Will Volcanic Ash Stop? Some Flight Restrictions Relaxed as Icelandic Eruption Continues

May 19, 2010— -- Flying to and around Europe these days can seem a bit like spinning a roulette wheel as governments there periodically impose flying bans because of ash from Iceland's Eyjafjallajokul volcano.

On Monday alone, 1,000 flights were canceled mostly in Britain and the Netherlands.

But now, British aviation authorities are loosening their restrictions so that more planes can fly during the eruption.

Just how long the volcano will continue spewing dangerous ash into the skies over Europe is anyone's guess. Scientists monitoring the eruption at Eyjafjallajokul are still detecting dozens of small earthquakes beneath the volcano, suggesting that magma is still building up from deep in the earth and will continue to feed the volcano.

And let's not forget that the last time Eyjafjallajokul erupted, in December 1821, it did not stop for nearly 14 months.

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So with the key summer travel months nearly here, the United Kingdom's Civil Aviation Authority -- facing political pressure and accusations it overreacted -- has decided to change its threshold for what it deems safe conditions for flying.

The CAA created a new "Time Limited Zone" that approved airlines can fly through briefly at higher ash concentrations. The new rules, which went into effect Tuesday, allow flights if there are up to 0.004 grams of ash per cubic meter of air, twice the prior limit.

The British government said it created the new rules after talking with aircraft and engine manufacturers, establishing what level of ash planes can safely handle.

"Unprecedented situations require new measures and the challenge faced should not be underestimated," Andrew Haines, the head of the CAA said in announcing the new rules.

Haines added that the default procedure for aircraft to avoid ash completely "doesn't work in our congested airspace" and that "the world's top scientists tell us that we must not simply assume the effects of this volcano will be the same as others elsewhere."

"Its proximity to the U.K., the length of time it is continuously erupting and the weather patterns are all exceptional features," he said.