On Sep 12, 2:45*pm, Mark Dickson wrote:
As of 2012 it will be mode S, so not much point in buying anything else.

At 21:06 12 September 2009, Chris Nicholas wrote:



=93 . . . in the UK. *A transponder mandatory zone means a mode S
transponder mandatory zone. =93

Wrong, at least for the new Stansted TMZ=92s:

=93 . . . access is permitted to any aircraft which is operating a fully
functioning pressure altitude reporting transponder in accordance with
the CAA=92s TMZ Policy Statement or to those aircraft which the aircraft
commander has obtained permission from the air traffic control unit at
Stansted Airport, Farnborough Radar, or Essex Radar, as may be
appropriate, to enter the restricted airspace.=94

So it needs Mode C, not necessarily Mode S, thought the latter also
incorporates mode C.

However, for new installations, I believe that Surfer is right =96 new
installations have to mode S.

If not so, no doubt somebody else will be along soon, To clarify.

Chris N.

And for USA readers we have much longer to worry about Mode-S type
things, so normally I would have said just install a Mode-C, save some
money and in a decade replace it with Mode-S or whatever. However the
Trig TT-21 is a game changer. You get Mode S/1090ES ADS-B out
capabilities for future possible use and more immediately, it is more
compact, easier to install and uses less power than other options.

So for those folks flying in those high density/fast jet traffic areas
like near Reno, there is even less excuses not to be using a
transponder.

It will be interesting to see how Becker and others respond. Becker's
new more compact VHF radio looks really nice.

Darryl