AtlanticFlamethrower

Big news! So it was all a big scare from the UK Met Office and it will all be sorted out in time for the next party leaders' debate this Thursday.

How many people have died on the roads because of the pointless blanket ban on flights? It's a fair question to ask.

This would be relevant if the training exercises last 15 minutes. My guess is they last longer than that, perhaps over an hour even. Any RAF pilots reading??

Good question. My guess is there aren't enough of them and they are being used in places like Afghanistan.

The second principle of good science should be to disregard appeals to authority.

They would be going very near full speed on training missions. If you want to be scared, be scared. But there are other people who think it is just as logical not to be scared because the claims being made are not matched by relevant evidence. In fact these people are angry because they can't get home and their livelihoods are suffering while good ol' Gordo is playing Lord Nelson.

Imagine a whale moving through the ocean at 20 knots. Whales survive by filtering plankton. Every day one whale consumes something like a tonne of plankton, just by moving through the water and filtering it for plankton. Let's say the whale can move faster than 20 knots - 40 knots. Do you think the amount of plankton the whale would eat in one day would be the same, more or less? The whale would eat more plankton the faster it swam. Same principle with planes and the sand-blasting effect on jet engines. F-16s can fly up to mach 1.6. Sand not only enters the jet engine much faster at high speeds but sand enters at a higher density because the jet engine is going faster. It's like when you walk in the rain you don't get your front splattered, but when you run you feel the air rushing by your face and you get your clothes drenched. What is true for 1100mph jet fighters might not be true for transport planes which fly at 500 mph, or less. Transport planes have flown with no dust effects. That is the evidence that matters to civil aviation.

I accept not all the ash has dropped out of the sky. And right now the UK is in the direct line of fire so we might expect to have the higher concentrations now. But a blanket ban on the rest of Europe is wholly unnecessary, and there may even be parts of UK and Ireland that are safe to fly.

Newsflash: the Met Office models that policy makers use to make a threat assessment are based on pollutants - gasses - rather than dust particles. The dust solids emitted in volcanic ash are 10 microns across. This is about 20,000 times larger than a molecule of gas. That's like modelling the spread of a bag of marbles thrown up in the air using a model designed to model the spread of dust! The models which have caused this scare are not a reliable predictor of what dust is up in the air. No wonder planes which have flown up have found no problems - the dust has already all dropped out of the sky and onto our cars. All the Met Office models show now is virtual reality dust that does not actually exist.

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/ Thanks. To be fair you don't need a PhD to observe the lack of earthquakes around Katla - i.e. the myrdalsjokull glacier. It all seems to over, at least for now.

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/myrdalsjokull/ Thanks. To be fair you don't need a PhD to observe the lack of earthquakes around Katla - i.e. the myrdalsjokull glacier. It all seems to over, at least for now.

You mean this graph?

You veggie. What about my Danish bacon, New Zealand lamb chops and German sausages?

One thing to consider about the Finnish jet - the faster you fly the more damage the dust will do to the engine. An F-18 jet planes goes 1100 mph while a 747 at maximum goes half that. Fly at the speed of sound through the core of a volcanic plume and you're asking for damage. Fly a 747 at half speed through the outer bands of the plume and you will sustain much much less damage. I can't quantify this but aircraft technicians presumably could.

KLM say they would not fly in that area - Iceland-Russia. They want to fly in the pockets where the dust is negligible. ESK is the one nearer Katla, isn't it?

Businesses employ people who have lives to live and taxes to pay to the government. Money does matter. Dust is expensive. The no fly zone will have an effect on the supermarket shelves, medicines and high-tech goods delivered to this country. Long enough, it will cause social disruption. A blanket ban based on fear of what "might happen" has severe costs and these should be weighed up against the costs of being slightly more flexible allowing planes to take advantage of lower dust levels, which can be assessed by satellites, weather balloons, military planes.

Some would say this is electioneering.

These pockets are not as dense as those which caused the KLM867 flight problems. The zero-tolerance ban is based on computer models of a volcanic explosion the size of Katla - and ey-a-loke is moderate compared. In some areas the dust thickness must be no greater than a summer plume from the Sahara. We should at least consider whether we could raise the threshold dust tolerance level before planes are allowed to fly. Remember the KLM flight didn't crash, even though all four engines were initially knocked out after hitting a volcanic dust trail. The plume was from a volcano they had not been told had exploded - otherwise they would have flown around it. The conditions under which airlines would fly today are not comparable to that historic incident as there is much more weather data available to guide pilots.

Isn't that the point though? Surely KLM isn't asking to fly directly through a plume, but perhaps the powers that be can be more flexible... instead of a blanket ban recognise dust-free windows exist where flying safely is possible. Remember this is not just geology and meteorology here but economics - 30-40% of trade is by air - and politics - who decided on the blanket no-fly-zone? I think KLM have proved the need of greater flexibility. There's a window of opportunity midday tomorrow where people can be flown home to UK.

KLM has been up there flying. Met Office has a computer model. I'm not sure who to trust.

In the summer we often get plumes of sand from the Sahara deposited on our cars. How is this ey-a-loke volcano ash different from regular sand deposits? Perhaps the international rules are too inflexible and do not take account of local variability where it is possible to fly.

Thanks for that!

cloud has swept across in front of the volanco.

Is there a good site to look at satellite images of the dust cloud?

7.7C