robin,
The UK is unusual in offering some level of IFR separation through ATC in its Class G airspace. Most countries, such as the US, only offer separation in Class G airspace through flight planning (that is, ATM not ATC).
Most TCAS-equipped kit will be flying most of the time in Class A or B airspace, and (in most countries) ATC is not going to be providing separation under IFR for Class G airspace, so TCAS-ATC interactions in Class G airspace would not be an issue in most countries. However, I have no experience with IFR in Class G airspace in the UK, so I can't usefully comment on that.
PBL
Last edited by PBL; 25th Sep 2007 at 05:01.
Reason: Disambiguation