Hundreds of trans Atlantic flights have been cancelled or delayed by a cloud of ash from an Icelandic volcano drifting south over Western Europe.
Sixteen Spanish airports - including Barcelona - are closed. Many flights are being re-routed around the affected area.
However, Zaragoza, Valladolid and Salamanca airports are now open again.
On average, 600 airliners make the Atlantic crossing every day.
The Spanish government said there was a chance the cloud, which is 2000km long, could still affect the country next week.
Transport Minister Jose Blanco said extra places on long-distance trains would be made available, and extra buses and boats were being laid on.
The BBC reports some flights from Britain to Spain were being affected.
At London's Stansted airport, 22 Ryanair flights to the Canary Islands, mainland Spain and Portugal were cancelled, along with three EasyJet flights.
Flights from Gatwick to Portugal, Alicante and Madrid were cancelled. At Heathrow some flights to La Coruna in northern Spain were also grounded.
Recent images have shown activity in the Eyjafjallajokull volcano intensifying.
The UK Met Office said it was sending ash up to heights of 30,000 ft (9,100m).
Flights across Ireland and parts of Britain were disrupted earlier this week.
The volcano began erupting on 14 April, causing airspace to be closed over several European nations for a week.
More more than 100,000 flights were cancelled and eight million passengers affected. The airline industry said it lost about 2.5 billion euros.