Originally Posted by
DeathSlam
Just to be a completist. I think it *is* possible but a massive PITA. You will need to clear security in T5 T3 and T5 again in time to make your 'ready to fly'. Happy to be told otherwise if this is rubbish.
No, it's not rubbish, though my phrasing was perhaps slightly different to yours. The thing you left out is that your Ready to Fly would be corrupted on return to T5 and you risk losing your seat in trying to resolve it. If you tried this with less than an hour to go then the Flight Management would also need to get involved.