Low-fare airline easyJet is to introduce paid-for allocated seating for all flights.
Passengers will have the option to choose from three brands of pricing - £3, £8 or £12 - depending on where they want to sit.
Anyone who chooses not to pay to select their seat will be given their seat number when they check in, either online or at the airport.
EasyJet trialled allocated seating during the summer season to stress-test the new systems and procedures.
The budget carrier said on Wednesday it would roll out allocated seating during the winter season when fewer people travel to ensure a smooth transition from one system to another.
It added that the trial showed that allocated seating could be delivered "at the same time as maintaining strong levels of on-time performance and without adding cost".