Flight operations at some of Europe’s busiest airports, including London’s Heathrow, Brussels, and Berlin Brandenburg, were thrown into disarray over the weekend following a cyberattack on a key airline software system.

The disruption, traced to Collins Aerospace’s MUSE check-in and boarding platform, forced airlines to revert to manual processes for passenger check-in, baggage drop, and boarding. The attack caused widespread delays, cancellations, and long queues as airports scrambled to maintain services.

Brussels Airport was among the hardest hit, with 50 departures cancelled on Sunday and airlines instructed to scrap nearly half of Monday’s scheduled flights. Heathrow also reported significant delays and some cancellations, though most flights managed to operate with manual workarounds. Berlin Brandenburg and Dublin airports confirmed moderate disruptions, while other hubs across the continent also reported knock-on effects.

Authorities and airline officials said efforts are underway to restore normal operations, but warned passengers to expect continued delays until Collins Aerospace delivers a secure software update.

The incident underscores the vulnerability of critical aviation infrastructure to cyber threats, with experts warning that reliance on centralized systems creates risks of cascading failures across multiple airports.

Airlines have advised passengers to check flight statuses before travelling, use online check-in where available, and arrive early at airports to minimize disruptions.