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Why Do Airlines Overbook Flights? (And What Can You Do About It?)

Having worked for several international airlines, I have an insider perspective on many of the seemingly mysterious sides of the industry.


As a seasoned traveller, you have likely come across the term "overbooking." The truth is, overbooking happens more often than you realise—in fact, it's a very common practice within the airline industry. Occasionally overbooking does not end nicely and leads to some passengers being denied boarding.

Why Does Overbooking Happen?

The first question most people have is why overbooking happens in the first place. It is a phenomenon unique to the airline industry; you rarely hear about other industries "overselling" their products. So, why do airlines overbook their flights?

In short, because they want to maximise their revenue.

Airlines want to maximise their revenue by filling up their flights as much as possible, ideally to 100% capacity. To do that, they need to overbook their flights before the flight departure date well beyond 100% and expect the booking level will drop and land nicely at 100% of the flight capacity.

What? The Booking Level Drops?

Yes, and that is a fundamental reason why airlines overbook. There are several reasons for the booking level to drop.

  • Ticket Change: Airline bookings are usually made well in advance, and some travellers are bound to change their plans (especially business travellers, whose plan is never really confirmed until they actually get on their flight!). Depending on the ticket types they buy, some of these ticket changes are even free of charge. Some of these ticket changes may happen very close to the departure date, meaning airlines have already lost the opportunity to sell the empty seat.
  • No-Show: Some travellers just do not turn up for their flights. Maybe they made a very last-minute change in plan (otherwise they would have changed the ticket itinerary) or they are just late. In some cases, tickets allow passengers to still change their itinerary after the no-show after paying a small no-show penalty. In this case, the airline would not be able to earn the airfare on that empty seat.

Therefore, overbooking is a technique airlines use to keep their flights full even when ticket changes or no-shows happen. This allows them to earn more revenue from their flights.

But What If Everyone Does Turn Up in the End?

Well...that's when passengers will notice something and feel the pain. If there are 302 passengers for 300 seats, something has to happen with those extra two passengers.

Sometimes overbooking can lead to upgrades (or downgrades).

Sometimes overbooking can lead to upgrades (or downgrades).

How Do Airlines Manage Overbooking?

If everyone turns up for their flight and there are simply not enough seats, the airline needs to do something about it. To begin with, airlines will usually try the following so as not to upset anyone.

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Upgrading or Downgrading

Very often, overbooking happens only in a particular cabin because the demand for one cabin is stronger than the others (e.g., economy vs. business class). This happens often during the holiday season when leisure traffic (primarily economy-class demand) is at its peak.

In these cases, flights sometimes still have seats available in other cabins. This can result in two scenarios: upgrade or downgrade. In fact, overbooking is one of the most common reasons for a free upgrade (See my other article: Quick Guide to Free Upgrades at the Airport). But in some cases, passengers may also be downgraded, with some compensation, of course.

Offering an Alternative Flight

If there is an earlier flight available, the counter staff will proactively ask everyone at check-in whether they are willing to take the earlier flight. After all, passengers who arrive at the airport early are often more than happy to avoid waiting and arrive at their destination early. If enough passengers choose to take the alternative flight, problem solved!

Looking for Volunteers

If there are no alternatives, airlines begin looking for passengers who are willing to be offloaded during check-in in exchange for decent compensation—usually cash plus a goodwill gesture from the airline such as an upgrade on the next flight, and of course a "protection" flight which still takes the passengers to their destination, but perhaps on a later flight or with another airline.

At this stage, there may be some passengers who put their hands up and volunteer to be offloaded. Depending on the airline, the compensation package differs.

Denying Boarding

But if none of the above options frees up enough seats to cater to everyone, the last resort is to deny boarding to some passengers—usually the last passengers to show up at check-in. In some cases, if the last passengers include gold-card frequent-flyer members, the airlines may reserve seats for them and deny boarding to those without any status instead.

If overbooking ends up getting you an upgrade, the ordeal may be worth it!

If overbooking ends up getting you an upgrade, the ordeal may be worth it!

What to Do If Your Flight Is Overbooked

Here are a couple of tips that may help prevent you from being denied boarding when a flight is overbooked (or help you get the most out of it if you do).

How to Prevent Being Denied Boarding

  • Check In Online: Checking in early will reduce your chance of being denied boarding. Online check-in usually opens 24–48 hours before departure, so take advantage of that option. Plus, you can often pick your seats ahead of those checking in at the airport counter.

What to Do If You Are Denied Boarding

  • Know Your Rights: If you are denied boarding, it is your right to ask for compensation and a reasonable alternative flight option to get you to your destination. If you are flying out of the EU or on a European airline, familiarise yourself with the EU261 and know what you are entitled to.
  • Be Polite: Screaming and shouting at staff won't help your cause. By the time the decision is made, it is usually final. If you are in a desperate situation, let the airline staff know your circumstances and see what they can do. I have seen compassionate travellers give up their seats to people who need to travel for serious reasons.

Otherwise, good luck!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2021 KC Chung

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