The government has said it wants Heathrow, located west of London and which is Europe’s busiest airport, to build a new runway in what would be a major expansion, but that is not expected to be ready until 2035 at the earliest.

In its 2027-2031 plans presented to the Civil Aviation Authority on Friday, Heathrow said it could expand before the new runway is built by upgrading facilities to add passengers. An extra 10 million passengers per year would be a 12% increase on current numbers.

The airport said the expansion plan would require the fees it charges airlines to rise to 33.26 pounds ($45.07) per passenger, up from the average charge of 28.46 pounds per passenger in the current regulatory period.

Airlines have long complained that Heathrow is one of the most expensive airports in the world and have called on the regulator to reduce the fees.

The CAA, which regulates airport charges, will study the plan before making a response.