Derek Copeland wrote:

From a glider pilot's point of view, buying and fitting
this equipment is expensive - about £3000 (more than
many older and vintage gliders cost in total) , requires
a licence and regular skilled maintenance, will probably
require an extra dedicated battery to be fitted which
has to come out of our MAUW, and exposes us to fairly
continual 20 watt radio emissions that most glider
structures will not shield us from.

While you have much to fear from this proposal, 20 watts isn't one of
them. The current mode C transponder transmits between 0 and about 3
watts average power, depending on the interogation rate (peak power is
much higher, but very short duration). Mode S transmits even less power
on average, because it doesn't respond to every interrogation it receives.

The justifications for this from the CAA include allowing
Airliners to detect us as they take short cuts through
Class G airspace to save fuel and make bigger profits
for their companies(although there is no suitable currently
available equipment beyond the Mark 1 eyeball for us
to detect them or any other aircraft),

There are several transponder signal detectors on the market that will
allow you to detect airliner and general aviation transponders. They
vary in their ability to give you range and direction, and the cost
varies from ~$300US to ~$800US. Some glider pilots already use these.
What isn't clear to me is how useful they are if all transponders are
Mode S. I expect it to be the same as with the mode C transponders, but
I haven't read anything on the subject.
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Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"