Then it does get synched (confused- moi?).
Depends on what you mean by that. If they make the announcement at 10.00AM in Florida that would effectively be 4.00PM London time, or 5.00AM in New Zealand (but the following day, if I'm getting my time zones correct).
So, basically it just occurs at a given time. They will not be making repeated announcements on the hour every hour for each time zone.





