London’s Heathrow airport aims to boost capacity even before a new runway opens, with the rejigging of the way two existing landing strips are used to add 25,000 aircraft movements a year.

The project, revealed Tuesday as part of a consultation process on the 16 billion-pound ($20 billion) third runway, may stir controversy at Europe’s busiest airport due to added disruption to local residents years before the planned infrastructure comes into use in 2026. The extra flights would represent about 5 percent more than a current cap.

A key change would allow jets to use existing runways for both landing and take offs in the same direction from 2022, breaking from an arrangement that sees one used for arrivals and the other for departures.

While that would boost punctuality, “flight paths could overfly areas that are not affected by Heathrow arrivals today,” the airport said in the study on proposed airspace changes.

Heathrow also proposes that a limit of 480,000 flights a year from the existing runways be scrapped once planning permission for the third strip is received. That would allow about 5 percent more flights, depending on terms of noise and night-flight curbs that have yet to be agreed. The third runway itself will lift annual capacity by almost 75 percent to 135 million travelers.

The London hub has been close to capacity since the start of the decade, squeezing in more passengers only because airlines are moving to bigger jets. Enlarging the airport will be crucial to the U.K. economy, especially in the wake of Brexit, the government has said.

Other proposals detail how flights could alternate from the three future runways to best manage noise and offer periods of respite. Detailed plans for the new strip and physical infrastructure will be revealed in June.