Almost half of all flights in the European aviation network could face delays on Tuesday due to a technical problem that occurred at the European air traffic control operator, Eurocontrol.
Eurocontrol said in a statement that half of the expected 29,500 flights could have "some delay as a result of the system outage."
According to the statement, the problem was caused by a failure of the flow management function of the network manager, which regulates the flow of flights around Europe.
Contingency procedures are underway, it said.
Due to the technical failure, flight plans filed before 10:26 a.m. UTC were lost and aircraft operators were asked to re-file them for all aircraft that had not yet departed.
Several airports in the region, including Brussels International Airport, have warned that there might be delays because of Eurocontrol's system failure.