Ash from a volcano in Iceland has cleared the skies of aircraft across much of northern Europe, with planes grounded on a scale previously unseen.

 

The highly abrasive, microscopic particles that make up volcanic ash, pose a major threat to aircraft. They can affect visibility and cause damage to engines, causing them to shut down.

Britain's air traffic service halted all non-emergency flights until at least 7 a.m. Friday.

Airport shutdowns and flight cancellations spread across northern Europe - to France, Belgium, the Netherlands, Denmark,Norway,Ireland, Sweden, Finland and Switzerland - with the knock-on effects felt worldwide.

Airlines in the United States have cancelled some flights to Europe and delayed others. Flights from Asia, Africa and the Middle East to London and other major European hubs have also been put on hold.

Most passengers are philosophical.

Katarina Karlsson, Passenger, said, "Its cancelled because of the eruption on Iceland. Its sort of interesting because all the travellers are in the same situation and you can't get annoyed at nature!"

A scientist in Iceland said it was impossible to predict how long the ash would cause problems to air traffic.

Magnus T. Gudmundsson, Professor of Geophysics Univ. of Iceland, said, "There are no easy options here, this eruption may stop tomorrow, but it may continue to disrupt air traffic for weeks or months."

Eurocontrol, Europe's aviation control agency says disruption to air traffic could last another 48 hours.