Ash from a volcanic eruption in Iceland has forced the cancellation of flights to and from some of Ireland's airports and prompted warnings of further disruption.
Travel plans were thrown into disarray for hundreds of passengers while even US president Barack Obama was forced to amend his itinerary, flying from Ireland into London earlier than planned to avoid the dense plume drifting towards the UK.
Forecasters predicted the volcanic cloud, which billowed from Iceland's Grimsvotn volcano, would hit Scotland and Northern Ireland in the coming hours.
Among the airlines affected, Aer Lingus said it had cancelled 12 flights to and from Glasgow, Dublin, Aberdeen, Edinburgh, Shannon and Cork.
Meanwhile, Ryanair bosses said they would meet Irish officials later in a bid to have flight restrictions lifted.
Ryanair said it objected to advice from the Irish Aviation Authority (IAA) not to operate flights to and from Glasgow, Prestwick, Edinburgh or Aberdeen until at least 1pm.
In a statement on its website, the airline said: "Ryanair strongly object to this decision and believe that there is no basis for these flight cancellations and will be meeting with the IAA on Tuesday morning to have this restriction on Ryanair flights removed as a matter of urgency.
"Ryanair believe that there is no safety risk to aircraft on fights operating to and from Scotland and together with other airlines will be complaining to the Transport Minister and regulatory authorities about these latest and unnecessary cancellations."