More than 200,000 passengers face travel disruption today as French air traffic controllers mount the latest in a series of strikes.
The estimate came from lobby group Airlines for Europe (A4E) which said more than 200 flights would be cancelled over a 35-hour period.
Another strike last this month will hit Italy with hundreds of flights at risk of being cancelled.
A4E managing director Thomas Reynaert said: “Just last week, we released a new study on the economic impact of ATC strikes in Europe.
“The analysis revealed that between 2010-15 the overall impact of these strikes reduced European Union GDP up to €9.5 billion.
“Southern European states suffer more than others from ATC strikes because passengers are unable to reach their holiday destination.
“The EU Commission needs to put the tourism sector back into the spotlight to prevent the holidays of European families being spoilt by these strikes which cause major disruption for passengers.”
ATC strikes in Greece, Italy, Belgium and France since March have caused more than 3,500 cancellations among A4E members and more than one million minutes of delay across all airlines operating in European airspace.