All UK airports were open for business this morning after the volcanic ash cloud drifted away from British airspace.
National Air Traffic Services (Nats) said all airports across the UK reopened at 7am.
Airports in the Republic of Ireland reopened at 4am after the Irish Aviation Authority (IAA) also lifted restrictions.
A statement from Nats said: "The no-fly zone imposed by the Civil Aviation Authority tracking the high density area of the volcanic ash cloud has moved west overnight and has now cleared UK airspace."
Yesterday, travellers in Scotland, Northern Ireland and the Republic of Ireland were left stranded by the cancellation of hundreds of services.
Passengers seemed uncertain as to which airports were operating flights, a problem highlighted by Scotland's First Minister Alex Salmond, who accused the CAA of releasing a "vague" statement on Tuesday night which suggested all Scottish airspace would be closed when Edinburgh and Aberdeen Airports were open for the first part of the day.
Mr Salmond said: "Unnecessarily, some flights were cancelled, particularly into Edinburgh, because of the vagueness of the press release they (the CAA) put out.
"That can't be allowed to happen again. It's really, really important, where there are difficult messages, that press statements must be clear and not cause confusion."
Mr Salmond added that the CAA had since apologised.
CAA chief executive Andrew Haines yesterday warned that the ash cloud could cause disruption for "the foreseeable future".
"The situation for UK airspace, particularly over the North and Scotland, remains unprecedented.
"Volcanic ash is a known hazard to aircraft and the previously accepted procedure adopted all over the world was to avoid ash completely.
"For the first time an ash cloud is affecting airspace where there is not the room to do this. So the CAA had to develop new safety procedures enabling flights to continue whilst flying close to or through the ash cloud.
"We were able to reopen the skies last month, having secured agreement from manufacturers on safe levels of ash tolerance.
"Scientists are tracking the cloud's movements constantly but its location changes frequently, depending on the strength of eruptions and prevailing winds.
"When the ash level exceeds that agreed as safe by the industry we have to restrict flights accordingly.
"This decision is not taken lightly and we appreciate the huge inconvenience and disruption this causes to the many people and businesses affected.
"Ash is likely to continue to disrupt UK air travel for the foreseeable future and our advice to passengers is to listen to updates and contact their airline before leaving home if they are concerned their travel plans may be affected.
"The CAA is continuing to lead international efforts to develop more detailed scientific understanding of the situation to minimise disruption without compromising passenger safety."
There was early-morning uncertainty at Dublin Airport yesterday with a number of passengers arriving for flights only to find there were no services.
And at Belfast International and Belfast City Airports, where the no-fly ban was not introduced until 1pm, some passengers failed to turn up, unaware that the airports were operating during the first part of the day.
One of those hit by the axing of services was Mabel McGeachie, 62, from East Kilbride, Scotland, who had her easyJet flight from Glasgow cancelled.
She had been due to travel to Malaga in Spain with 10 friends and relatives for her daughter's hen night and was told the next available flight was on Sunday - the day she was meant to return.
"We are feeling disappointed as we were looking forward to it and I don't think we'll be able to rearrange it. It was my daughter's hen do and her wedding is in July.
"We heard about the ash last night but just came down to the airport anyway."
Scottish football club Ross County had to scrap plans to fly from Glasgow to Marbella in southern Spain to train ahead of their Scottish FA Cup final against Dundee United on May 15.
The club's director of football, George Adams, was philosophical, saying: "We were looking forward to it but you get on with life.
"Lots of people have been disrupted with the volcanic ash and we're no different from anyone else."
Airline bmi said all its Heathrow services were now back to normal. There were some cancellations of Ireland flights to and from Heathrow.
Ryanair's flights to and from Shannon airport in Ireland were due to restart at 10am, with flights to and from Kerry airport restarting at 8.50am.
The low-fare carrier added that it would be putting on extra flights between the UK and Ireland this afternoon and evening.