"Today 29,500 flights were expected in the European network. Approximately half of those could have some delay as a result of the system outage," the Eurocontrol operator said in a statement.
The Eurocontrol further added that the normal operations were expected to be resumed by late Tuesday evening.
The medium daily traffic in April in Eurocontrol's 41 member states is almost 30,000 flights, which probably means that 3,000 flights were suspended and up to half a million passengers could have lost their flights.
Yet the situation has continued without severe consequences yet.
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Earlier, Air France had to cancel 24 percent of its flights due to a strike of the company's personnel, who demand a six-percent pay increase.