Ryanair has renewed its call for urgent reform to Europe’s air traffic control (ATC) systems as strikes by French ATC staff extend into a fourth consecutive day. The budget airline says more than 400 of its flights have been cancelled this week, which has affected over 70,000 passengers during the height of the summer travel season.

Further disruption to flight schedules is possible today due to another day of Air Traffic Control strikes in France and also in Finland.

Ryanair said on Thursday it was forced to cancel 170 flights, disrupting travel for more than 30,000 passengers, due to a nationwide air traffic controller strike in France planned for later in the day and Friday.