In late July, a traveler about to board a Southwest flight was blocked from taking his seat because of a T-shirt. The would-be passenger said he was denied a seat because of the “political” message on shirt which featured the Republican presidential nominee Donald Trump. 

Not so, said Southwest. 

It was a word on the shirt (it began with the letter “f”) that was the problem, or as an airline spokesman put it, a word “widely considered offensive.” When the passenger refused to change, or even turn the shirt inside out, things escalated and he got the boot.

So, does Southwest have a dress code you should know about? 

No, I was told. However, according to its contract of carriage – legalese for airline rules – passengers can be denied boarding if their “clothing is lewd, obscene, or patently offensive.” Who makes the call? Airline employees. There are other surprising rules that can keep you off a plane, too, and we found all of the ones below in airline contracts of carriage.

1. Not enough clothes

Almost every airline bans shirts with obscene messages, but Virgin America goes a step further on the fashion-front, telling travelers that they will not be transported if they are “not wearing both top and bottom apparel.” Hard to believe one could forget something like this but it’s happened.

2. Not enough deodorant

According to American Airlines’ contract of carriage, you will not be allowed on the plane if you “have an offensive odor.” You might be surprised to learn nearly every airline says the same thing, and yes, people have been kicked off planes for this, including a man forced off an Air Canada jet a few years back for exuding what one fellow passenger described as a “brutal” aroma.

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3. If you are really, really sick

Many of us have flown with a cold or other minor ailment but Delta points out (as do other airlines) that you might run into trouble at the gate if you are “seriously ill, and fail to provide a physician’s written permission to fly.”

Yes, this is rare, but we know of instances where it has happened including during the H1N1 flu-like virus outbreak in 2009. If you are very sick, don’t make yourself miserable by chancing a flight – not to mention risking the health of fellow passengers.

4.  If you travel with the wrong emotional support animal

Actually, you won’t be kicked off but JetBlue will deny boarding to your “unusual” emotional support pet– and if you must travel with your snake (or ferret or spider)– you won’t be along for the ride either. No reasons are given but presumably the airline is looking out for the emotional comfort of passengers who don’t wish to be seated beside a supportive spider or pooping pig.

5. If you are doing time

Spirit Airlines “will not transport prisoners in the custody of law enforcement under any circumstances with or without restraints.” Some airlines do allow uncuffed individuals but just don’t do the crime if you can’t stand a nice long bus ride.

Rick Seaney is an airline travel expert and the co-founder of, an airfare comparison shopping site