TLS - Transponder Landing System

[flyingcheesehead]

Wow, hadn't heard of this before: Transponder Landing System. Seems like a good idea, as it works with existing aircraft equipment (transponder + ILS receivers) and can be used in places where an ILS can't, plus it should be cheaper to install and maintain...

But the FAA doesn't publish any plates for TLS approaches, and they're all privately operated? WTF? This could be very useful and cost-effective, and the FAA is totally ignoring it. Sheesh.

FWIW, KRYV (Watertown, WI) has a TLS approach, or so I hear... I just don't know how to use it without a plate.

 

[tonycondon]

interesting kent, i wonder how much the equipment costs.

 

[jdwatson]

JeppView didn't have a TLS plate for Watertown (KRYV) either.

 

[jdwatson]

After readining the Wiki, I think I like WAAS better.

 

[tonycondon]

why??

 

[flyersfan31]

At first I thought it was an April Fool's joke. That's pretty interesting. The Watertown airport website brags that its installation is the first TLS in the country, but no info on the approach itself. Probably need to talk to the airport? Or just dial in the VOR?

 

[N50909]

The fact that you have to set your tranponder "to the correct code" seems like a logistical issue to me. How's that gonna work with ATC?

 

[tonycondon]

uh they assign you the code???? it is possible that they keep that code reserved for people shooting that approach. not that tricky

"N1234, reset transponder, squawk 5678, cleared TLS approach KRYV"

 

[N50909]

uh they assign you the code???? it is possible that they keep that code reserved for people shooting that approach. not that tricky

"N1234, reset transponder, squawk 5678, cleared TLS approach KRYV"

Then if/when you go missed do you need a new code/clearance 'cuz your old data block based on your original code is toast?

 

[tonycondon]

i dont think so. no reason ATC cant keep your data with the new code, aFAIK. I often get transponder code changes from approach before a handoff to center when i arrange flight following with them. never seems to be a loss of information associated with that.

 

[jdwatson]

why??

The Wiki points out:

Drawbacks

Since the system locks on to a single aircraft's transponder then transmits a signal that is specific to that aircraft's location, only one aircraft at a time can fly the approach. Any other aircraft in the area will receive the same guidance regardless of their location relative to the approach.

Imagine a pilot has keyed in the wrong transponder code and is receiving guidance for another aircraft. At least with WAAS, the guidance a pilot is receiving is derived for the aircraft they are in. No way to receive someone else's guidance.

 

[gismo]

At first I thought it was an April Fool's joke. That's pretty interesting. The Watertown airport website brags that its installation is the first TLS in the country, but no info on the approach itself. Probably need to talk to the airport? Or just dial in the VOR?

No special equipment is required in the plane, you "dial in" the LOC frequency and fly it similar to an ILS. I do think you need a special transponder code but I assumed you'd get that from ATC. One downside is that only one aircraft can use the guidance at the same time and AFaIK if another airplane happens to switch to "your" code your approach could be seriously messed up.

 

[Steve]

I remember reading about this when it first came out...touted to be cheaper than an ILS installation.

Same company came up with an Automated Airport Advisory Service...

http://www.generalaviationnews.com/....lasso?-token.key=71&-token.src=news&-nothing

White paper attached.

 

[flyingcheesehead]

no info on the approach itself. Probably need to talk to the airport? Or just dial in the VOR?

What VOR? There is none on the field. Also, what are the minimums, final approach course, blah blah blah... There's no plate!

Maybe ya gotta ask one of Wisconsin Aviation's charter pilots.

magine a pilot has keyed in the wrong transponder code and is receiving guidance for another aircraft. At least with WAAS, the guidance a pilot is receiving is derived for the aircraft they are in. No way to receive someone else's guidance.

No, this is why only one aircraft can fly the approach at a time. It can only provide guidance to one, so only one can fly it. If a second aircraft were to attempt it, that'd screw it up big-time. The "disadvantage" is that it can't be used to replace the ILS's at O'Hare.

No special equipment is required in the plane, you "dial in" the LOC frequency and fly it similar to an ILS. I do think you need a special transponder code but I assumed you'd get that from ATC.

What Loc frequency? There is no localizer, no plate, no nothing.

Next time I'm out there during the day, I'll have to ask Jeff Baum how it's done.

 

[gismo]

There has to be an approach diagram with frequency and minimums somewhere, but apparently that's not published. AFaIK the system transmits on a LOC and paired GS frequency so there has to be one of those involved even though there's no actual LOC or GS ground station. The TLS works just the opposite of a "real" ILS by adjusting the LOC and GS modulation based on the airplane's position.

 

[flyingcheesehead]

There has to be an approach diagram with frequency and minimums somewhere, but apparently that's not published.

Well, I just happened to go to RYV to eat dinner at Steakfire tonight, and Jeff Baum (Pres. of Wisconsin Aviation) happened to be working late. Unfortunately, he said that the TLS was taken down about a month ago.

He said that the plate was available from Wisconsin Aviation. He also said the FAA didn't like the TLS because it wasn't their idea, and for a time actually tried to prohibit people from flying it even VFR! This particular installation was paid for by the Wisconsin Department of Aeronautics.

The other neat thing about it was that it had a curved final approach path, which you can do when the "localizer" isn't just a radio beam.

Oh well... Another good idea bites the dust.

 

[Let'sgoflying!]

something from the AIM
http://www.aopa.org/members/files/aim/chapter_1.html
c. Transponder Landing System (TLS)

1. The TLS is designed to provide approach guidance utilizing existing airborne ILS localizer, glide slope, and transponder equipment.

2. Ground equipment consists of a transponder interrogator, sensor arrays to detect lateral and vertical position, and ILS frequency transmitters. The TLS detects the aircraft's position by interrogating its transponder. It then broadcasts ILS frequency signals to guide the aircraft along the desired approach path.

3. TLS instrument approach procedures are designated Special Instrument Approach Procedures. Special aircrew training is required. TLS ground equipment provides approach guidance for only one aircraft at a time. Even though the TLS signal is received using the ILS receiver, no fixed course or glidepath is generated. The concept of operation is very similar to an air traffic controller providing radar vectors, and just as with radar vectors, the guidance is valid only for the intended aircraft. The TLS ground equipment tracks one aircraft, based on its transponder code, and provides correction signals to course and glidepath based on the position of the tracked aircraft. Flying the TLS corrections computed for another aircraft will not provide guidance relative to the approach; therefore, aircrews must not use the TLS signal for navigation unless they have received approach clearance and completed the required coordination with the TLS ground equipment operator. Navigation fixes based on conventional NAVAIDs or GPS are provided in the special instrument approach procedure to allow aircrews to verify the TLS guidance.