If that's deemed inadequate for your needs and the plane is full, the airlines say you'll have to wait for another plane -- one that has an extra seat for you. The prevailing wisdom is, you know if you're "of size" or not. As Midwest Airlines carefully explains, by booking a second seat, the "customer can avoid any discussion at the gate with employees…" In other words, you don't have to risk being told you're too fat.
Ugly. But, neither is it pretty to expect airline reps and/or flight attendants to be arbiters of "size" or anything else. Remember when a young woman named Kyla Ebbert was nearly kicked off a Southwest flight for wearing -- gasp -- a mini-skirt? For those who enjoy those "Where are They Now?" features, Ms. Ebbert later parlayed her "fame" into a shoot for Playboy.
Moreover -- let's say you, a portly passenger, decides to purchase two seats -- but you discover you can't do this online -- so, you call to make your reservation. Wait a minute, do you then get hit with the phone call booking fee? The sites I've looked at do not address this very clearly.
Maybe buying two seats together online represents a technology issue. But maybe it's something else: maybe regular-sized folks will pose as members of the "big and tall" club in order to get two seats together. In other words, in order to get the comfort and room of a business or first class seat at a fraction of the price. I can hear the phone conversation with the customer service rep now: "Are you really fat, sir? You're not faking it, are you?"
You can see what a weighty can of worms this is.
By the way, I'm not saying I'm against these rules, but the airlines might want to be a little clearer about them so customers aren't blindsided. Yes, we now know all about United's regulations but who would guess that Midwest Airline's "Passenger Comfort Policy" or Air France's Web site section titled, "High Body Mass" both address obesity? A little transparency, please.
And, let's face it, passengers who shoehorn their way into seats can pose a safety problem. As Southwest spokesperson Brandy King reminds us, in an emergency, there's not a lot of time: "If the aircraft needs to be evacuated and a customer has forced the armrest down, it's going to take longer to make a quick exit."
You can't argue about saving lives. But you can argue about all the other little indignities we air travelers face these days from issues of "size" to a complete and utter lack of respect for personal space.
This work is the opinion of the columnist and in no way reflects the opinion of ABC News.
Rick Seaney is one of the country's leading experts on airfare, giving interviews and analysis to news organizations, including ABC News, The New York Times, The Wall Street Journal, Reuters, The Associated Press and Bloomberg. His Web site FareCompare.com offers consumers free, new-generation software, combined with expert insider tips to find the best airline ticket deal.