Heathrow is among several European airports hit by a cyber-attack affecting an electronic check-in and baggage system.
The airport warned of possible delays due to a technical issue affecting software provided by Collins Aerospace to several airlines.
Brussels Airport reported that a cyber-attack on Friday night led to manual check-in and boarding, while Berlin's Brandenburg Airport experienced longer waiting times as a result.
RTX, which owns Collins Aerospace, acknowledged a cyber-related disruption to its system in select airports and is working swiftly to resolve the issue.
The affected software, Muse, allows multiple airlines to share check-in desks and gates at an airport. British Airways reportedly continues operations normally using a backup system, but other airlines at Heathrow have been impacted.
Flight tracker FlightAware indicates that hundreds of flights have been delayed Saturday.
Passengers have expressed frustration at the long wait times, with some queuing more than two hours just to check in, while others faced complications with boarding passes.
Lucy Spencer reported difficulty checking in with Malaysia Airlines, noting, They told us to use the boarding passes on our phone, but when we got to the gates they weren't working.\
Similarly, Monazza Aslam shared her plight of being stuck on the tarmac for over an hour, missing connections due to the disruptions.
Despite the chaos, some passengers like Luke Agger-Joynes noticed that the situation was more manageable than expected in certain areas, with airport staff actively assisting travelers.
Heathrow officials have deployed additional staff to assist and recommend travelers check flight statuses before arriving at the airport.
UK Transport Secretary Heidi Alexander is closely monitoring the situation, ensuring updates as the situation unfolds.
Meanwhile, EasyJet and Ryanair, while not operating out of Heathrow, are reportedly functioning as normal.
The impact of the cyber-attack has not only hindered London but also affected flight schedules at Brussels Airport, with cancellations and delays underway.
Eurocontrol has mandated airline operators to cancel half their flight schedules for selected hours this weekend due to the ongoing disruptions.
Dublin Airport has also experienced operational impacts, with an evacuation precaution taken in its Terminal 2 without disclosure on the cause.
Experts have pointed out the intricate nature of aviation operations, warning about the potential for broader disruptions stemming from the ongoing issues.
While speculation suggests possible state-sponsored attacks, recent history indicates that many cyber incidents are frequently linked to criminal organizations exploiting vulnerabilities for financial gain.
Collins Aerospace has not yet clarified the attack's nature or its origins, leaving the situation open for further scrutiny.
