Larry Dighera schrieb:

Would that Mode S requirement be a result of the implement ion of
outsource ATC?

No, why should it? Mode S implementation is very expensive for ATC. It's
as I said: They say that in certain regions iof Europe, Mode C reaches
its limits. As I don't know anything about it, I have to believe it.

From http://www.eurocontrol.int/msa/public/faq/faq.html:
Mode S is being deployed because the current SSR systems have reached
the limit of their operational capability. This takes the form of
exceeded maximum number of targets, RF pollution, lost targets, identity
errors and Mode A code shortage. Mode S is therefore a necessary SSR
replacement in airspace subject to high levels of traffic density.

Stefan