Hundreds of flights have once again been grounded as a volcanic ash cloud looms over Ireland and parts of Scotland.
Thousands of travellers will face severe delays after a six hour no-fly zone was imposed across the Republic and Northern Ireland.
Airspace over the Outer Hebrides was also closed to operations on Monday night, while airlines warned passengers to avoid travelling to airports without checking departure information online.
The Irish Aviation Authority (IAA) and UK’s Civil Aviation Authority (CAA) are monitoring the situation.
Eamon Brennan, IAA chief executive, said that, based on the new regime imposed in Europe last week, officials had no choice but to impose a no-fly zone from 7am to 1pm.
“The decision is based on the safety risks to crews and passengers as a result of the drift south of the volcanic ash cloud caused by the north easterly winds,” he said.
The situation will be reviewed again at 9am.
Almost 440 flights had been due to depart and fly in to Dublin Airport throughout today, with more scheduled from Shannon, Galway, Sligo, Knock, Donegal, Cork and Kerry.
Ryanair cancelled all its flights to and from the Republic of Ireland, Belfast and Derry City from 6am to 2pm, with Aer Lingus suspending all Irish services to the UK and Europe until 1pm.
However all but one of its transatlantic services to the US will operate, subject to delays.
Aer Arann has been forced to cancel services to and from Derry and Donegal airports while easyJet warned of possible disruptions on services to Northern Ireland and Scotland.
The closure of Outer Hebrides airspace has hit operations from Stornoway, Tyree, Barra and Benbecula.
The CAA confirmed there would be a no-fly zone over Northern Ireland from 7am, meaning Belfast International, Belfast City and City of Derry airports would be closed.
Irish Ferries said it had space on its services between Ireland and the UK and Ireland and France.
Flights from continental Europe will not be impacted by the plume of ash from Iceland’s volcano Eyjafjallajokull, which caused travel chaos for almost a week last month.
