First time poster, long time reader here. I'm a Geologist with a life-long fascination with flight. Thought I'd post a note on the geology side after reading posts above by flying lid and carjockey.
Agree that the details matter a lot when evaluating risk. Volcanoes eject all sorts of mineral matter, not just silica, and each of these mineral types have greatly varying properties such as hardness, melting points, etc.. And in the case of jet engines I would think "size matters" could apply, although an engineer should be consulted. Even if 100% silica (volcanic glass) the size of the particles/exposure time to engine heat might dictate level of damage to an engine. Sufficent sampling should be conducted and analysis done before jumping to conclusions.
As to the history of this region's vulcanism - we do have some decent records. Based on those, if history repeats itself things could get worse, maybe much worse, before they get better ----
"..... as Science Fair noted, the Eyjafjallajokull volcano isn't necessarily the main problem. It's Katla, Iceland's noisier neighbor, that's the concern. If lava flowing from Eyjafjallajokull melts the glaciers that hold down the top of Katla, then Katla could blow its top, pumping gigantic amounts of ash into the atmosphere."

Unfortunately there seems to be correlation between the small eruptions and awakening of the big brother in the past, so cross your fingers that history doesn't repeat itself. No mention of poisonous gases in this particular article, but I've seen multiple other posts that mention deaths from gas in Britain. There's tons of data available for the Googling for those interested in more details.

Greatly enjoy reading your website - thanks. :)

It's real
 

I was a bit of a sceptic, but a German Air Force flight (GAF949 at 350 )heading east over Northern France just been told to take avoiding action to miss a reported ash cloud, about 45Deg to the right. So it must be real ?

CJ,

Totally agree with you - safety is and always should be paramount. Although with regard to damage we do have some idea from the BA009 incident of 1982 which you alluded to, namely sandblasting, turbine damage, etc.

I disagreed with your point re temperatures (as per Lompaseos post) as the temperature, and the type of ash, does have a very real effect due to the ash being able to melt and then re solidify.

I agreed with your point about sandblasting but stupidly (and rather embarrassingly) didn't think through my post before typing - my mistake, and I apologise.

It's been a very interesting day today and at the minute I'm not sure we'll be flying tomorrow yet either, but we cannot rush this. For all the stranded PAX I feel very sorry, for all the airlines losing money and handing money back, I also feel very sorry - this couldn't have come at a worse time for the industry, and I hope ALL operators survive this.

DW.

G-FBFI = G-CHAI CL601-3R Challenger 5152 OXFORD to BIGGIN

Several others into FAB 2 CHOPPERS 1 F7X (HB-JSS) +(G-SIRS)
VFR below airways

TONY

Basis for decision making
 

S76 Heavy

It isn't just a random decision

ERUPTION OF EYJAFJALLA VOLCANO IN ICELAND – ICAO SYSTEM EFFECTIVE IN ENSURING THE SAFETY OF AIR TRANSPORT ICAO News Centre

Keep an eye on Katlia, that is the real danger.
 

The Katla volcano has a reputation as one of the most dangerous volcanoes in Iceland, and it has exploded in the past just shortly after the activity of the closeby one that is causing all the mess now.
Katla has been showing signs of unrest since 1999 and geologists have concerns that it might erupt in the near future. Particularly, monitoring has been intensified following the March 2010 eruption of the volcano beneath the Eyjafjallajökull glacier. The eruption of this nearby long-dormant volcano in March and April 2010 prompted fears among some geophysicists that it might trigger an eruption at Katla.
Katlia could cause enormous disruption for very long period of times, even years. The ash cloud of today would be a joke compared to the cloud that Katlia could generate over all Europe and beyond.
Unfortunately nobody can stop this incredible force of nature.:ok:
A good reminder to us all, spoiled humans.:ugh:

S..Heavy,

Maybe the so called over reaction to the flu epidemic worked and prevented it from spreading.

If in doubt, there's no doubt.

Just because you are not involved in the debate does not mean it is not happening. I got 3 hours sleep last night because I was busy trying to provide the relevant people with high quality data regarding the ash. I've spent all day today dealing with calls and emails from scientists wanting information about how well some satellite sensors that I worked on can detect the ash. There is plenty of debate about it, and this debate will continue.

So you'd rather that the NAT etc close the stable door after the horse has bolted?
Frankly that is a reckless and dangerous attitude to take. Do you need an accident to happen just to prove that this ash is a problem?

Are we talking hours, days or weeks? No idea really.

I assume UK is particularly prone to be effected badly - in an event like this (meteo combined with the eruption) due to our relatively small size, and how close the airports are together ?

presumably in larger countries there are more possibilities to divert around ? and or divert to other airports a bit further away.

Hi res, very large image from NASA:

http://www.nasa.gov/images/content/4...o-20100615.jpg

As someone who has to sit in the ash at 36,000 feet daily my partner and children are perhaps thankful for the so called prudence and wisdom of those who have more data at their finger tips than most of us on here. If there has been an over reaction ask yourself why ? The litigious society we live in ! Imagine a flame out nowadays, everyone survives but they all sue the airline for post traumatic stress, they sue NATS in fact the passengers sue everyone they can as they now have video footage in the cabin of their trauma ?

So we all sit on the ground for 4 days, nothing happens, no one falls out of the sky that is a successful outcome surely? When you wait for a thunderstorm to pass the end of an airport does it need a jet to fall out of the sky due to a windshear encounter to justify your decision ? Nope its a duty of care that all professionals exercise when they have more data in front of them.

Do we need a jet to fall out of the sky to justify a correct decision ?

Final point, Chemist friend described the difference between volcanic dust and sand dust, sand dust is like the rock in your garden the volcanic has a rough jagged serated edge hence the windscreen damage. Discretion today is the greater part of valour.... Fly safe mon amie

Sand under microscope

Volcanic dust under microscope

Volcanic dust is vastly more abrasive than sand. It has very sharp fresh edges and can be fine enough to penetrate very deeply. It can cause severe lung damage if inhaled.

Having clarified that, I'm with those who strongly suspect a degree of over-reaction here: for instance I can't help wonder how much risk there would be heading southbound out of LGW or LHR.

I don't know that much about volcanoes, but there is very little information available to Joe Public which indicates that the ash cloud would be a danger. Yes, there's a plume around the Shetlands, but Joe Public living in London who wants to fly from Gatwick to Spain can't see how that affects him.

Presumably some people reading this thread have access to rather more information than is publicly available. If so, could they consider making it available to Joe Public, or do a better job than just saying 'When Eric Moody....'
London is 1,000 miles away from the volcano - so any ash dispersal is likely to be at a relatively steady pace dependent on the wind and presumably moderately predictable based on meteorological forecast, rather than relatively unobservable underground geological events causing the volcano to suddenly increase its activity

I can't see any national security reason as to why information on the extent of the ash or volcanic gas should not be public. Show people the scientific evidence and they'll stop saying it's an over-reaction

Updating for Paris
 

Some informations from Iceland MET office indicate that the eruption is increasing in intensity.

LFPG/LFPO/PB closed 15/2100 16/0800z.

BREST FIR/UAC closed North of 47 North. 46 and 47 N open for Eastbound. 48N and northern closed.

EHAM closed until 0800z

Regarding the doubt on the density and risk of this ash cloud. Quite possibly the only way to find out will be to fly through it.

So the question to the doubters, would you ask a crew to fly through it knowing that they may be risking a total engine loss and the possible subsequent consequences?

As one of those who has to sit in the ash cloud...or not! I'd greatly appreciate more info/debate on the risk assessment process which has led to this decision. The situation has repeatedly been described as "unprecedented". It isn't. There are active volcanoes all over the place and we work round them. What is so much worse about this one?

A massive over-reaction. I'm 25 miles from LHR and looking at a lovely clear sky. Not a particle of ash in sight. Please don't tell me that it's the invisible ones that do the most damage.

west lakes - I certainly wouldn't ask anyone to risk their life over it.

However, is there really nothing that using one or more of weather balloons, unmanned drone, or satellite that could provide information on ash density ?

Even if the investigation costs 10 million pounds per day, that's still peanuts compared to the cost to the UK economy

I agree it is prudent to close airspace to IFR high level traffic. I would be interested to see how HIA ( Highlands & Islands Airports) justify sending all staff home and closing the airports. We tried to fly our Islanders out of KOI VFR to be told no. :ugh: