful for smaller airports. That's good, because it's capacity limited
(more later) so it's not a good solution for busy airports.
It works by using a Mode A interrogator and multiple receivers around the
periphery of the airport. By measuring the time difference of arrival
(TDOA) of your transponder replies, it calculates your position relative to
the airport and the approach path. It then broadcasts thru an omni antenna
an "ILS" signal modulating the 90 and 150 Hz tones to drive your CDI to
indicate the proper guidance to the approach path.
To fly it, you have to set your transponder to the squawk code on the
approach plate (so it knows who is flying the approach) and tune your ILS
receiver to the "ILS" freq. The you fly it just like an ILS approach. No
special endorsements or training.
The capacity limitation I mentioned above comes about because only one a/c
can have the approach squawk code set at any one time or the system will get
confused and flag.
I haven't flown one. Most are in the pacific northwest at small airports in
the mountains.
Try the following link:
http://anpc.com/

Gerry


"Trent D. Sanders" > wrote in message
om...
> Have you ever heard of, or have any experience with a thing called the
> "Transponder Landing System", a form of IFR approach using a
> transponder? What is it, how does it work, does it work, do you have
> to have a special "endorsement" to fly it, etc?
>
> TDS
> N2997Y

[john smith]

Lousy website!
You have to use MSIE to access it!

Gerry Caron wrote:
> Try the following link:
> http://anpc.com/

[J Haggerty]

TLS is a system that was originally conceived as a system with ILS CAT I
minima, but that didn't need the expensive siting and grading required
by a normal ILS system.
Right now it appears that the original 200' HAT that was hoped for is
being limited to a 350 HAT, at least temporarily. It is also considered
"special" so you won't see them on the approach plates and will need to
have special training and permission to fly it. FEDEX is using one in
the Phillipines, and FAA has one set up in Atlantic City.
The system still requires ILS equipment on board the aircraft, but also
requires an operator on the ground to acquire the transponder code and
operate the ground equipment.
Rather than try to explain it in my own words, check this website out
that has a good description;
http://avnwww.jccbi.gov/icasc/docs/12thifis/Application%20of%20the%20Transponder%20Landing%20S ystem%20to%20Achieve%20Airport%20Accessibility.doc

or;
http://www.gaavionics.com/tls.htm

JPH

Trent D. Sanders wrote:
> Have you ever heard of, or have any experience with a thing called the
> "Transponder Landing System", a form of IFR approach using a
> transponder? What is it, how does it work, does it work, do you have
> to have a special "endorsement" to fly it, etc?
>
> TDS
> N2997Y

[Mike Rapoport]

It isn't cheaper when you consider that it requires an operator.

Mike
MU-2


"Gerry Caron" > wrote in message
. ..
> TLS is a substitute for an ILS where an ILS can't be installed due to
> terrain or other factors. It's also a whole lot cheaper than an ILS so
> it's
> useful for smaller airports. That's good, because it's capacity limited
> (more later) so it's not a good solution for busy airports.
> It works by using a Mode A interrogator and multiple receivers around the
> periphery of the airport. By measuring the time difference of arrival
> (TDOA) of your transponder replies, it calculates your position relative
> to
> the airport and the approach path. It then broadcasts thru an omni
> antenna
> an "ILS" signal modulating the 90 and 150 Hz tones to drive your CDI to
> indicate the proper guidance to the approach path.
> To fly it, you have to set your transponder to the squawk code on the
> approach plate (so it knows who is flying the approach) and tune your ILS
> receiver to the "ILS" freq. The you fly it just like an ILS approach. No
> special endorsements or training.
> The capacity limitation I mentioned above comes about because only one a/c
> can have the approach squawk code set at any one time or the system will
> get
> confused and flag.
> I haven't flown one. Most are in the pacific northwest at small airports
> in
> the mountains.
> Try the following link:
> http://anpc.com/
>
> Gerry
>
>
> "Trent D. Sanders" > wrote in message
> om...
>> Have you ever heard of, or have any experience with a thing called the
>> "Transponder Landing System", a form of IFR approach using a
>> transponder? What is it, how does it work, does it work, do you have
>> to have a special "endorsement" to fly it, etc?
>>
>> TDS
>> N2997Y
>
>

[Everett M. Greene]

"Mike Rapoport" > writes:
> "Gerry Caron" > wrote
> > "Trent D. Sanders" > wrote

> >> Have you ever heard of, or have any experience with a thing called the
> >> "Transponder Landing System", a form of IFR approach using a
> >> transponder? What is it, how does it work, does it work, do you have
> >> to have a special "endorsement" to fly it, etc?

> > TLS is a substitute for an ILS where an ILS can't be installed due to
> > terrain or other factors. It's also a whole lot cheaper than an ILS so
> > it's useful for smaller airports. That's good, because it's capacity
> > limited (more later) so it's not a good solution for busy airports.

> > It works by using a Mode A interrogator and multiple receivers around the
> > periphery of the airport. By measuring the time difference of arrival
> > (TDOA) of your transponder replies, it calculates your position relative
> > to the airport and the approach path. It then broadcasts thru an omni
> > antenna an "ILS" signal modulating the 90 and 150 Hz tones to drive your
> > CDI to indicate the proper guidance to the approach path.

> > To fly it, you have to set your transponder to the squawk code on the
> > approach plate (so it knows who is flying the approach) and tune your ILS
> > receiver to the "ILS" freq. The you fly it just like an ILS approach. No
> > special endorsements or training.

> > The capacity limitation I mentioned above comes about because only one a/c
> > can have the approach squawk code set at any one time or the system will
> > get confused and flag.

> > I haven't flown one. Most are in the pacific northwest at small airports
> > in the mountains.

> > Try the following link: http://anpc.com/

> It isn't cheaper when you consider that it requires an operator.

The descriptions given above and other followups don't make it
clear: What's the function of the operator?

[Mike Rapoport]

You need an operator to asign codes to inbound aircraft (ATC was not going
to do this). Presumably the machine also need to get the code input. There
was talk about putting one in here at SZT but the operator issue killed it
along with comments by the FAA that the localizer would have to be removed.
The TLS was also only going to be approved for a limited number of users
(certainly not part 91 piston airplanes, after all they only comprise 90% of
the airplanes using the airport). It was also only going to be in use for a
limited number of hours per day (when the operator was present)

I think that the solution is precision GPS approaches.

Mike
MU-2


"Everett M. Greene" > wrote in message
...
> "Mike Rapoport" > writes:
>> "Gerry Caron" > wrote
>> > "Trent D. Sanders" > wrote
>
>> >> Have you ever heard of, or have any experience with a thing called the
>> >> "Transponder Landing System", a form of IFR approach using a
>> >> transponder? What is it, how does it work, does it work, do you have
>> >> to have a special "endorsement" to fly it, etc?
>
>> > TLS is a substitute for an ILS where an ILS can't be installed due to
>> > terrain or other factors. It's also a whole lot cheaper than an ILS so
>> > it's useful for smaller airports. That's good, because it's capacity
>> > limited (more later) so it's not a good solution for busy airports.
>
>> > It works by using a Mode A interrogator and multiple receivers around
>> > the
>> > periphery of the airport. By measuring the time difference of arrival
>> > (TDOA) of your transponder replies, it calculates your position
>> > relative
>> > to the airport and the approach path. It then broadcasts thru an omni
>> > antenna an "ILS" signal modulating the 90 and 150 Hz tones to drive
>> > your
>> > CDI to indicate the proper guidance to the approach path.
>
>> > To fly it, you have to set your transponder to the squawk code on the
>> > approach plate (so it knows who is flying the approach) and tune your
>> > ILS
>> > receiver to the "ILS" freq. The you fly it just like an ILS approach.
>> > No
>> > special endorsements or training.
>
>> > The capacity limitation I mentioned above comes about because only one
>> > a/c
>> > can have the approach squawk code set at any one time or the system
>> > will
>> > get confused and flag.
>
>> > I haven't flown one. Most are in the pacific northwest at small
>> > airports
>> > in the mountains.
>
>> > Try the following link: http://anpc.com/
>
>> It isn't cheaper when you consider that it requires an operator.
>
> The descriptions given above and other followups don't make it
> clear: What's the function of the operator?

[C Kingsbury]

"Gerry Caron" > wrote in message >...

> It works by using a Mode A interrogator and multiple receivers around the
> periphery of the airport. By measuring the time difference of arrival
> (TDOA) of your transponder replies, it calculates your position relative to
> the airport and the approach path. It then broadcasts thru an omni antenna
> an "ILS" signal modulating the 90 and 150 Hz tones to drive your CDI to
> indicate the proper guidance to the approach path.

Fascinating the things people thought up back in the days before a
constellation of satellites could provide a 3D positional fix with an
accuracy measured in inches.

With WAAS underway, it seems predictable that non-precision approaches
will be joining colored airways in the dustbin of history. If the FAA
had the resources and motivation it could probably be accomplished in
5 years, though I suppose 20 is more likely...

-cwk.

[C Kingsbury]

"Mike Rapoport" > wrote in message .net>...

> It isn't cheaper when you consider that it requires an operator.
>
> Mike
> MU-2

Does it require a dedicated operator, or can any old controller
hanging out in the tower run it? Out East I can't think of any Class D
fields that don't have at least 1 ILS, but perhaps in other regions
that's sometimes the case?

-cwk.

[John R. Copeland]

"C Kingsbury" > wrote in message =
om...
> "Gerry Caron" > wrote in message =
>...
>=20
>> It works by using a Mode A interrogator and multiple receivers around =
the
>> periphery of the airport. By measuring the time difference of =
arrival
>> (TDOA) of your transponder replies, it calculates your position =
relative to
>> the airport and the approach path. It then broadcasts thru an omni =
antenna
>> an "ILS" signal modulating the 90 and 150 Hz tones to drive your CDI =
to
>> indicate the proper guidance to the approach path.
>=20
> Fascinating the things people thought up back in the days before a
> constellation of satellites could provide a 3D positional fix with an
> accuracy measured in inches.
>=20
> With WAAS underway, it seems predictable that non-precision approaches
> will be joining colored airways in the dustbin of history. If the FAA
> had the resources and motivation it could probably be accomplished in
> 5 years, though I suppose 20 is more likely...
>=20
> -cwk.

Five years? Twenty years?
Probably about a year ago, the FAA mentioned the rate at which they were
converting (IIRC) GPS approaches to LNAV/VNAV approaches.
The number sounded fairly good, until doing the math showed it would =
take
them about thirty years to finish the current number of runways at that =
rate.
---JRC---

[Mike Rapoport]

A tower controller could do it but, like you say, there aren't many towered
fields without a low minimiums approach and no terrain issues. Generally it
is terrain that limits minimiums.

Mike
MU-2


"C Kingsbury" > wrote in message
om...
> "Mike Rapoport" > wrote in message
> .net>...
>
>> It isn't cheaper when you consider that it requires an operator.
>>
>> Mike
>> MU-2
>
> Does it require a dedicated operator, or can any old controller
> hanging out in the tower run it? Out East I can't think of any Class D
> fields that don't have at least 1 ILS, but perhaps in other regions
> that's sometimes the case?
>
> -cwk.

[Michael]

"Mike Rapoport" > wrote
> It isn't cheaper when you consider that it requires an operator.

It doesn't require a DEDICATED operator. There is no reason that the
squawk code could not be issued by the approach/center controller.
Typically, a non-busy airport would have no tower or a VFR tower, so
one-in, one-out. The code could be set by a remote landline from
approach/center, or it could simply use a fixed discrete code that
would not be used for other purposes in that sector.

Michael

[Mike Rapoport]

Could be, would be, should be...whatever the case, the SZT airport was going
to have to hire a DEDICATED operator. Most uncontrolled fields around here
don't even have a RCO. In theory, I'm sure that you are right.

Mike
MU-2


"Michael" > wrote in message
om...
> "Mike Rapoport" > wrote
>> It isn't cheaper when you consider that it requires an operator.
>
> It doesn't require a DEDICATED operator. There is no reason that the
> squawk code could not be issued by the approach/center controller.
> Typically, a non-busy airport would have no tower or a VFR tower, so
> one-in, one-out. The code could be set by a remote landline from
> approach/center, or it could simply use a fixed discrete code that
> would not be used for other purposes in that sector.
>
> Michael

[Andrew Gideon]

C Kingsbury wrote:

> Out East I can't think of any Class D
> fields that don't have at least 1 ILS, but perhaps in other regions
> that's sometimes the case?

<Sniff> Now you've made me feel badly about my home class D airport in
Northern New Jersey, CDW, that has no precision approach (but we do have a
localizer).

I'd feel really badly did I not know that Hartford, in CT, also lacks a
precision approach. They don't even have a localizer; just an LDA.

[I think that this LDA lets you off pointing not at the airport, but at a
now closed airport across a river. But I may be recalling incorrectly.]

- Andrew

[Roy Smith]

In article e.com>,
Andrew Gideon > wrote:

> C Kingsbury wrote:
>[i]
> > Out East I can't think of any Class D
> > fields that don't have at least 1 ILS, but perhaps in other regions
> > that's sometimes the case?
>
> <Sniff> Now you've made me feel badly about my home class D airport in
> Northern New Jersey, CDW, that has no precision approach (but we do have a
> localizer).
>
> I'd feel really badly did I not know that Hartford, in CT, also lacks a
> precision approach. They don't even have a localizer; just an LDA.
>
>
>
> - Andrew

In addition to Hartford and Caldwell, there's also Danburry which only
has a localizer.

[Michael]

"Mike Rapoport" > wrote
> Could be, would be, should be...whatever the case, the SZT airport was going
> to have to hire a DEDICATED operator. Most uncontrolled fields around here
> don't even have a RCO. In theory, I'm sure that you are right.

The difference between theory and practice is much greater in practice
than it is in theory.

The real issue is that what started as a good idea had to get by the
FAA.

Michael

[Mike Rapoport]

"Michael" > wrote in message
om...
> "Mike Rapoport" > wrote
>> Could be, would be, should be...whatever the case, the SZT airport was
>> going
>> to have to hire a DEDICATED operator. Most uncontrolled fields around
>> here
>> don't even have a RCO. In theory, I'm sure that you are right.
>
> The difference between theory and practice is much greater in practice
> than it is in theory.
>
> The real issue is that what started as a good idea had to get by the
> FAA.
>

Exactly.

Mike
MU-2

> Michael

[C Kingsbury]

Roy Smith > wrote in message >...
> In article e.com>,
> Andrew Gideon > wrote:
>
> > C Kingsbury wrote:
> >[i]
> > > Out East I can't think of any Class D
> > > fields that don't have at least 1 ILS, but perhaps in other regions
> > > that's sometimes the case?
> >
> > <Sniff> Now you've made me feel badly about my home class D airport in
> > Northern New Jersey, CDW, that has no precision approach (but we do have a
> > localizer).
> >
> > I'd feel really badly did I not know that Hartford, in CT, also lacks a
> > precision approach. They don't even have a localizer; just an LDA.
> >
> >
> >
> > - Andrew
>
> In addition to Hartford and Caldwell, there's also Danburry which only
> has a localizer.

Duh, Beverly (BVY) which I've flown into also has a localizer-only approach.

Post first, think later...

Best,
-cwk.

[Richard Kaplan]

"C Kingsbury" > wrote in message
om...

> With WAAS underway, it seems predictable that non-precision approaches
> will be joining colored airways in the dustbin of history. If the FAA

This is unlikely when one considers that a number of airports which
currently have WAAS approaches have non-precision minimums which are lower
than the WAAS minimums.

Also consider that WAAS approaches can only be designed to airports clear of
obstructions according to TERPS; thus lots of airports will remain eligible
only for non-precision approaches.

--------------------
Richard Kaplan

www.flyimc.com

[Barry]

> This is unlikely when one considers that a number of airports which
> currently have WAAS approaches have non-precision minimums
> which are lower than the WAAS minimums.

Do you have some examples?

[C Kingsbury]

"Richard Kaplan" > wrote in message news:<1095562995.6eAYDxNjAfSfAEnPws5pJw@teranews>...
> "C Kingsbury" > wrote in message
> om...
>
> > With WAAS underway, it seems predictable that non-precision approaches
> > will be joining colored airways in the dustbin of history. If the FAA
>
> This is unlikely when one considers that a number of airports which
> currently have WAAS approaches have non-precision minimums which are lower
> than the WAAS minimums.

Hmmm, is this just a matter of the TERPS guys being conservative until
WAAS is better understood? I can't see any case where WAAS provides
poorer positional accuracy than a VOR, and it should at least be very
close to the performance of a localizer.

> Also consider that WAAS approaches can only be designed to airports clear of
> obstructions according to TERPS; thus lots of airports will remain eligible
> only for non-precision approaches.
>

Heh. Good point, I hadn't thought about that so much.

Actually, an interesting case-study can be seen looking at the
different approaches for Rutland, VT
(http://www.airnav.com/airport/KRUT) which is down in a valley with a
gaggle of towers. With its proximity to several major ski resorts it
gets a fair deal of light bizjet traffic.

Approach | Minima AGL (all straight-in)
===========|=============
LOC 19 | 2100
VOR-DME 19 | 1800
GPS 19 | 1400
LOC+DME 19 | 900

According to these plates, the angle of descent in the final segment
ranges between 3.35-3.72 degrees, as compared to a 3deg standard ILS.

Is there any reason why using WAAS, it wouldn't help to basically
setup a virtual glideslope that brings the plane down to the minimum
at the appropriate point, and then "levels off" until the missed
approach point? Well, other than the fact that perhaps no one has
thought about designing such a procedure, I suppose...

Still, at the very least every airport should be able to support
minimums equivalent to those that would be provided by a LOC-DME
installation. You can't change the dictates of terrain but at least
you don't have to pay to install and maintain a shed full of radio
equipment.

Best,
-cwk.