(Bloomberg) -- Britain will compel airlines to use a greater proportion of takeoff and landing slots this summer, while making it easier for them opt out of flights when circumstances change.

Carriers will be required to utilize 70% of airport slots or risk losing the rights, the Department for Transport said in a statement Monday. That’s below the pre-pandemic threshold of 80% but higher than required since the virus hit.

At the same time, a list of situations in which airlines can avoid using slots, such as Covid-related border curbs, will be extended and they’ll no longer be required to show that the situation was unforeseeable. That should prevent so-called ghost flights, operated empty simply to safeguard slots, the DfT said.

Seasonal slot waivers have emerged as flashpoints in the aviation industry, with airlines seeking to hang on to flying rights even as airports push to allow in new entrants. The British switch means that carriers at hubs like London Heathrow and Gatwick will have a higher slot-usage requirement than the 64% specified by the European Union, though the bloc also has get-out clauses.

“The government’s sensible decision to return discipline to the U.K.’s airport slot regulations for the summer season is very welcome and means consumers will once again benefit from a competitive aviation market, a wider choice of services and a range of airfares to suit different needs,” Stewart Wingate, the chief executive officer of Gatwick airport, said in a statement.

U.K. slot waivers were extended last summer. The requirement was upped to 50% this winter, but only after airlines were permitted to temporarily return any slots and still retain the right to pick them up the following year.

Even as the omicron variant of Covid-19 disrupts travel, airlines including discounters Ryanair Holdings Plc and Wizz Air Holdings Plc have been pushing authorities to revert to established slot rules, maintaining that it’s in the public interest to allow the strongest players to add flights.

While airports including London Gatwick have backed that stance, network carriers take a different view, arguing that they can’t be expected to bring back flights with corporate travel still in the doldrums, and that surrendering slots now would damage connectivity and business links in the future.

Deutsche Lufthansa AG said this month that it was being forced to fly planes with below break-even passenger loads just to hang on to crucial slots, causing unnecessary carbon-dioxide emissions. The EU said airlines could apply for an exemption if unable to operate a particular route.

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