Reservation overbooking

Involuntary boarding denial
Airline bumping
Airlines overbook passengers by 15 to 30%. As a consequence, it has been estimated that the number of airline passengers bumped annually in North America and Europe varies from 5 to 10 per 10,000, rising to 15 for some carriers. In the case of London Heathrow, on average there are 50 to 80 passengers bumped daily by the 70 airlines operating there.
Bumping is practised by airlines in order to favour high-yield, long-haul connecting passengers, regular customers and groups.
In any specific year, 21 European airlines lost one million seats through no-shows, representing a loss of revenue of $200 million, namely 1.5% of passenger volume. Overbooking compensates for this loss and means that airlines are able to offer more seats on each flight.
(E) Emanations of other problems