London, England (CNN) -- Volcanic Ash From Iceland Severely Disrupted Air Traffic Across Europe For A Second Day On Friday, Causing The Cancellation Of Some 17,000 Flights, According To The Intergovernmental Body That Manages European Air Travel.

Eurocontrol Said It Expected Around 11,000 Flights To Take Place Friday, In Contrast To The Normal 28,000. The Impact Will Last At Least Another 24 Hours, Eurocontrol Said Friday Morning.

The Ash Has Spread To Parts Of Northern And Eastern Europe And Has Forced The Closure Of Some Of Europe's Busiest Airports, Causing More Disruption To Worldwide Air Travel Than 9/11.

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Airspace Over Much Of The United Kingdom Was Closed To All Flights Except Emergencies At Least Until 1 A.m. Saturday (8 P.m. ET Friday), Britain's Air Traffic Authority, NATS, Said. Select Flights Were Being Allowed In Northern Ireland And Scotland, And Some North Atlantic Traffic May Be Allowed To Those Areas, It Said.

Video: German Air Traffic Closed Due To Ash

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Gallery: Volcano Ash Causes Travel Chaos

NATS Called The Situation "dynamic And Subject To Change."

Airspace Was Also Closed Over Belgium, Denmark, Finland, Lithuania, Estonia, And The Netherlands, And Airspace Was Partially Closed In France, Germany, Poland, Sweden, Norway, And Ireland, Eurocontrol And Local Authorities Said.

Norway's Airspace Closure Included Cancellation Of Helicopter Flights To Off-shore Oil Installations.

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The French Closure Included All Paris Airports, Though Landings Were Being Allowed At Those Airports During A Four-hour Window Friday Afternoon, The DGAC Civil Aviation Authority Said.

Germany's Closure Included Airports In Berlin, Frankfurt, And Duesseldorf, Eurocontrol Said. Warsaw Airport In Poland Was Closed, Which May Affect Plans For World Leaders To Attend The Scheduled Sunday Funeral Of Polish President Lech Kaczynski; A Spokeswoman Said Krakow Airport Remained Open But Had An Extremely Limited Schedule.

Air Transport And Weather Authorities All Over Europe Are Working Together And With The Airlines To Discuss The Continued Impact Of The Ash Cloud, British Transport Secretary Andrew Adonis Said.

He Said He Would Discuss Contingency Plans With Key Transport Officials Friday Just In Case The Situation Continues.

The U.S. Air Force Said Thursday Two Bases In England, RAF Mildenhall And RAF Lakenheath, Will Be Shut Down For At Least Two Days. That Meant Dozens Of U.S. Air Force F-15s And Other Fighter Jets And Tankers Are Not Flying, And Flights To Iraq And Afghanistan Flying Through That Airspace Are Being Diverted To Other Routes.

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English Channel Ferry Operators And Eurostar, Which Runs High-speed Trains Between London, Paris, And Brussels, Said They Were Experiencing An Extremely High Demand As Passengers Seek Other Ways Of Getting To Their Destinations. Adonis Said Eurostar Had Added Services To Cope With Demand.

Passengers Who Spoke To CNN At Heathrow's Terminal 1 Seemed Resigned To Having Missed Their Flights.

"I Don't Want The Plane Going Down. This Is Really Dangerous," Said One Man. "But I've Been In Some Different Situations Over The Years, And This Is A New One."

One Woman Said She Had Missed A Wedding Because Of The Problems.

"Not Sure If We're Still Going To Go Or Not," She Said. "I Don't Know That There's Any Point Any More, 'cause We've Missed Everything The Trip Was Ultimately For."

Those Passengers Stranded At Frankfurt Airport Were Being Given Food And Supplies. Spokesman Robert Payne Said Authorities Distributed 1,000 Cots Along With Cold Drinks, Hot Soup, Bread, Baby Food, Diapers, And Toiletries.

Delta Air Lines Canceled 65 International Flights From Its U.S. Hubs Scheduled Over Thursday Night And Friday Morning In Response To The Ash Cloud. The Decision Affected Flights To Amsterdam; London; Shannon, Ireland; And Brussels In Europe And To Mumbai In India. Whether The Airline Resumes Flights To Such Destinations Will Be Determined Later Friday, Delta Said.

Air China Announced The Cancellation Of Most Of Its Friday Flights To Europe.

Hong Kong-based Cathay Pacific Also Canceled Or Delayed Flights From Hong Kong To London, Paris, Frankfurt And Amsterdam.

Volcanic Ash Can Cause Jet Engines To Shut Down.

It's Hard To Predict How Long It Will Be Before Air Travel Can Resume, Said Matthew Watson, A Geophysicist, At England's Bristol University.

"You Really Need Two Things To Happen: You Need The Volcano To Stop Emplacing Ash To The Altitude That Commercial Aircraft Fly At, 30-35,000 Feet, And You Then Need The Upper Level Winds To Blow The Ash And Disperse It Out Of The Airspace," He Told CNN.

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How Long That Will Take "depends Very Much On The Volcano. If This Is It And It's Stopped Right Now And It Doesn't Do Anything Else... I Imagine You Are Looking At 24 To 48 Hours To Clear U.K. Airspace," He Said.

The Closures Came After An Eruption Under An Icelandic Glacier Early Wednesday. The Eruption Under The Eyjafjallajokull Glacier -- The Latest In A Series That Began On March 20 -- Blew A Hole In The Mass Of Ice And Created A Cloud Of Smoke And Ash That Went High Into The Air.

The Volcano Was Still Erupting Friday And Producing A Lot Of Volcanic Ash, A Spokesman For Iceland's Department Of Civil Protection And Emergency Management Told CNN.

"The Volcanic Ash Particles Are Very Fine And Have Been Compared To Flour And Sugar In Size," The Department Said Friday. "The Flourine Content Of The Ash Is High And Presents A Health Risk To Livestock In Areas Where The Ash Layer Is More Than 1 Centimeter Thick."

Dust And Odors Were Detected Thursday In The Northern Isles In Scotland, The British Weather Service, The Met Office, Said Friday. The Scottish Environment Protection Agency Is Now Analyzing The Dust.

The Met Office Said The Volcano Is Spewing Ash In "pulses," Not A Steady Plume.

An Emergency Evacuation Affecting 800 People Was Conducted Near The Volcano Due To Flash Flooding From Glacier Waters, According To Rognvaldur Olafsson Of Iceland's Civil Protection Agency. The Same People Had Fled The Area The Night Before And Allowed To Return To The Area Early Thursday.

The Ash Wasn't Necessarily Visible In The Air, But Manchester Airport Spokesman Russell Craig Said It Can Still Pose A Threat To Aircraft.

"If You Think About The Way An Aircraft Engine Works, It Sucks In Air, It Compresses It, Forces It Out On The Other Side. That Creates Thrust," Craig Told CNN.

"If That Air Were Mixed With Ash, It Can Cause Engine Failure And Electrical Difficulties With An Aircraft. It's Happened Before, And The Aircraft Didn't Come Out The Other End In One Piece."

CNN's Bharati Naik, Melissa Gray And Ed Payne Contributed To This Report.