Ironically, most people are not familiar with the proper etiquette and protocol when riding on commercial airliners.
The one thing that annoys me the most are people who hog the armrest (for those of you who've read my post about the First Class Terminal in Frankfurt, I wanted to clarify I was a guest of another First Class passenger and I was sitting in Coach where I usually spend my flights); theoretically, you get the right armrest to be all yours. I always try to get an aisle seat, but sometimes even then the passenger sitting next to me takes both of his armrests.
Passengers talking loudly or rudely is also very inconvenient, but what troubles me most are passengers who can't sit still. Imagine your neighbor's leg bouncing up and down like a vibrating pogo stick continuously, I don't normally try to micro-manage but this makes me question their upbringing as my parents taught me to sit still at a very young age and not to talk loudly.
When I fly, I usually fly overseas, so I would have to suffer over ten hours of an unpleasant neighbor
Have a safe flight ATM! And the noise-cancelling headphones luc00 recommended are a sound investment for anyone who flies often. This message has been edited by patrick_y on 2009-03-18 15:00:56