Take 300 people, most of them strangers to one another. Jam them into limited space for 10 to 12 hours, during which they have to sit side-by-side. Thin out the air to make everyone a bit more tired and tetchy. Add some stress and fatigue.
It could be the recipe for a new reality TV program, but this show is played live over 100,000 times a day at airports around the world.
All too often it seems that travellers don't pack social graces in their carry-on luggage.
Little wonder that there's enough pent-up tension simmering among travellers to make the average Big Brother household look like a happy hippie commune.
Don't get me wrong – it's not as if hundreds of passengers are about to go postal on their seatmates.
But all too often it seems that travellers don't pack social graces in their carry-on luggage.
Is it simply that tolerance levels decrease because we're stressed, sometimes rushed, cramped, tired, hungry and bored?
Or do cheap tickets and the rise of the 'cashed-up bogan' equate to travellers who bring to the airplane the same self-centred habits and lack of civility that they'd exhibit on the ground?
(While these observations apply mainly to economy, where legroom and privacy are at a minimum, business class can have its own share of cashed-up bogans and the Don't You Know Who I Am brigade.)
Whatever the reason, the results are the same. The act of reclining your seat becomes a turf war over personal space. Subtle (and not-so-subtle) maneuvering for the armrest. iPods with the volume wound up to 11. And kids? Don't get me started on the annoying in-flight antics of kids!
Most of this is stems from personal attitude rather than altitude.
I like to think that frequent flyers are the exception. We're well-organised, we know how to travel with a minimum of fuss for ourselves and others.
Our take is that because we're all stuck together in this tin can for the next 10 hours, let's try to make it work out with a smile instead of a snarl.
It can also be said that airlines are party to this, bringing out the worst in passengers by squeezing more people onto each flight and cutting back on in-flight amenities.
Even little touches help keep things humming along. Even notice how, on a Qantas international flight, the mood in the economy cabin skyrockets when the flight attendants hand out those Weiss ice-cream bars and cups of hot chocolate?
But airlines could do more to promote flight etiquette. Maybe an announcement, following the pre-flight safety demo, suggesting that "as we'll all be together for the next eight hours, please be considerate of your fellow travellers when reclining your seat and playing music over your headphones."
Airlines could also offer some specific in-flight etiquette suggestions in an email with your itinerary or on your e-ticket.
Until that happens, here are a few starters.
Flight etiquette begins on the ground, in the airport lounge.
Using your laptop to watch a video, play some music, make a Skype call or keep Junior entertained with his or her favourite Wiggles videos – with the sound blasting through your laptop's speaker?
Let me tell you about this amazing new invention called 'headphones' which you can even use in the plane.
Bag-swingers and bag-stuffers
Passengers who hoist carry-on bags over their shoulder rather than holding it in front of them risk giving a black eye to travellers who are already seated.
And bloated hand luggage that's bursting at the seams and needs a shot-putter to wedge it into overhead bins? Give me a break. There's a reason why carry-on baggage is limited and bins are not TARDIS-like portals to infinite space.
Second bag smarts
Worse still are passengers who bounce up and down to fetch items from their carry-on bag. It's better for you and your seatmates if you bring a second, much smaller bag – one that can be stowed under the seat in front of you – with everything you'll need during the flight.
Blokes should consider a compact messenger-style satchel that can hold an iPad, noise-cancelling headphones, a small set of in-flight toiletries, your travel wallet and such.
Rules for reclining
This is the flashpoint for in-flight aggravation.
(Airlines have tried to overcome this with seats which are mounted in a fixed shell, such as Cathay Pacific's international economy seat. But they often fail in ergonomics – hence why Cathay is rolling out a new economy seat with a proper recline.)
I'm a firm believer that you don't need to ask permission to recline your seat – you paid for that right when you bought your ticket.
At the same time, you have every right to the personal space which the seat ahead of you will be reclining into.
So there's a middle ground where manners and consideration are needed.
Before you hit the recline button, check if the person behind you is using a laptop and needs to adjust their screen or extend the tray table.
You don't have to ask them if you can recline your seat, but it doesn't hurt to let them know that you're going to recline it "a bit" to get some sleep.
Then do it slowly, or even just halfway.
If you're in a two-seater, the armrest should be there to share. If your seatmate insists on hogging it then you need to either put up with it or reclaim your own slice of turf when they take a toilet break.
But where there's a middle seat, frequent flyers generally accept that the person in the middle should get both armrests because they don't have the side space of either a window or aisle to gently lean into.
What's your experience with flight etiquette and what suggestions do you have to make flying a little more enjoyable for everyone?
David Flynn is a business travel expert and editor of Australian Business Traveller.