Disruption to flights has eased as the volcanic ash cloud has moved away from British air space.
National Air Traffic Services (Nats) says all airports across the UK are expected to open after restrictions lifted at 7am.
Airports in the Republic of Ireland have also begun reopening after the Irish Aviation Authority (IAA) lifted restrictions there.
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."
Travellers in Scotland, Northern Ireland and the Republic of Ireland were left stranded on Wednesday by the cancellation of hundreds of services, with CAA chief executive Andrew Haines warning the ash cloud could cause disruption for "the foreseeable future".
"The situation for UK airspace, particularly over the North and Scotland, remains unprecedented.
"Scientists are tracking the cloud's movements constantly but its location changes frequently, depending on the strength of eruptions and prevailing winds.