Heathrow was among several European airports hit by delays on Saturday after a cyber-attack affecting an electronic check-in and baggage system.
The airport said a number of flights were delayed as a technical issue impacted software provided to several airlines.
Brussels Airport reported reliance on manual check-ins due to the attack, while Berlin's Brandenburg Airport experienced longer waiting times.
RTX, owner of software provider Collins Aerospace, acknowledged the cyber-related disruption at select airports and confirmed efforts were underway to resolve the issue.
The impact appeared limited to electronic operations, allowing for continued manual processing, and ideally ensuring operations could recover swiftly.
Heathrow stated that, while facing challenges, the majority of flights continued operating as normal. Speculation regarding the cyber-attack's origin remains uncertain, with authorities monitoring the situation closely.
With long queues reported, passengers voiced frustrations over delays and uncertainty, underlining the significant operational disruptions the attack caused across several airports.
Transport Secretary Heidi Alexander has been receiving updates and overseeing responses to the situation, focusing on ensuring minimal disruption for passengers.
