Air travellers are facing another day of disruption at several European airports including Heathrow, after a cyber-attack knocked out a check-in and baggage system.
There were hundreds of delays on Saturday after the software used by several airlines failed, with affected airports boarding passengers using pen and paper.
Brussels Airport said it had "no indication yet" when the system would be functional again and had asked airlines to cancel half their departing flights.
RTX, which owns software provider Collins Aerospace, said it was "aware of a cyber-related disruption" to its system in "select airports" and that it hoped to resolve the issue as quickly as possible.
It identified its Muse software - which allows different airlines to use the same check-in desks and boarding gates at an airport, rather than requiring their own - as the system that had been affected.
