Safe to fly now? ‘No consensus’ over ash

Passengers rest as they wait for their delayed flights at the Indira Gandhi International Airport in New Delhi, India. The International Air Transport Association says disruptions to European air travel caused by the volcanic ash cloud have cost the industry at least $1.7 billion. (Gurinder Osan / AP) Share Back to slideshow navigation

Relatives of passengers wave to a Lufthansa airplane as it takes off from the airport in Duesseldorf, Germany, on Tuesday, headed for Chicago. Travel chaos in Europe began to ease as some countries resumed flights after days of closures due to volcanic ash clouds from Iceland. (Volker Hartmann / AFP - Getty Images) Share Back to slideshow navigation

People greet family members at Tegel airport in Berlin after they returned from Palma de Mallorca on one of the first flights bringing passengers back to Germany on April 20. (Thomas Peter / Reuters) Share Back to slideshow navigation

A member of the German Air Traffic Control center crisis management group points at a map showing the current air traffic in the sky over Germany near Frankfurt on Tuesday, April 20. The Eurocontrol air traffic agency in Brussels said it expects 55 to 60 percent of flights over Europe to go ahead Tuesday, a marked improvement over the last few days. By midmorning, 10,000 of Europe's 27,500 daily flights were scheduled to go. (Marius Becker / AP) Share Back to slideshow navigation

An aircraft of Air Berlin approaches Tegel airport in Berlin on April 20. Frustrated by the days-long grounding, both Lufthansa and Air Berlin began flying without full air-traffic control. (Gero Breloer / AP) Share Back to slideshow navigation

Passengers sleep at the T4 Barajas airport, in Madrid, Spain, on April 20. Spain offered to let Britain and other European countries use its airports as stopovers to get passengers stranded by the volcanic ash cloud traveling again by train, bus and ferry. (Daniel Ochoa de Olza / AP) Share Back to slideshow navigation

Ash and smoke bellow from the Eyjafjallajökull volcano near Hella, Iceland, on Tuesday, April 20. (Emmanuel Dunand / AFP - Getty Images) Share Back to slideshow navigation

An Icelandic farmer clears ash from a goat house after heavy ash billowing from the Eyjafjallajokull volcano covered this farm in Steinar, Iceland, on April 20. (Emmanuel Dunand / AFP - Getty Images) Share Back to slideshow navigation

A British family prepares to board the Royal Navy warship HMS Albion at Santander's port, northern Spain, on April 20. (Alvaro Barrientos / AP) Share Back to slideshow navigation

When the Eyjafjallajökull Volcano began erupting on March 20, the first lava to erupt came from vents on the lower slopes of the volcano, which were snow-covered, but not under the mountain’s year-round ice cap. Lava flows filled gullies and built mounds of frothy rock, and they melted and vaporized the winter snow, creating relatively small steam plumes. In mid-April, however, the character of the eruption changed dramatically, and this natural-color satellite image from April 17 provides a look at the new eruptive phase. A cloud of charcoal-brown ash covers half the image. A fresh plume of ash rises over the summit, its southern face illuminated by sunlight and its northern face deeply shadowed. The ash column casts a tall shadow onto the snow-covered ground to the north. (AFP - Getty Images) Share Back to slideshow navigation

Huw Thomas, of England, eats his breakfast in his cot at John F. Kennedy International Airport in New York, Monday, April 19. Thomas and his family were originally supposed to fly back to England from a vacation in New York on Friday, April 16, but now they are unsure of when they'll be able to return home. (Seth Wenig / AP) Share Back to slideshow navigation

Molten lava shoots out of an erupting volcano near Eyjafjallajokull, on April 19. An Icelandic volcano that has grounded planes across Europe is spitting lava but less ash, officials said on Monday, offering travellers hope that skies might clear at a faster rate. (Reuters) Share Back to slideshow navigation

Passengers wait for a train to depart to Rome at Milano Centrale train station on April 19 in Milan, Italy. Passengers are looking for alternative routes to return home after days of disruption in air travel as volcanic ash continues to fill the atmosphere over Europe. (Vittorio Zunino Celotto / Getty Images) Share Back to slideshow navigation

Ash covers an evacuated farm as smoke and ash from the Eyjafjallajökull volcano block daylight on April 19, near Porvaldseyri. (Emmanuel Dunand / AFP - Getty Images) Share Back to slideshow navigation

A couple sleeps at Gatwick airport in southern England on April 19. (Carl Court / AFP - Getty Images) Share Back to slideshow navigation

A man crosses an empty departures hall at Gatwick airport in southern England on April 19. (Carl Court / AFP - Getty Images) Share Back to slideshow navigation

A National Geographic film crew sets up on southern Iceland's Eyjafjallajokull glacier after landing close to the volcano on April 18. Scientists say that because the volcano is situated below the glacial ice cap, magma is being cooled quickly, causing explosions and plumes of grit. (Reynir Petursson / Helicopter.is / AP) Share Back to slideshow navigation

A passenger waits at Bilbao airport in northern Spain on April 18, after all flights were canceled due to the ash. (Alvaro Barrientos / AP) Share Back to slideshow navigation

Dairy farmer Berglind Hilmarsdottir of Nupur, Iceland, looks for cattle lost in ash clouds on April 17. (Brynjar Gauti / AP) Share Back to slideshow navigation

Ranchers corral cattle in Nupur as volcanic ash swirls around them on April 17. (Brynjar Gauti / AP) Share Back to slideshow navigation

Volcanic ash is seen over Iceland´s main ring road near Skogar, east of the eruption on April 17. (Brynjar Gauti / AP) Share Back to slideshow navigation

Two flight controllers in Belgrade, Serbia, chat after the closing of airspace over Serbia April 17. (Alexa Stankovic / AFP - Getty Images) Share Back to slideshow navigation

Travelers rest at the deserted Austrian Airlines terminal at the Vienna airport after all flights were grounded on April 17. (Leonhard Foeger / Reuters) Share Back to slideshow navigation

Train passengers crowd the Milan railway station in Italy on April 17. Europeans are turning to different modes of transportation with so many flights grounded. (Luca Bruno / AP) Share Back to slideshow navigation

A reddish sky at sunrise hangs over Budapest, Hungary, on April 17 as ash spewed by Iceland's Eyjafjallajoekull volcano reaches across Europe. (Gyula Czimbal / EPA) Share Back to slideshow navigation

Horses graze as a cloud of volcanic matter rises from the erupting Eyjafjallajokull volcano, on Friday, April 16, in Fimmvorduhals, Iceland. (Nordicphotos / Getty Images Contributor) Share Back to slideshow navigation

Passengers rest on cots as they wait for the resumption of air travel on April 16 at the airport in Frankfurt, Germany. (Torsten Silz / AFP - Getty Images) Share Back to slideshow navigation

Ground staff place a protective cover on the engines of an aircraft at Belfast City Airport in Northern Ireland on April 16. (Peter Muhly / AFP - Getty Images) Share Back to slideshow navigation

Check-in counters are closed at the airport in Duesseldorf, Germany, on April 16. (Oliver Berg / EPA) Share Back to slideshow navigation

Smoke and steam hang over the volcano in Iceland early April 15. Ash from the eruption is drifting into other countries in northern Europe and forcing the cancellation of hundreds of flights. (Brynjar Gauti / AP) Share Back to slideshow navigation

A farmer took this picture of the Eyjafjöll volcano shortly after its most recent eruption on April 14.
• View two versions of this image in PhotoBlog and discuss which you prefer. (Olafur Eggertsson / Reuters) Share Back to slideshow navigation

Rescue teams evacuate residents from rapidly rising waters near the volcano on April 14. (Halldor Kolbeins / AFP - Getty Images) Share Back to slideshow navigation

Rivers of lava flow from a volcanic eruption between the Myrdalsjokull and Eyjafjallajokull glaciers on March 24. (Helen Maria Bjornsd / Getty Images) Share Back to slideshow navigation

Tourists gather to watch lava spurting from the site of a volcanic eruption at the Fimmvorduhals volcano near the Eyjafjallajokull glacier on March 27. (Halldor Kolbeins / AFP - Getty Images) Share Back to slideshow navigation