Thanks for the interesting replies, I thought that alternates would be a real problem, especially on the southbound leg.
That brings up another question, in the past where have aircraft diverted to that couldn't get into MPA ?
Do the Argentine's allow a diversion into their territory under any circumstances ?
I imagine that otherwise Chile would be the best option ?
Interesting that non stops to the UK have been made, it sounds like northbound exclusively. I can see how the 747SP would work well for that.