Aer Lingus and Ryanair have been forced to cancel a number of flights in and out of Scotland today, because of the threat of volcanic ash from Iceland.
Any intending passengers are being advised to check with their airline before leaving home.
European officials have said that authorities are in a better position to deal with volcanic ash disruption now than they were a year ago.
However, they have also pointed out that "volcanoes don't obey rules", and the situation evolves by the hour.
This morning, 12 Aer Lingus flights from Cork, Shannon and Dublin to airports in Scotland have been cancelled because of the disruption.
A statement from Ryanair lists 36 flights on their schedule which have been scrapped.
The companies reacted angrily to advice not to fly to or from Glasgow Prestwick, Edinburgh or Aberdeen until at least 1pm today.
Further information is expected from the Irish Aviation Authority at around 9am today, after officials consult with the Volcanic Ash Advisory Centre in London.