Why airlines bump passengers, and what you can do about it

Welcome to one of the busiest travel times of the year. The airports are going to be absolutely packed this weekend, and bad weather could make an already hellish travel experience even worse. Add to that aircraft changes and overbooked flights, and it's pretty much assured that there will be some unhappy travelers who aren't getting home when their tickets say they will.

So what do airlines owe you when they delay or bump you, and what can you do about it? We looked into it, and here's a quick rundown of the basics of what you can expect from US carriers on domestic flights.

Here are your rights

In the case of a delay, federal law has almost nothing to say about what an airline has to do for you. At the very least, they have to be humane when it comes to tarmac delays — in most cases, an airline can't keep domestic fliers waiting on the tarmac for more than three hours, and for any delay exceeding two they have to have food and drinking water. But beyond that, it's really mostly up to airlines how they handle customers who are delayed.

FEDERAL LAW DOESN'T REALLY SAY MUCH ABOUT WHAT AIRLINES HAVE TO DO WHEN YOU'RE DELAYED

Likewise, as many travelers know all too well, airlines oversell flights all the time, to compensate for no-show passengers. But what comes next depends whether people are willing to be bumped from that flight voluntarily.

First, most airlines will make an offer for anyone willing to wait for a later flight, like a travel voucher. In that case, the transaction is between the airline and the customer — the law has nothing to do with it.

But let's say the airline can't find enough people to voluntarily exit the flight. In that case, it has to do what are called "involuntary deboards," which is what some airlines call kicking someone off a flight who doesn't want to be kicked off.

In that particular case, you may be entitled to cash — but once again, it depends. If the airline finds a way to get you to your destination within one hour of your original arrival time, they owe you nothing. If it's one to two hours (or more than two for international flights), they owe you 200 percent (or $650, whichever is smaller) of your one-way fare, and if it's more than two hours (or four, for international flights), they owe you 400 percent (up to a max of $1,300) of your fare. An airline may try to negotiate with you (or vice versa) for some sort of a voucher in this case as well, but if you want the money, you are entitled to it.

(Unfortunately, this only applies in cases of overbooking. If you get bumped because an airline has to switch out a big plane in favor of a small one, these cash perks don't apply to you.)

For a full rundown of everything you can legally expect of an air carrier in the US, from airfares to baggage handling, the Department of Transportation's consumer guide to air travel is a good place to start.

This is more or less how Dante described Purgatory. (Getty Images)

If I'm delayed, don't airlines owe me food or a hotel?

Nope. Or, at least, they're not legally required to give you one. But a lot of airlines will go above and beyond anyway. You can see airlines' policies for delays, as well as overbooking and really most of the minor details about your flight you can think of in documents called contracts of carriage. Many airlines, for example, have policies saying they will get you a hotel room for you if you are delayed overnight. But there are also differences both big and subtle in airlines' official policies.

OVERBOOKING IS INFURIATING, BUT AT THE VERY LEAST, GETTING BUMPED AGAINST YOUR WILL IS QUITE RARE.

Delta, for example, says that if it delays a person by 90 minutes or more or causes them to miss a connection, they will refund the unused portion of a ticket if a passenger requests it. American has no such policy (though it will refund a ticket for what it calls "force majeure" events, like "acts of God").

If you ever question how an airline is treating you, its contract of carriage is usually a great place to start.

Literally The Worst. (Getty Images)

Why do airlines overbook, anyway?

We mentioned above that airlines overbook to compensate for "no-shows." A lot of those are people who just miss their flights, but some airlines are inadvertently incentivizing people to ditch their flights — rising ticket-change fees sometimes mean it makes more sense to just cancel a ticket (or not show up for a flight) than to get an airline to change a ticket, as the Washington Post's Christopher Elliott wrote last year.

But for the whole year of 2013, there were 523,645 voluntary or involuntary deboards on US airlines, which totals out to only 8 per 10,000 passengers. Look at just involuntary deboards and it's only 0.92 per 10,000 passengers.

So the good news is that it's relatively rare, and there's more good news: it has gotten rarer in the last few years. But part of it is that airlines have gotten way smarter about overbooking. By using years and years of past data on no-shows, they can better guess how many people will, as Businessweek's Justin Bachman wrote earlier this year. And overbooking has improved in the last few years — it was around 30 percent more common in 2009, when nearly 1.2 per 10,000 passengers were bumped against their will.

It sounds like an insane system, and if you've ever been bumped, it's just infuriating. But counterintuitively, it more often than not works out for everyone, says Brett Snyder, who runs air travel assistance service Cranky Flier and has worked in the air travel industry for nearly two decades. Bumping people is profitable for airlines, but it works because of all the deal-hunting passengers out there.

"It is generally really good for everybody involved. [Airlines] know there will be no-shows," he says. "By selling more seats they're able to keep fares lower because otherwise they wouldn't be able to sell those extra seats at higher fares. Then for all the people that get bumped voluntarily, they get freebies."

Ready to protect the friendly skies from moisturizer. (Getty Images)

So can you avoid being bumped?

You can do a few things, but there's only so much. JetBlue is famous for not overbooking, so if you are dead set on not getting bumped, you can do what you can to fly that airline. Virgin America also limits its overbookings. In all of 2013, JetBlue only involuntarily bumped 19 people, and for Virgin America it was only 26. That puts them leaps and bounds below most other airlines.

If you don't get assigned a seat at check-in time, that's often a sign you're more likely to be bumped (but keep in mind that Southwest Airlines, for example, doesn't do assigned seats). You can also make sure you show up early, since when people check in is usually a factor in how airlines determine who gets bumped and who doesn't. But even then, being conscientious about time might not save you. Passengers in first class, business, and who paid full-fare will often be more likely to stick on the flight, regardless of check-in time. It's hard to make blanketstatements about how airlines prioritize passengers because different airlines have different policies.

Some people are (for good reason) virtually bump-proof. A United Airlines spokesman explains that unaccompanied minors, for example, are less likely to be bumped, and the airline will also try to keep families together, which can up other passengers' chances of being kicked off a flight.

COMPLAINING ON TWITTER CAN ONLY GET YOU SO FAR

Complaining on Twitter can maybe make you feel better and will definitely get many airlines' attention — big airlines have customer service representatives closely watching social media. But they can only do so much.

"The Twitter folks aren't going to be able to reorder the list to get a seat ... I would say it's most likely going to be a waste [in the case of overbooking]," says Snyder. "But if your flight's canceled or you are going to miss a connection, they can in theory help you get rebooked," he says, listing Delta and Jet Blue in particular as having helpful Twitter accounts.

If you need to get to your destination and are willing spend some extra money, you can take the advice of Alexander Anolik, a travel and tourism attorney and law professor who wrote about airline passengers' rights for the American Bar Association in 2013.

"If I absolutely need to get onto a flight that has been oversold, I will yell out (without alarming the security officers) that I will throw in an extra few hundred dollars to obtain a volunteer," he writes. That may sound silly, but in some cases (i.e. if you're an attorney who's also on the clock), the cost-benefit analysis might skew in favor of wheeling and dealing in the gate area.

"Another few hundred when you have to get to a meeting and you are billing at twice this amount or more has worked for me and for my friends who have called me from the airport asking what to do," he adds.

At the very least, one of the best things you can do is know your rights and know what an airline has promised. Often, an airline will offer you vouchers instead of cash when you've been involuntarily bumped, and Delta's refund policy only works at the request of the customer. If you don't ask, you might not get what you're entitled to.