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BeechNut

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Has anybody bothered to study the similarities between the eruption of Mt St Helens in 1980 in N.America? Google isn't turning much up on the subject

Although the visible plume was well defined, the ash from Mt St Helens reached the US east coast in three days and spread around the world in fifteen days. There are plenty of referenced to this, such as Keep Your Eye On Mt. St. Helens' Ash, Alaska Science Forum
At the time, maps were available showing the location of the visible plume, and we planned around this area.

In 1991, the ash from Mt Pinatubo extended around the globe, and is often credited with reducing world temperatures. Once again, aircraft were warned of the location of the visible plume, and avoided it. There were some spectacular sunsets that year.

When Mt Redoubt erupted in 1989/90, we continued operating into Anchorage (daylight only), visually avoiding the plume. This often meant a longer route in, due to the closeness of Mt Redoubt to Anchorage.

If there are any engineers who were around at the time then perhaps they could comment as to whether there was any damage to the aircraft during these times.

Perhaps it's time for the engine manufacturers to determine if there is a safe level of ash. Do we know how the present level compares with past eruptions?

Dave

Predicted IFSD rates are not expected to rise because of ash ingestion as it would only be an minute contribution among all the various causes.

Futhermore ETOPS is predicated on independendant en-route failures and not on common cause which affects more than twin engine aircraft.

The safety related effects of ash are developed in minutes and immediately obvious (cabin lights go out etc.). The longer term effects are discernible over many flights as deteoration of performance and addressed by maintainence between flights.

I can't understand why posters are making this doom and gloom stuff up rather than leaving it to operators and OEMs to sort out.

"A spokesman for KLM said: 'We have not found anything unusual and no irregularities, which indicates the atmosphere is clean and safe to fly.' " That seems very broad.

I spoke to a Parachute Pilot in Ireland today who said that whilst they flew there was a visible layer of ash and also a strong sulphur smell in the air. Its a small operation and they were able to file VFR as it was truely VFR conditions. He said you could see nothing from the ground but once you got up to 9000ft it was very obvious as was the smell. The skydivers reported being able to smell and feel it in freefall.

Im wondering what happens if only a handful of airspaces open up , does it
signifigantly alter the picture. The cost to us in business terms is terrible and soon our own company has no choice but to lay people off as already things were so tight with the non volcano recession.

The logic in the points being made is that Tin may not start falling out of the sky if it encounters ash straight away and this seems plausible but I have a very bad feeling for the economy and aviation sector if for example flights stop and start based on local conditions and wear becomes a factor. I suspect that when flights start a lot more inspection procedures will become the norm increasing costs to pacify a public who have been led to believe that aviation is very dangerous so long as there is " ash " in the air. It is kind of obvious too as there is " dithering " over what is a safe level.

I suspect also a large problem now will be a legal one with insurance companies looking to cover there rear , engine manufacturers looking to cover their rears etc. I hope I am wrong but suspect and fear this is going to get messy with nobody wanting to take responsibility for saying it is " safe ". Meanwhile the non commercial tests being conducted by G- CALM continue to point out that they do not feel its safe.

Somebody posted Continental had suspended all Northern European flights until the end of the month, I cant find that anywhere on their website.

TCX have aan A330 coming full of pax from Cancun into Alicante tomorrow.

South and Central Spain are not closed , never have been to my (local) knowledge.

Obviously.

The plane is full of english passengers, which will then be brought back to the UK by land/sea etc.

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Originally Posted by lomapaseo (Post 5643829)

Predicted IFSD rates are not expected to rise because of ash ingestion as it would only be an minute contribution among all the various causes.

They may not be expected to rise - but aren't ETOPS certifications based on documented actual IFSD rates achieved by certain operators under standard conditions? It remains to be seen whether rates will change after fleets have spent a week or two operating in the ash environment.

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Originally Posted by lomapaseo (Post 5643829)

Futhermore ETOPS is predicated on independendant en-route failures and not on common cause which affects more than twin engine aircraft.

Indeed - but the point I was trying to make was that if operating engines in an ash environment for a period of weeks compromises future reliability - then the probability of two independent en-route failures during future ETOPS is increased.

Let me put it this way - this summer you have an IFSD during ETOPS. How comfortable will you be with the fact that your one remaining engine spent a week or two operating in an ash environment?

I am staring at a GE First stage turbine blade as I write this. It has dozens of holes in it that channel cooling air through it. The holes are about .25 mm or less in diameter. They are also angled and profiled.

This blade operates in a gas stream that is around 300C hotter than its melting point.

If the cooling system fails due to clogging with molten ash, damage will be immediate, severe and very very expensive.

Please understand that the airlines are currently between a rock and a hard place until they can satisfy themselves that they can fly without wrecking their very expensive equipment.

They can fly, earn revenue, then bust the equipment and lose revenue as well as suffer repair expense, or they can lose revenue until it is determined that there is no hazard, or that the risk is manageable.

At present no one to my knowledge knows enough to satisfy themselves that the risk is manageable. Failure to manage that risk could involve loss of life or grounding a large chunk of the fleet in the coming weeks/months due to lack of engines.

http://
http://www.metoffice.gov.uk/aviation...1271634757.png

Looks like all new cloud caps out at FL200....?
Definitely looks "friendlier" than previous forecasts..

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I am staring at a GE First stage turbine blade as I write this.

Good to hear from someone that is not a meteorologist or vulcanologist (or politician) on the possible effects. For once some relatively sane observations between the "Don't fly it's risky" and the "To hell with it, let's go" :ok:

My only point so far is that the decision should be left to those best able to make them:
1. Airlines
2. Insurance firms
3. Pilots (w butt at risk)
4. PAX (idem)

Having zee Govt making the calls means vanilla for all, wether you like it or not.:ugh:

Watch Air Traffic - LIVE! - We said cash, not ash!

Aeroflot AFL315 is flying from Moscow to JFK via PORTO Portugal right now

Hows that for a re route

As a very small example of the thought process that is probably now evident in the minds of 'the authorities', the Blackwall Tunnel (A102M) in East London is, I think, instructive.

At one time, a couple of years ago, the two Lanes of traffic through the northbound 'old bore' were supplemented during the morning rush hours by one lane of the southbound 'new bore'. Diverting gates and lane closure lights emphasised local custom and it was a system that worked pretty well, allowing almost half as much traffic again, to flow through the tunnel. Once the peak morning period was over, the lights changed and the southbound bore reverted to two lane for the rest of the day.

For a reason best known to himself, but most Londoners suspect it was part of his agenda to shutdown private traffic in London entirely, Ken Livingstone - the Mayor - suddenly stopped the morning contraflow scheme. It was said that this was 'for safety reasons'. Now most Londoners had been completely unaware of frequent - or indeed any contraflow related accidents. This added 40 minutes to the average transit through the tunnel, making it about an hour and a quarter or more, to travel a couple of miles and cross the river Thames.

When Boris Johnson was elected mayor, he commissioned a review of the Blackwall tunnel situation and found, to no-ones great surprise, that the effects on accidents was negligable, but the effect on congestion was unacceptable. So he ordered that the contraflow scheme be reinstated.

However ........... the HSE said, 'oh wait, if we start the contraflow and there is an accident after all this time not doing it, then it will be our fault. So we cannot agree to opening it.' And there it rests, a perfectly good system for reducing congestion cannot be used because, basically, nobody wants to take the responsibility for saying it can.

As I said, a bit off thread, but you can probably see where I was going with it.

Roger.

Jetstream forecast

Here's a forecast summary for the week coming up. Interestingly, this article states most of the ash is 10000 feet and below. Maybe more ash over UK/Germany midweek but in a narrower band. Southwesterly to kick in late week and take the ash away from Europe.

A respite until the next northwesterly flow sets in?

AccuWeather.com - Weather News | Ash Plume to Shift Farther South through Europe

Best,
Jim

"Over in the US, Continental have announced today that they don't expect to resume flights to Europe this month!"
I heard that this afternoon on FoxNews, found it rather odd. What do they think they know that we don't - hiring psychics now ?

"It must be getting serious, the yanks are even covering it on the TV now."
Believe it or not, some of us here in the colonieshave been following it from the get-go, but more as a curiousity of nature. :}

Landroger...

nail...head...hit...

Good analogy.

The entire situation has been receiving quite a bit of attention over here in the States. There are plenty of pax stranded in North America as well.

new NATS release

NO change on restrictions - still 7pm. First time they hadn't extended it....

Conditions around the movement of the layers of the volcanic ash cloud over the UK remain dynamic. NATS is maintaining close dialogue with the Met Office and with the UK's safety regulator, the CAA, in respect of the international civil aviation policy we follow in applying restrictions to use of airspace. We are currently awaiting CAA guidance

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At present no one to my knowledge knows enough to satisfy themselves that the risk is manageable. Failure to manage that risk could involve loss of life or grounding a large chunk of the fleet in the coming weeks/months due to lack of engines.

Of course we do, it just takes a little time and data to sort it out to the satisfaction of the operators and the authorities.

The risk managers define the data necessary and the authorities examine the numbers to ensure that they do not appreciably increase risk compared to the normal base risk that is carried in day to day operations. No doubt it may take some extra precautions for the time period that the risk of encounter is raised (operation downstream of an eruption) as well as increased maintainence actions between flights.

Let me start by saying that I'm SLF, not a pilot and I'm also not a geologist. However, I have a friend who IS a geologist and one that specialises in volcanoes. A couple of us asked her about why THIS eruption is causing such a problem and also about the prospects for the future. Her reply might be of interest here:

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To answer your question, It ALL depends on the type of magma that is erupting - how viscous it is and how much there is going to be erupted. The volcano /could/ - it has before - erupt for up to two years or more. If the magma is basaltic then yes, pretty much as soon as it runs out of water it will go from phreatoplinian style (phreato indicating the presence of water, plinian being the eruption type - see pic below - it's v. recent) back to the effusive Hawaiian lava fountain type that was happening last month - it's a bit like pouring water on a chip pan fire (which I can tell you from seeing this done in controlled conditions is a /most/ impressive fireball). Samples collected last month and analysed suggested that the lava being erupted was a alkali-olivine basalt, with a silica content
of about 47% (silica being the thing that makes a lava all sticky and gooey and therefore more difficult for gas to escape). So it was all fairly fluid and gas trapped in the lava could easily escape. So far as that goes it would cause relatively few problems once the glacier had melted (10-15% of this has already gone according to my sources.)

However, the ice isn't really a massive problem in the long term especially if the lava IS still the same composition because once the ice has gone the eruption will settle down - locally however it could (and has) caused MASSIVE damage from jokulhlaup (meltwater floods). Roads, infrastructure, and farmlands have all been destroyed but so far there have been no fatalities as people had been evacuated from hazardous areas. Iceland being prepared for these eventualities.

It is currently erupting from a series of vents along a 2 km long north-south oriented fissure, with meltwater flowing down northern slopes of the volcano, but also to the south. The eruption has been fairly steady throughout this phase and will continue to be so for days at the least. Chemical analyses of the ash samples from this phase of the eruption however reveal fluorine rich intermediate eruptive products with silica contents of 58% (a more sticky magma than that erupting earlier) so it has evolved from the initial lava producing phase of the eruptive activity possibly by crystal fractionation in the magma chamber.

The eruption at Eyjafjallajokull is however still going strong with frequent regular cycles of steaming and phreatomagmatic explosions. The Icelandic Met Office is heading up to the volcano to conduct a survey of the crater area to find out (1) what it looks like and (2) how much new water (i.e., ice) is there available for the erupting magma. More water is likely to mean more explosive eruptions in this phreatoplinian style - however, like I mentioned earlier, the bulk andesitic composition of the ash implies it might have a decent ability to produce explosive eruptions without a lot of extra water (but it helps). You can see a great sequence of images from the eruption on this video (although the music might not be the most fitting). It shows the "puffing" nature of the eruption, which might imply periods of melt water getting into the conduit and flashing to steam (very loosely like a geyser behaves). The Icelandic Met Office has excellent information on the ash and the flooding, which has been somewhat forgotten in the news. There has been extensive flooding around the volcano due to the melting ice.

SO FAR there is little or no evidence that Eyjafjallajokull erupting is affecting her big sister Katla (who can cause far bigger eruptions) and is likewise sitting under an ice cap.
Eyjafjallajokull could keep erupting like this for months. It may not. It depends on many factors. We just have to wait and see (and pray Katla doesn't get set off - she is overdue for an eruption)

The weather patterns certainly aren't helping either so it really is a combination of things.

I haven't bothered recreating the links she posted, mainly because they're ones I've already seen in PPRuNe.

However, what seems to come out of this is that the particular combination of Magma erupting under a glacier is why this is creating "the wrong type of ash" and causing the problems we are seeing. My friend's post also explains why it it misleading to assume that, because a previous volcano did or didn't cause problems, there is a precedent in this case. This eruption is a particular combination of circumstances--I quite like the analogy to pouring water on a chip pan fire--and I, for one, am happy to leave the decision about when it is safe to fly to the experts.

Hope this is of use.

Bob