Icelands volcanic ash brings air traffic to halt in Europe

Matthew Watson,a specialist in the study of volcanic ash clouds from Bristol University in England,said the plume was likely to end up over Belgium,Germany,the Lowlands,and was unlikely to disperse for 24 hours.

British aviation officials said the countrys airspace would remain closed at least until 7 am on Friday,meaning that no flights other than authorised emergency flights would be permitted. All of the roughly 6,000 scheduled flights that use British airspace each day would be affected,aviation experts said.

Eurocontrol,the European air traffic agency,told news agencies in Brussels that disruptions in the region could continue for another 48 hours,and could extend into more countries. France said it was closing 24 of its airports.

The volcanic ash was reported to be drifting at 18,000 to 33,000 feet above the earth. At those altitudes,the cloud is directly in the way of commercial airliners,the England-based International Volcanic Health Hazard Network said on its website.

The impact on travel was likely to be among the most severe in many years,cutting trans-Atlantic links and severing air routes across northern Europe.

Major American carriers that fly to Britain were allowing their passengers to rebook flights without penalty on Thursday. United Airlines offered waivers on flights through Friday on its website.

In Terminal 4 at Heathrow,where flights leave London bound for Houston,New York and Paris,among many other destinations,all check-in counters were closed. Arrival and departure boards listed all flights as canceled. Airport staff in yellow slickers handed out fliers offering apologies and saying the closure was due to the volcanic dust cloud from Iceland.

In parts of Scandinavia,too,air travel came to a halt. In Norway,all flights to and from Oslo Airport were canceled as of 10 am local time,the airport said in a statement on its website. In Sweden,the aviation authority gradually closed its airspace during the day,though several airports,including Arlanda and Bromma airports in Stockholm,will remain open until 6 pm on Thursday,said Susanne Rundstrom,a spokeswoman for Swedavia,which operates the countrys 14 airports.

The Finnish aviation authority,Finavia,warned travelers to expect some flight delays and cancellations,though a spokeswoman said all of the countrys airports would remain open for now.

A spokesman for the Irish Aviation Authority said that several sections of Irish airspace,including Dublin,would be closed.

Although volcanic ash clouds sometimes limit pilots visibility,their most serious safety threat to aircraft is the harm they can cause to engines in flight. Volcanic ash is made primarily of silicates,or glass fibers,which,once ingested into a jet engine can melt,causing the engine to flame out and stall.