This week, a cancer victim made headlines for being kicked off of Alaska Airlines for not having a doctor's note.  The airline later apologized and reimbursed her and her family the money for tickets and accommodation --only after the story went viral. 

Cabin crews are increasing under pressure to police the not so friendly skies, and sometimes assessing what constitutes a security threat or what may be offensive to others isn't so clear.  But you can be sure that the airlines aren't leaving much room for debate.

If you travel quite frequently, you’ve probably seen it happen. A flight attendant points at a passenger while security personnel step in to remove them from the aircraft. Sometimes it happens before the plane is fully boarded, but more often than not it happens when the plane is getting ready to push back from the gate. 

So here are some tips for NOT getting kicked off the plane:

Don’t Joke Around

This comes down to the acronym MOTO (or Master of the Obvious). Why do some people think it’s funny to joke about bombs or weapons when going through security or boarding a plane? It happens, and those individuals are quickly removed and interrogated to see if they are a threat. Others who threaten or assault a crew member, damage the aircraft or make threatening statements are quickly removed as well. So don’t do the obvious by making threats pertaining to bombs, weapons, damaging the aircraft, charging the cockpit or assaulting a flight crew member

Don’t Swear

According to a 2011 story on Gawker, a passenger on a flight from Detroit turned to his seatmate and said: “What's taking so fucking long to close the overheard compartments?" Shortly thereafter, after the aircraft took off, the pilot turned the plane around and police removed the passenger from the plane. Why did the pilot do that? He called that passenger "disruptive." Now this may be an extreme, but if you drop the F-bomb, you may find yourself without a ride.

Don’t Wear Offensive Clothing

Airlines have what’s known as a “contract of carriage,” which is basically a contract you agree to when you purchase a seat on a plane. Most people don’t know what’s in it, and would never bother to read it. Let’s face it, there’s nothing you can do about what’s in it after the fact.

Southwest Airlines clearly states that it can “refuse to transport or remove" passengers for all kinds of violations, including those "whose clothing is lewd, obscene, or patently offensive.” Not knowing what’s in the “Contract of Carriage” doesn’t give you the right to ignore the fine print.

Last month one passenger found out the hard way when he was removed from a flight at Denver International Airport. The T-shirt he was wearing promoted a show on Comedy Central called “Broad City,” but read “Broad F%#@ing City.” The college student refused to remove the shirt, so the airline denied him passage.

Don’t Stink

That’s right. Airlines reserve the right to remove you from the plane should you emanate what is defined as an “offensive odor.” You may think you smell fine, but others around you might speak up, which will end up leaving you back at the gate. Your wife might think you smell fine, but it’s the airline that has the final say. It’s a very unusual occurrence, but it has indeed happened in the past.

The vast majority of travelers never have to worry about getting kicked off a plane, except when it’s oversold and they get bumped involuntarily. In that case, at least there’s some compensation—and an onward ticket to their final destination.

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Mark Murphy is a noted travel expert, author and founder of TravelPulse.com.  You can follow him on Twitter at @murphytravels.