Fears of horrendous transport problems as caused by an Icelandic volcano last were inevitably raised by the confirmation from the German Weather Service (DWD) that the ash was heading for Germany.
And with ash concentration likely to rise to between 0.2 and 2.0 milligrams per cubic metre, flights in the region will require special supervision by air traffic authorities.
German officials said on Monday they saw no danger of major disruptions to air travel at present, but announced new rules to help avert the chaos caused by a previous eruption in 2010.
Transport Minister Peter Ramsauer said the new rules included a ban on non-emergency flights if the concentration of volcanic ash is more than 2.0 milligrams per cubic metre.
"A recent study has shown once again how harmful volcanic ash particles can be for aircraft and their engines," Ramsauer said in a statement. "With our measures in place, Germany is well prepared. But an internationally-agreed and uniform approach within the European Union remains necessary."
Iceland's airspace, which was closed shortly after the volcano began spewing ash at the weekend, was partially reopened Monday but the main Keflavik airport, near the capital Reykjavik, remained closed, officials said.
A number of airlines cancelled flights in and out of Scotland on Tuesday, while US President Barack Obama left Ireland for London ten hours early to avoid any possible delays due to the ash.
But meteorologists do not expect the situation to become as bad as last year, when the eruption of the Eyjafjoell volcano caused more than 100,000 flight cancellations.
Some eight million passengers were stranded for weeks, dealing a harsh blow to the airline industry, particularly in Europe.