Irish airlines and airports have issued emergency contact numbers for passengers facing delays and cancellations due to the British anti-terrorism operation.
Intending Aer Lingus passengers should call 0818 365044, while Ryanair can be contacted on 0818 303030.
Passengers flying out of Cork or meeting arrivals are being urged to telephone 021 4313131.
Shannon Airport is contactable at 061 712000 and Dublin Airport says passengers should simply contact the relevant airlines.
In the North, the phone number for Belfast International Airport is +44 (0)28 9448 4848, Belfast City Airport can be reached at +44 (0)28 9093 9093 and Derry City Airport at +44 (0) 7181 0784.
Airlines are also promising to refund any passengers whose flights are cancelled due to the terror scare.