Delays and flight cancellations were set to impact swathes of Europe on Thursday, after authorities failed to reach a deal with some French air traffic control workers to avert a strike.

France’s DGAC civil aviation authority said on Wednesday it had asked airlines to cancel 75% of Thursday’s flights at Paris Orly airport, 55% of flights at Paris Charles-De-Gaulle and 65% of flights at Marseille.

Air traffic control strikes in France frequently impact travel in Europe, limiting not only flights into France but also across the country’s airspace.