Lumps of metal filled with fat bums and bad food are not meant to fly. Gravity was invented to prevent this sort of thing from happening. I know if they keep moving forward the Laws of Physics will keep them up there but what if we got something wrong? Just what if Bernoulli was a bit off with his calculations? What if the engineer misread his slide rule? What if carbon fibre decided it just wanted to behave like the plastic handle on my spatula and break off unexpectedly? I try not to think about these things too much, especially when I am one of the fat bums eating the abominable food served by smiling stewards, all with their fingers crossed behind their back as if they know something I don't. Nevertheless, I am thankful they do fly if only to stand with my feet firmly planted on the ground and observe such a beautiful sight.