A five-day French air traffic control strike has already triggered more than 830 flight cancellations over the first two days and, separately, Finnair has warned of considerable disruption March 10.

Lobby group Airlines for Europe (A4E) said more than 400 flights were canceled March 6, followed by a further 430 flights on March 7 as a result of French air traffic strikes at the Brest, Bordeaux and Marseille control centers.

In addition, A4E said there had been severe delays and detours, with the worst effects being felt in Ireland, Italy, France, Germany, Spain and the UK.

The walkout, which started March 6, will run until March 10. Since 2010, A4E estimates ATC strikes have cost the European Union economy around €12 billion ($12.7 billion).

Separately, Finnair warned that a four-hour strike on March 10 at Helsinki Airport is likely to disrupt critical ground services—such as catering and baggage handling—for more than 90 of its scheduled flights.

“Finnair is not a party to the dispute, but the impacts will cause great trouble and worry to our customers. Additionally, they will create a negative financial impact of millions of euros for us,” Finnair CFO Jaakko Schildt said.

The labor dispute, which also caused disruption March 5-6, is between the Finnish Aviation Union (IAU) and the service sector employer union, Palta.