Get Quartz in your inbox

Free daily briefing on global business news.

Bumped from a flight? 10 rules on volunteering, pay and complaints

Knowing what to do if your flight is overbooked matters at the gate; these 10 steps cover volunteer offers, denied boarding compensation and complaints in the U.S., EU and Canada

A confirmed airline ticket is a reservation for a seat, not a guarantee of one. Airlines sell more tickets than a plane has seats because some ticketed passengers never show up. In the U.S., that practice is legal. When more travelers arrive than the aircraft can hold, the gate agent has a seating problem. Someone has to take a later flight.

What happens next depends largely on what a passenger knows. Being bumped from a flight can mean leaving with a negotiated travel credit, a cash payment set by regulation or nothing at all. The difference can come down to choices made at check-in, at the gate and in the few minutes after an agent asks for volunteers.

The central distinction is between voluntary and involuntary bumping. A volunteer gives up a seat in exchange for whatever the airline offers. No federal rule sets that amount, which makes it a negotiation. A passenger denied boarding against their will falls under a different set of rules. In the U.S., those rules come from the Department of Transportation. They require airlines to seek volunteers first. They also spell out when involuntarily bumped travelers are owed compensation and how much.

The rules change outside the U.S. The European Union's Regulation 261/2004 ties denied boarding compensation to flight distance. Canada's Air Passenger Protection Regulations tie it to how late a passenger reaches their destination. Each system has its own exceptions, deadlines and enforcement bodies.

Knowing what to do if your flight is overbooked starts before anyone reaches the airport. Each airline's contract of carriage sets the order in which passengers are bumped. Missing a check-in or gate deadline can remove a traveler's right to compensation entirely.

The 10 slides that follow are a selection of practical steps and rights, not an exhaustive guide. They explain why overbooking happens and how to lower the odds of being bumped. They walk through the volunteer request, the questions to ask before accepting a deal, how U.S. compensation is calculated and when it doesn't apply. They also cover how passengers in the EU and Canada are protected. The final slide explains where to file a complaint when an airline's response comes up short.

Why airlines overbook flights and what happens when they do

Airlines sell more tickets than a flight has seats because they expect some ticketed passengers to miss it. Overbooking is legal in the U.S. When too many travelers show up, the airline moves some of them to later flights.

The logic comes down to how an airline seat works as a product. Once the cabin door closes, an empty seat on that departure can never be sold. A hotel room for a given night has the same problem. Each flight is a one-time sale, and any seat that leaves empty earns nothing.

No-shows happen for ordinary reasons. A traveler misses a connection on an earlier flight. A meeting is canceled. Someone gets sick, sits in traffic or changes plans. Some fares, especially fully refundable tickets, let a passenger skip a flight and still recover the money or move to another departure. That flexibility leaves the airline holding seats it cannot count on.

Overbooking is the airline's attempt to fill those seats in advance. Carriers estimate how many passengers are likely to miss a given flight, drawing on past booking patterns for that route and time of travel. They then sell extra tickets to cover the expected gap. The estimate is a forecast, not a guarantee.

The problem surfaces when the forecast is wrong and nearly everyone turns up. At that point the flight is oversold, with more ticketed passengers at the gate than seats on board. U.S. regulations refer to this as denied boarding. Travelers $TRV -0.09% more often call it getting bumped.

Being bumped does not mean losing the trip. The affected passenger is placed on a later flight, and the circumstances of that move determine what the passenger receives. A traveler who gives up a seat by choice is treated differently from one removed against their wishes. That split between voluntary and involuntary bumping shapes what a passenger can claim, from rebooking terms to cash compensation.

Check in early to lower your odds of getting bumped

Checking in as soon as your airline allows and reaching the gate on time are two steps that help protect your seat on an oversold flight. Both also keep you eligible for denied boarding compensation if you are bumped anyway.

The order in which passengers get bumped is not random. Each airline writes its own boarding priority rules into its contract of carriage, the legal agreement that sets the terms of a ticket. Those rules decide who loses a seat first when a flight has more passengers than seats.

The factors airlines weigh vary, but a few show up often. The fare a passenger paid is one. Frequent-flyer status is another. The time a passenger checked in is a third, and it is the one a traveler can most easily influence on the day of the trip.

At airlines where check-in time counts toward priority, a passenger who checks in the moment the window opens ranks ahead of later arrivals on that factor. Online and app check-in let travelers do this before they leave home. Fare and status can still outweigh check-in time, depending on how the carrier orders its rules.

Timing matters for a second reason. Airlines set a check-in deadline and a deadline for reaching the gate. Missing either one carries consequences. A passenger who misses the check-in deadline falls outside the compensation rules. The same applies to a passenger who reaches the gate after the airline's cutoff. A traveler in that position can........

© Quartz