FILE PHOTO: A Thomas Cook Airbus A330 aircraft prepares to take off from Manchester Airport in Manchester, Britain September 4, 2018. REUTERS/Phil Noble/File Photo

BERLIN (Reuters) - Air traffic could be grounded for up to a week after a disorderly exit of Britain from the European Union due to uncertainty over future air traffic rules, Christoph Debus, head of Thomas Cook Airlines TCG.L, said on Friday.

British airlines currently have unlimited flying rights to and from the EU as part of the single market’s common aviation rulebook. But it remains unclear what rules will govern flying rights after Brexit, so Thomas Cook has drawn up contingency plans, Debus said.

“We have done our homework even for the scenario of a ‘no deal’,” Debus explained.

“It cannot be ruled out that air traffic will be grounded for a day or a week,” Debus told reporters in Berlin, referring to the period immediately after the end of March 2019, when Britain formally exits.

“In a period of political instability we need to be prepared for a no-deal scenario,” he said.