Yep, you need to have a very strong stomach to be paxing or deadheading; some bloke was woken up from his deep slumber in the FC cabin while deadheading to JFK one day not too long ago and summoned to the cockpit. There was utter confusion in the cockpit with barely 20 to 30 mins of fuel left...........JFK, EWR and Philly were closed and crew were so ATC English challenged that they couldn't make head or tail what ATC was advising or instructing them........with such low fuel skipper said nothing. Deadheading crew was totally aghast and in no certain terms demanded the crew declare emergecy which they did after much deliberations; deadheader helped with the ' complicated ' ATC' communications and they were ' safely ' diverted to Andrews Air Force Base. WHEW!
In my previous life with them, deadheading back to LHR was always a dread when we have gales in southern Brittania!