Much of the northern and western European air space was closed Friday, with more than half of all flights canceled.
The chaos was sparked by a volcano that erupted under the Eyjafjallajoekull glacier in Iceland and has since sent a cloud of ash across Europe.
Britain, Ireland, Denmark, Sweden, Finland, Belgium, the Netherlands, France, Germany, Austria and the Baltic nations shut down airports, BBC News reports.
Germany's Lufthansa, one of Europe's largest airlines, canceled all of its European flights until midday Saturday.
Hundreds of thousands of passengers have been stranded at airports all over the world, with the chaos likely continuing during the weekend, as the ash moves across the continent.
Experts said they hope flights can be resumed early next week: The volcano is still producing ash but its eruptions have become weaker.