The volcanic ash cloud has moved away from British airspace and all UK airports have subsequently opened for business.
All airports across the UK reopened at 7am on Thursday, the National Air Traffic Services (Nats) said.
After restrictions were also lifted by the Irish Aviation Authority airports in the Republic of Ireland reopened at 4am.
As planes take to the sky again above the UK and Republic of Ireland, the wrangling between passengers and their travel insurance companies continues. Different insurers have different attitudes to so-called "acts of God" and so travellers may or may not be covered for resulting delays and cancellations caused by the volcanic ash disruption.
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."
On Wednesday, 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.
There was early-morning uncertainty at Dublin Airport on Wednesday 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.
© Press Association 2010