Around half of the flights in Europe on Tuesday face delays after a computer failure at the Eurocontrol center in Brussels, Belgium.
In a press release Tuesday, the aviation body said there had been a failure of the "Enhanced Tactical Flow Management System" and all the flight plans of journeys filed before 10.26 a.m. UTC had been lost.
The system creates a flightpath for all journeys after airlines file flight plans.
The statement said many thousands of flights would be affected.
"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," it said.
The statement added that while the problem had been identified and action was underway, a contingency plan would remain in place. Eurocontrol said the backup plan would reduce the capacity of the European flight network by approximately 10 percent.
The intergovernmental organization claimed that there are no safety implications arising from the system failure.