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?