Passengers should continue to check with their airline
Flights in and out of Cardiff airport have resumed hours after it closed because of new problems with a volcanic ash cloud from Iceland.
The airport was among many across the UK and Ireland scheduled to close between 0700 BST and 1300 BST.
Others in the no-fly zone included Bristol and Birmingham. Heathrow and Gatwick have re-opened, but with many delays and cancellations expected.
Passengers are advised to check with airlines before leaving home.
The airport is warning disruptions and cancellations remain in place following the disruption.
Seven flights remained cancelled on their website, with others reporting delays.
Swansea Airport, which has no scheduled flights, has also been affected.
All flights in Northern Ireland and much of Scotland have been grounded until 1300 BST.
Glasgow, Manchester and Stansted airports remain open.
No flights will be arriving at Gatwick until after 1300 BST.
Air traffic authority Nats said of the latest ash cloud: "Two key areas affect operations stretching from south England to Northern Ireland, and over much of mainland Scotland to the Shetland Isles.
"As a result, no-fly zones have been imposed by the Civil Aviation Authority in these areas, for the period 7am until 1pm.
"Airports within the no-fly zones include all those in Northern Ireland, Ronaldsway, Edinburgh, Aberdeen, Inverness and Northern Scotland.
"Cardiff, Swansea, Bristol and Farnborough are also in the no-fly zone.
"Heathrow and Gatwick airports will be clear of the no-fly zone, however restrictions will have to be applied due to their close proximity to the no-fly zone, particularly affecting Gatwick inbounds."
The Eyjafjallajokull volcano in Iceland first began erupting a month ago, and after triggering a six-day shutdown of airspace across many parts of Europe in April, it is continuing to cause intermittent disruption owing to fresh eruptions of ash.