NEW YORK • It is the year-end season of the squeeze. Picture thousands of stressed-out holiday travellers in airport terminals, all piling into a claustrophobia-inducing cattle-class cabin.
Is your blood pressure rising yet?
"The worst offenders are people who abuse the carry-on luggage limit and take up more space than they are supposed to get," said Mr Raymond Lee, a finance director for a consumer goods company in New York and a frequent traveller.
"They are also the ones who will put their luggage sideways and take up more space... they just do not care to do it right."
But do not take his word for it. Simply board a flight, grab a seat and watch.
Chances are, you will see a fellow passenger try to wedge a too-large carry-on into an overhead bin, a thoughtless passenger with a backpack whacking another traveller or two people bickering over the space under their seats.
Take bags off of your shoulder, especially backpacks, before walking down the plane aisle. I can't tell you how many times I've been whacked in the face by someone carrying the contents of his entire life on his shoulder, with him none the wiser.
Ms Sarah Howell, a corporate trainer and frequent business traveller.
What better time to brush up on your luggage etiquette and learn a defensive manoeuvre or two?
It starts with what you bring.
"Consumers are looking for the most possible space and lightest-weight case possible," said Mr Scott Niekelski, a manager at the National Luggage Dealers Association.
That may be the wrong impulse. When it comes to proper luggage etiquette - less is more. The most experienced passengers travel light. Some do not bring any luggage.
"I ship my gear ahead to my destination, especially if I plan to be in one place for an extended period," said Mr Brian Teeter, author of the Healthy Trekking Travel Guides series. "That way, I can travel light and have my main luggage waiting when I arrive."
But most people travel with at least a backpack, purse or some other carry-on.
On planes, carry-on luggage is a constant irritant. Airlines are partly to blame since checked luggage fees incentivise passengers to carry most of their belongings with them.
Protocol experts said the key to avoiding scraps over luggage is packing light and moving fast.
Downsize to a smaller carry-on or a backpack and place it in the bin above your seat - not someone else's.
Speed matters. Do not overstuff your bag to the point where you have to wrestle it into the compartment.
"Stow carry-on luggage quickly in the overhead bin so other passengers may pass in the aisle," said Ms Rachel Wagner, a corporate etiquette consultant.
"If you need extra time to stow it, step into the seat area for a moment so others may pass by, then step back into the aisle when there's a short break in the aisle."
No one likes a blocker and that is true at the luggage carousel as well.
Consider the mad dash for the best position. For some reason, passengers feel they own the spot immediately next to the conveyor belt and refuse to give it up for anyone, even if those people see their luggage and want to collect it.
"Don't hover around the baggage carousel," said photographer Gary Arndt, who travels constantly for work. "Stand at least several steps back from the carousel and step forward only when your bag is actually coming past."
Backpacks are another source of pain for travellers and that is true not only on planes, but also on buses, trains or any mode of transportation with narrow corridors.
The problem? During boarding and disembarking, it is easy to turn quickly and unwittingly hit fellow passengers.
"Take bags off of your shoulder, especially backpacks, before walking down the plane aisle," said Ms Sarah Howell, a corporate trainer and frequent business traveller. "I can't tell you how many times I've been whacked in the face by someone carrying the contents of his entire life on his shoulder, with him none the wiser."
Parents, if you can avoid taking a stroller, do. Strollers are clunky and are easily damaged when you gate-check them. Also monitor older kids with luggage.
"Don't let children wheel their own suitcases through the airport," said Ms Evie Granville, a writer and podcaster who deals with parenting etiquette issues at EvieandSarah.com. "Instead, pack a backpack for them to carry."
Luggage etiquette is only a partial solution to the seasonal squeeze. You have to also play defence.
Watch out for the backpacks, the passengers with the overstuffed bags, the parents with strollers and, yes, the tweens with wheeled luggage. Do not assume they have the same good manners you do and do not be surprised if you have to dodge speeding carry-ons.
Correction note: An earlier version of the article wrongly identified Ms Evie Granville's occupation. We are sorry for the error.