Air travel through British airspace, and a few points beyond, is once again being affected by a volcanic ash cloud making its way south from Iceland.
In Northern Ireland, Scotland and England, some airports were completely shutdown. Ireland saw some closures, as did airports in the Netherlands.
Having experienced a six-day shutdown last month, airline regulators and the aviation industry are now working more closely in refining the scope and impact of this cloud.
British Transportation Secretary Philip Hammond says all parties are learning more about how best to deal with this potential threat that could reappear in the coming months.
"My officials have been working into the night, last night, with the CAA [Civil Aviation Authority] and with the aircraft engine manufacturers, trying to reach a consensus on a higher threshold operating level with an enhanced inspection regime that would allow aircraft to fly for short periods through densities of volcanic ash higher than the current threshold and to do so safely by having a proper enhanced inspection regime in place," saidHammond.
At Britain's National Air Traffic Service, they have been keeping close tabs on the size and density of the ash formation. Operations Director Ian Hall says the shape and location of the cloud changes by the hour.
"The ash, which has been sweeping down from Iceland over the British Isles has effectively split into two areas: one affecting some of the Scottish airports, and the other one then sweeping down and around to the south of London, perilously close to Heathrow, which is landing 30 aircraft an hour instead of the normal 42 aircraft an hour, and so close to Gatwick that the aircraft are able to depart but not to land," said Hall.
About 1,000 flights have been canceled in Europe, but that is substantially less that the daily average affected last month by the ash cloud.
Throughout Monday, more airports re-opened, allowing at least some restricted flights. But, on an individual basis, stories of frustration abound. These passengers stranded in Edinburgh say airline information has not been good.
"They do not know anything, nothing at all. We will just come back, and, when they get their update, they might know a little bit more," said one passenger. "We checked at 4 o'clock this morning, Edinburgh airport was still open and the flight was still scheduled, but you get here at half past six and they told us it was canceled," the passenger added.
Forecasters predict flight delays and cancelations could remain for another day, but winds are expected to move the volcanic air mass into northern Europe on Wednesday.
When it is gone, some travelers here will still face problems as the airlines cope with a backlog of passengers.
To compound matters, cabin crews at British Airways planned to go back on strike Tuesday as part of their lengthy dispute with management, but a last-minute court ruling has stopped the strike and more conciliation talks are scheduled.