Why an airline will sell you a ticket even if the plane is full

Imagine a situation: you buy a ticket, arrive at the airport, but are told at the gate that you can’t get on the plane because all the seats are taken. How is this possible? The answer is a phenomenon called overbooking – a practice that airlines around the world have been using for decades.

Why airlines are selling more tickets than they have seats

Every flight is an expensive operation. If even a few seats remain empty, the airline loses thousands of euros. At the same time, however, not all passengers who buy a ticket actually turn up for the flight – it is called a no-show. The reasons for this are varied: delays, rescheduling, unused cheap tickets. Airlines therefore take detailed statistics – data models – and evaluate them, and on the basis of them they can sell slightly more tickets than the capacity of the aircraft. If the estimates are correct, the load factor is close to 100% and the airline earns more.

History and regulation

Overbooking emerged as early as the mid-20th century, especially in the USA. It was common in the 1970s and 1980s, but brought many complaints. That is why the authorities introduced rules to protect passengers.

USA: The Department of Transportation (DOT) has established obligations for airlines, including financial compensation.
EU: EC Regulation 261/2004 gives passengers the right to compensation of up to €600 when denied boarding due to overbooking.

Today, the practice is regulated and passengers are in a strong position.

Interesting facts from around the world

United Airlines 2017 – An incident in which a passenger was forcibly removed from a plane due to overcrowding sparked a global debate.
Delta Air Lines 2019 – proved that good management works. They had 0 forced denials per million passengers that year because they always found volunteers to have the flight rebooked or switched.

Data and facts

USA 2015-2020: the number of forced refusals dropped from 7 to 0.3 per 10 000 passengers.
EU: According to the European Commission, the number of compensation claims is around 1-2 cases per 1 000 flights.

How they can earn “twice in one seat”

If a passenger pays for a ticket but doesn’t show up, the airline keeps the money. The seat will be taken by another passenger who bought the ticket under overbooking. The result: 2 times the price paid for one seat, but only one person uses it.

How airlines calculate optimal overbooking

There are several methods:

Fixed % – sales +3 to +5 % above capacity.
Probabilistic models – calculation based on history and actual data.
Dynamic models – percentage varies by time and bookings.
Segmented models – different behaviour of leisure and business travellers.

Numerical example: the Airbus A320

Imagine a plane with 180 seats, an average ticket price of €150 and an average no-show of 3%.

0 % overbooking → sales 27 000 €
5% overbooking, compensation 250 € → sales 27 517 € (more than without overbooking)
10% overbooking, compensation 500 € → sales only 23 670 € (loss compared to current sales)

The result? Overbooking is only worthwhile when the airline estimates the no-show well and compensation costs are under control.

Compensation for overbooking in Slovakia is determined by EU Regulation 261/2004 because Slovakia is an EU member country.

What you are entitled to:

Financial compensation – depends on the length of the flight:

Flight distance	Compensation
≤ 1 500 km	€250
> 1 500 km and ≤ 3 500 km	€400
> 3 500 km	€600

Options you can choose:

refund of the ticket price (if you decide not to board the alternative flight)
rerouting/replacement flight as soon as possible or at another date that suits you, if seats are available

Compensation may be reduced (by 50%) if the airline provides you with an alternative flight and you arrive at your destination with a delay compared to the original plan, up to:

2 hours for flights ≤ 1 500 km
3 hours for flights > 1 500 km ≤ 3 500 km
4 hours for flights over 3 500 km

Overbooking is a common practice that helps airlines keep ticket prices lower and planes full. Although it can sometimes cause inconvenience, passengers are well protected in both the EU and the US. Thanks to statistics and modern algorithms, the likelihood of encountering a rejection is now minimal.

Still, overbooking is an unpleasant situation that can catch even experienced travellers by surprise. However, European rules provide clear protection and guarantee financial compensation, a replacement flight or refund of the ticket price, as well as care during the wait.

At Poprad-Tatry Airport, we recommend that passengers always keep their boarding pass and document the circumstances of the flight – this will make it much easier to make any claims. We strive to make every flight as comfortable as possible for our passengers and to prevent overbooking incidents. If they do occur, we are ready to help you with information and assistance to ensure your journey continues without undue stress.