The Department of Transport has said flights may be grounded for a number of days after an ash cloud from a volcano eruption in Iceland drifted into northern Europe.
Indications are that aircraft will not be able to move tomorrow and perhaps for a number of days Maurice Mullen, assistant secretary of the Department of Transport said after a meeting of the government taskforce on emergency planning this evening.
Departments and agencies involved in the meeting included the Department of Transport, the Department of Foreign Affairs, the Department of Health and Children, the Department of Tourism, An Garda Síochána, Met Éireann, the Irish Aviation Authority and the Dublin Airport Authority.
There are currently "significant" restrictions on flights in and out of Ireland.
The volcanic eruption at the Eyjafjallajokull glacier yesterday threw massive plumes of black smoke and white steam into the air. The cloud has drifted south and is now affecting large swathes of northern Europe.
A spokesman for the IAA, which controls air traffic, said all flights in and out of Ireland may be grounded tomorrow if the ash cloud enters Irish airspace.
He said the Volcanic Ash Advisory Centre in London had advised the authority that the plume of volcanic ash was currently being blown in Ireland's direction. The cloud had initially drifted in south-easterly direction from Iceland down over Scotland and the rest of the UK but it was now being blown back towards Ireland by a north-easterly wind.
"If this volcanic ash plume encroaches into our airspace, and all the signs are that it will tomorrow, then planes will have to stay on the ground," the IAA spokesman said.
Hundreds of flights departing and arriving at Irish and British airports were cancelled today due to the ash cloud.
"It is not safe for aircraft to fly into volcanic dust. The rock particles cause significant damage to the surface of the aircraft skin and the engine components. This dust can cause engines to shut down. The dust particles within a cloud of volcanic ash can also cause electrical faults," the IAA said.
Aer Lingus flights departing and arriving at Dublin, Cork, Shannon, Belfast, London Heathrow and Gatwick Airports have been cancelled for the rest of the day.
The airline said all UK and European flights scheduled to depart Dublin, Cork, Shannon, Belfast, London Gatwick and Heathrow up to 1pm tomorrow have been cancelled. Flights from Ireland to the US are expected to operate with delays, with the exception of flight EI 111 from Shannon to New York which has been cancelled.
Customers holding confirmed reservations on the other transatlantic flights to New York, Boston and Chicago are asked to arrive at the airport on time for check-in.
Aer Lingus said it had activated a change-for-free and refund request facility on its website for affected customers.
Ryanair, which has cancelled all flights to and from Britain and Norway, is also offering refunds or exchanges through its website. The airline, which was forced to cancel about 40 per cent of its scheduled flights across Europe today, said this evening it will not operate any flights to or from Ireland, Belgium, Denmark, Finland, Sweden or the UK before 1.00pm tomorrow.
BMI said it had "reluctantly" cancelled all flights today and some operations tomorrow. It said safety was its number one consideration and that all airlines were affected.
Air France also said it had experienced "severe disruptions" with cancellations and delayed flights. It also had a re-booking procedure in place on its website, it said.
All flights operating through Ireland West Airport Knock were cancelled with the exception of the inbound Ryanair flight FR2451 from Faro and the outbound Ryanair flight FR2452 to Faro. The airport said Aer Arann flight RE220 from Knock tomorrow was also cancelled.
Belfast International Airport and George Best City airport were also closed.
George Best City Airport operations director Mark Beattie said while he hoped it would be back to business tomorrow he could give no guarantee. A spokesman for Belfast International Airport was also unable to give an indication when the cancellations would end.
All intending passengers from all Irish airports are advised to contact their airline.
Irish Ferries reported an increase in bookings and a surge in visits to its website as passengers sought alternative transport. A spokesman for the ferry company said the flight cancellations had a "huge impact" on business and that extra staff were brought in to deal with reservations.
The Jonathan Swift sailing from Dublin to Holyhead at 2.30pm was "sold to capacity" and the 5.15pm sailing from Holyhead to Dublin was also sold out. There was still space for passengers on ferry sailings tomorrow, the spokesman said.
A spokesman for Stena Line said it was "under siege" with intended airline passengers seeking to make alternative arrangements. One ship had sailed at lunchtime "packed to the gunnels". The spokesman said, however, that foot-passenger space was now limited on sailings today and tomorrow.
Airports at Edinburgh, Manchester, Aberdeen, Glasgow and Newcastle are closed. Gatwick, Stanstead, Heathrow and London City airports closed this morning. British Airways said it has cancelled all domestic flights for safety reasons.
The British air traffic control service (Nats) has restricted flights due to ash over northern Scotland but said the ash cloud is expected to move south during the day. The move came a day after similar restrictions were implemented in northern Norway.
A statement on the Nats website said: "We took this decision in order to maintain safety. We continue to work with our neighbouring air navigation service providers to minimise the impact on our aviation customers."
The volcanic eruption threw black smoke and white steam into the air yesterday and partly melted a glacier. The plume of smoke was seen rising from a crater under about 200 metres of ice at the Eyjafjallajokull glacier, close to the site of another eruption which started last month and died down on Monday, Icelandic state radio reported.
Some 700 people were forced out of their homes as melting ice from the glacier caused flooding that threatened to damage a highway and several bridges. "We have had to dig some holes in the road so the flood could pass through and ease pressure on the bridges," said Rognvaldur Olafsson, who is leading the rescue effort.
Three large holes which were visible on the glacier in the morning had turned into a continuous rift running for about two kilometres through the ice, he added.
Scientists had measured increased seismic activity near the glacier about two hours before the volcano started to erupt early yesterday, local media reported.
The volcano, situated beneath Iceland's fifth largest glacier, has erupted five times since Iceland was settled in the ninth century.
Iceland sits on a volcanic hotspot in the Mid-Atlantic Ridge and has relatively frequent eruptions, though most occur in sparsely populated areas and pose little danger to people or property. The last eruption before that in March was in 2004.