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/1...essibility.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