Germany’s largest air carrier Lufthansa made concessions to the UFO flight attendants' union after the biggest strike in the company’s history lead to the cancellation of over 1,000 flights on Friday, The Wall Street Journal reported.

The sides agreed to resume negotiations. The air carrier will also offer permanent employment contracts to its temporary staff.

DPA quoted the chief of the UFO labor union, Nicoley Baublies, as saying that no more breaks in service were planned because strikes during mediation are illegal under German labor law.

Friday’s strike, the third this week, was held at the country’s major airports in Frankfurt, Berlin, Hamburg, Munich, Dusseldorf and Stuttgart. Nearly 1,200 flights were grounded.

On Tuesday Lufthansa had to cancel some 300 flights due to striking flight attendants. The strike lasted eight hours and paralyzed three airports.

The first strike, which took place on August 31, saw about 100 flights grounded.