The jerk in front of you who reclines his seat will probably claim that he has a natural, God-given right to do so. And even if that is the case, I'm still in support of the demonization and vilification of seat recliners.
I think this plane faux pas is especially audacious on super short flights. Reclining to sleep during an ten-hour flight makes sense, but treating your plane seat like a La-Z-Boy on a 90-minute flight is unforgivable.
There's nothing more terrifying than being in the throes of flying sickness while your seatmate pulls out a huge bag of pungent beef jerky. Pungent food in close quarters is just no fun for the noses involved.
The airline food might be terrible, but at least you won't have everyone in a 12-foot radius reaching for their barf bags.
Getting Motion Sickness
Airplane etiquette is not legally enforceable, but generally, the person in the aisle gets the aisle armrest, the person near the window gets the window armrest, and the person in the middle gets the two middle ones as a consolation prize for their terrible seat.
Anyone who's actually been on a plane knows that is hardly ever the case, though. Even the nicest among us are willing to shed some blood in order to secure a little more elbow room on a flight.
People Who Don't Use Headphones
People Who Clip Their Finger/Toenails
First things first--clipping anything on a flight is so far beyond the pale of what is just and good. But there's more to it than that.
Obviously there's a hierachy to clipping. If someone was clipping their fingernails next to me, I probably wouldn't say anything to their face, but I would definitely tell all the sordid details to anyone who listened to me after landing. But if you pop off a shoe and pull out some clippers, we're about to have a fist fight thousands of feet in the air.
If I ran the airlines, everyone would take a legally binding vow of silence upon entering the plane. But until that day comes, I'll just have to settle for complaining about loud talkers.
If reason doesn't work with them (and of course it won't), then I would suggest going the patronizing route--looking at them like a child and telling them to use their "library voice."
Trying to Disembark in the Wrong Order
It happens on every plane--some chump in the back row pops up and starts grabbing his things from the moment the plane's wheels touch the ground.
But the funny thing is that these kinds of people are inconveniencing themselves just as much as they are the people around them. When was the last time you saw a back rower make it successfully to the front of the plane without encountering another roadblock?
People Who Complain About Delays
People Who Fall Asleep On You
This one would almost be cute...if you didn't have a drooling, snoring stranger on your shoulder.
Most people don't intend to fall asleep on strangers and would be mortified if they did. So now, you're stuck in this situation that nobody really caused but where everyone is uncomfortable and embarrassed.
People Who Drink Too Much
You can feasibly escape an obnoxious drunk at a bar, but on a plane you have nowhere to run--which only seems to encourage their bad behavior even more.
What's worse is that alcohol hits you harder in the air than on land, so some people might not have any intention of getting totally sloshed but end up that way anyways.