The FAA doesn't care about 'factoring', generally because the FAA regulated airlines don't use this procedure (and pilots are allowed longer annual pilot operating hours), however...if a GCAA registered airplane has an accident in the USA, the NTSB (who most certainly will have the say so) will look at the pilots rest/duty periods, at that specific time.
IE: it ain't over until the unfortunate happens.
So...keep awake guys and don't have an accident here in the USA.
