Airspace over Iceland's main international airport was shut Friday as shifting winds blew ash from the Eyjafjallajokull volcano west toward the capital of Reykjavik.
The closure marks the first time since the volcano's April 14 eruption that the airport has been shut. Flights on Icelandair that normally stop in Iceland were rerouted through Glasgow.
It was a different story in Europe, where Eurocontrol, the air traffic agency, said flight operations were expected to proceed normally. About 29,000 flights were scheduled Friday.
Europe's airspace was almost ash-free on Friday, and all of Britain's airspace was open after four small airports in northwestern Scotland were cleared to resume operations.
Thousands of European flights had to be cancelled during the past week when winds blew the ash cloud over the continent. About 100,000 flights were halted, at an estimated loss to airlines of about $2 billion.
The massive travel disruption prompted the European Union to speed up reform of its air traffic management system.
"The worst is now over, but there is a huge amount of work to be done to deal with crisis management," said EU Transport Commissioner Siim Kallas.
The EU has 27 national air traffic control networks, 60 air traffic centres, and hundreds of approach centres and towers.
Although air management changes were to have begun in 2012, Kallas said the ash disruptions indicate the Continent cannot wait that long.
"The absence of a single European regulator for air traffic control made it very difficult to respond to this crisis," said Kallas. "We needed a fast, co-ordinated European response … instead we had a fragmented patchwork of 27 national airspaces."
"Without a central regulator, Europe was operating with one hand tied behind its back," he said.
The EU has said it does not want to infringe on national sovereignty issues, but it wants to avoid the unco-ordinated decisions on airspace closure that occurred over the past week.