At least five Aer Lingus flights will not leave Dublin Airport today because of Covid cases among staff.
Trips to Hamburg, Berlin and three to London Heathrow have been cancelled so far.
Six flights, due to depart from Dublin Airport, were also called off yesterday, while a flight to Bordeaux due to take off tomorrow has also been cancelled.
Travel writer Eoghan Corry says it's a widespread problem across the industry:
"All the airlines, all the service area, the airport itself famously with the security queue, have run into this problem.
You run through your standby staff fairly quickly, and the other issue is with delays you can also run into real issues.
Airlines are not like shops - you don't hire someone to do overtime and ask them to do an extra few hours, with pilots and cabin crew, if you're out of hours, you need a new crew"