The Irish Aviation Authority (IAA) has warned that Irish Airports could again be closed due to volcanic ash.
The Irish Aviation Authority (IAA) has warned that Irish Airports could again be closed due to volcanic ash.
The ash cloud is drifting south towards Ireland due to north easterly winds.
The ash cloud is drifting south towards Ireland due to north easterly winds.
The IAA said current information from the Volcanic Ash Advice Centre (VAAC) suggests that a 'no fly zone' may be imposed over Ireland from Tuesday.
The IAA said current information from the Volcanic Ash Advice Centre (VAAC) suggests that a 'no fly zone' may be imposed over Ireland from Tuesday.
The ban could affect all regional airports. The IAA will have an update from the VAAC at 2000 BST and will make a decison then.
The ban could affect all regional airports. The IAA will have an update from the VAAC at 2000 BST and will make a decison then.
Flights between from the UK and Europe into Ireland are not expected to be impacted on Tuesday. However flights from Ireland could be affected.
Southern airports across the UK Airports are not expected to be impacted.
Flights in Northern Ireland are getting back to normal after restrictions on UK airspace were eased.
On Wednesday, both the International and Belfast City Airport said they operated at about 50% of their usual flight schedule.
All flights from Belfast City Airport will operate as normal on Thursday, apart from Ryanair, which will resume its flights on Friday.
Travellers are advised to check with airlines before going to the airport.
An estimated 120,000 passengers were affected by the closure of NI airspace six days ago.
The first set of stranded passengers arrived back in NI on Tuesday evening.
On Wednesday, a spokesperson for the George Best City Airport said that 50% of all flights got away.
A full service is expected on Thursday with the exception of Ryanair which is due to resume flights on Friday at 0600 BST.
At Belfast International Airport, spokesperson Uel Hoey said about 60% of its flights took off.
At the City of Derry Airport Aer Arann flights on Wednesday morning were cancelled, but the airline said the evening service to Dublin would operate.
The airports are urging people to check with their airline before travelling as it is likely to take days before schedules are back to normal.
LATEST ON FLIGHTS BA: All long haul flights from Heathrow and Gatwick; some short haul cancellations on Wednesday Virgin Atlantic: Normal schedule from Heathrow and Gatwick; Passengers booked on 15 April overseas departures also due to return to UK Thomson: Outbound flights cancelled until Thursday Easyjet: Intends to operate 90% of flights Ryanair: Northern European flights to resume 0500 BST on Thursday including UK to continental Europe Flybe: Operating most scheduled flights BMI: Increasing flights out of Heathrow on Thursday, with more than 90% of international flights and 50% of domestic flights due to operate *Passengers are advised to contact their airline before travelling to an airport for a flight
Siobhan Moore from Dublin Airport said it would be a "phased return to business".
"There will have to be a lot of repositioning of aircraft, so it is a big logistical challenge for the airlines to catch up on this."
However, the Irish Aviation Authority (IAA) has warned that it may take up to three days for full services to resume.
The IAA emphasised that the lifting of restrictions is subject to the ash cloud not moving over Ireland and no further aggressive activity from the volcano in Iceland.
It said: "The IAA continuously monitors the situation and will issue a statement if the exclusion zone threatens Irish airspace today or in the days to come."
Risk assessments
The flight restrictions were introduced following the eruption of the Eyjafjallajokull volcano in Iceland which sent a plume of ash into the atmosphere.
Experts say the tiny particles of rock, glass and sand contained in the ash cloud could jam aircraft engines, as has happened in previous incidents of planes flying into plumes of volcanic ash.
ANALYSIS By Pallab Ghosh, science correspondent, BBC News
The question the airline industry is asking is why did it take six days for the Civil Aviation Authority to change its policy, and what does it know now that it did not know a week ago.
Part of the problem faced by the regulator is that there is a limited evidence base with which to make an accurate risk assessment.
Such occurrences are rare so the policy seems to have been one of safety first.
But as the flight ban wore on, with increasing numbers of passengers stranded and the cost to the airline industry rising, the CAA was forced to reassess its policy.
It consulted extensively with jet engine manufacturers and gathered new evidence from test flights through the volcanic ash.
This process led the regulator to conclude on Tuesday night that planes would not stall if they flew through low concentrations of the ash.
The restrictions were lifted after the Civil Aviation Authority said safety tests showed plane engines had "increased tolerance levels in low ash density areas".
It has set down new requirements for airlines such as conducting risk assessments and inspecting aircraft for ash damage before and after each flight.
Prime Minister Gordon Brown defended the time taken to reopen UK airspace, saying decisions had been based on "scientific advice".
"We would never be forgiven if we had let planes fly and there was a real danger to people's lives," he said.
Transport Secretary Lord Adonis said the ban was lifted after a "robust safety assessment" based on observational data and test flights.
"The whole of Europe has been in the same position, acting according to the same aviation safety rules," he said. "European safety regulators have been working to properly understand the impact of the ash cloud which has come from Iceland."
Lord Adonis denied the decision to reopen the airspace was the result of pressure from the airline industry.
Frances Tuke, spokeswoman for travel body Abta, said the return to normality would be slow and there was also a risk the ash cloud could return.
"The thing to remember is that aircraft and crew are going to be in the wrong place," she said.
"I know for example that some of our tour operators have decided to cancel their programmes going out of the UK in order to reposition their aircraft and crew. It's a huge logistical operation."
The International Air Transport Association estimated airlines had lost about $1.7bn (£1.1bn) as a result of the travel disruption. Easyjet put its expense at £50m.
