Airports in Northern Ireland were also impacted by the worldwide IT outage on Friday.
Queues of passengers were seen at airport terminals as staff tried to deal with the travel chaos caused by the technical problems.
Both Belfast International and Belfast City airports said operations continued, but warned travellers to check with their airlines for updates.
At Belfast International Airport, staff used whiteboards to provide customers with information as some flight information screens were left frozen by the technical fault.
Passenger Martin McElroy told Sky News it was like “the dark ages, but to be fair, they’re making it work, which you have to give them credit for”.
In a statement on Friday afternoon, the airport said: “The airport remains operational with airport systems up and running and passengers being processed as normal.
“Passengers should, however, continue to check with their airline for the latest updates on their flights as delays can be expected.”
Ryanair, which flies out from Belfast International, had advised passengers it was “currently experiencing disruption across the network due to a global third party IT outage which is out of our control”.
It said it had been forced to cancel a small number of flights and there has been disruption to vehicle testing services in the Republic.
The airline also advised its passengers to arrive three hours before flights.
The Airport remains operational with airport systems up and running and passengers being processed as normal. Passengers should, however, continue to check with their airline for the latest updates on their flights as delays can be expected.
— Belfast International Airport (@belfastairport) July 19, 2024
Belfast City Airport also said although flight operations had not been “directly affected” but there was “disruption across global networks”.
Whilst flight operations from Belfast City Airport have not been directly affected by today’s global IT outages, there will be disruption across networks and passengers are therefore advised to check the status of their flights.
— Belfast City Airport (@BELFASTCITY_AIR) July 19, 2024
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Dublin Airport said that its systems are operating normally but that it had deployed additional staff in the terminals to help airlines and passengers.
