A few years ago I was in central India talking to a recently retired American Airlines pilot at the bar who had flown out from UK with AI on a 747. His comment was when he was a pilot they often used to line up behind AI 747 and watched them struggle off down the runway at LHR go "over the hump" as he described it, slightly disappear from view and the seemingly struggle skyward. He said it was always worth watching from outside, but vouched safe that it was not so much fun when on board !