Right. I made an algebraic error. 32 g is it.

You can easily adapt to different times and conditions.

Well, yes and no. ICAO EUR Doc 019, if that is what you are referring to, comprises guidance and recommendations for various bodies to follow if a volcano blows in the N Atlantic area, but is a very long way from being law in England and Wales or anywhere else in the UK.

Any other ICAO document would have a similar status.

IF the person or organisation who decided on the airspace restrictions got it wrong, or was not even empowered to do that in law even though he/she/it obviously can in practice, repeat IF, then that's where the airline lawyers will aim.

Reason? Don't be naive; money, and lots of it, in compensation at taxpayer expense.

From a political perspective this is all further proof that the lunatics are running the asylum.

Management is doing "things right", leadership is doing the "right thing".

If we had leaders with any backbone they would have the moral courage to open the airspace, albeit with some restrictions. Having those BA aircraft diverting away from LHR is utter nonsense.

What's the problem ???
 

David Learmount, on Flightglobal (q.v.) rightly says that "the" problem is twofold:
1) A volcano in Iceland is erupting vioently
2) A very stable High-pressure system is unusually far North and directing the plume south-eastwards.
#2 is unusual for this time of year.
This is an unprecedented situation, which is why none of the "risk assessment" or researchers have predicted it (for all their Ph(u)Ds from Llaregub U).
Because of the above, engine manufacturers have not spent time and money collecting samlpes of volcanic ash to throw at engines on test-beds (And probably won't in the future, for cost/benefit reasons, which is sensible).

OK, it causes chaos and hardship for passengers (and airlines), which insurance companies will no doubt still be disputing in years to come.
The situation will ease when the weather pattern changes - maybe a Low will send the stuff from this and any bigger bang northwards, over the Pole and into Nothern Canada or even Alaska - then what will Sarah Palin say ???


N.B. Tongue ever so slightly in cheek at times ...

Oh, but airline industry is conducting such a research on an Europeanwide basis right now. If things go pear shaped, at least historical LIDAR, wx baloons and research aircraft data will show what was the concentration that stopped the fun. If not we'll know what's the safe level.

I did participate in a "test" flight today, albeit on the fringes of the VA propagation forecast (as forecast by the Met Office, not Eurocontrol) and therefore I would be only too happy to wake up and discover that Finnish Hornet story was hoax, that data from Friday's met flight in UK are secret to hide the fact that closing the aerospace was overreaction and that avoiding VA by using Mk1 eyeball guarantees long and happy engine life.

What are my chances of waking up fat, dumb and happy?

Poor to nil, I'd estimate.

Parts per million
 

Just been trying to get a feeling for "parts per million" as this is discussed a lot on this thread - and what is apparently being measured.

1 part per million - by weight, what is it?

Well, the weight of the atmosphere causes pressure, and sea level pressure is about 1,000hPa = 100,000N/m2 so that means about 10tons of air above each square metre. (That makes sense because 1m3 of dry air weighs about 1.2kg at sea level, so without allowing for declining pressure, thats 8,000m - so if the air spreads up to 20-30km before "fading out" that makes sense). Thats 10million tons above each square kilometre.

The weight of air above the UK, surface area, 250,000km2 must therefore be 10million times 0.25million tons = 2.5 trillion tons. (2.5 thousand billion tons)

So, if the ash were 1 part per million, and were spread uniformly throughout the air above the UK, the ash in the UK air would weigh 2.5 million tons.


Similarly the whole of Europe is 10million km2, 40X UK so there is about 100trillion tons of air above Europe. 1ppm would be 100 million tons.

Some other points:

1 ton per second of ash generation means a million tons every 12 days

The first three days of the eruption on 14 April 2010 at Eyjafjallajökull. generated about 750 tonnes / second on average - so thats about 200 million tons errupted in total so far

If spread uniformly over (just) europe that would be 2ppm

Obviously its not spread uniformly, has also spread over the atlantic and russia.

Can anybody provide a number for the mass of air passing through a typical (e.g. A320) jet engine per hour of flight?

If anything is a display of backbone it's the fact that in the UK the restrictions still stand while the rest of Europe is out flying. I should say that somebody IS demonstrating moral courage, and a proper respect for safety.

Less ash, more lava: Eyjafjallajökull changing its style?
 

From a Volcanologists blog, a ray of hope maybe ?


Less ash, more lava: Eyjafjallajökull changing its style? The Volcanism Blog

Or the opposite view is saving face and trying not to get sued! My guess is we will be flying by Friday or Saturday, until the wind changes that is and then we will either have a different kind of ash or we will be using option 2 or 3 of the EASA plan. We are currently on option 1 according to the information being published by my company. So I am hopeful we will see sense returning to the situation shortly.

BBC News - Ash ban to remain for most of UK
Leaving aside the arguments about wise caution/over caution, what do we think the plans are for a decompression descent? OK, not probable but caution is still caution.

@ Tyres ... valuable input. There was always the hope that the eruption process would change; perhaps this is the "end of the beginning"?

@ Spotters various ... thank you for your inputs gleaned from the spotters websites. :ugh:

Having read every page of this thread over the last six days (up to page 99 which is when I started typing this offering) it is clear that there is a wide variety of argument and counter argument, much of it centering around conjecture.

Having been trained in the industry as an engineer 50 years ago! (though I never "practised) and as a PPL of 20 years, from what I can deduce there are some things we know, some we don't know and some which we ought to know for future episodes of a similar nature.
In summary I think these include -

What we know -
1 A volcano erupted and due to the high inflow of glacial meltwater it's output consisted of high level of fine particulate ash which is relatively unusual.

2 An unseasonal slow moving high over the UK caused a southerly flow which caused the plume to move south before splitting and moving both east and west. This dispersal pattern is generated by computer models rather than direct empirical observation.

3 Volcanic ash (VA) with high levels of silica CAN cause severe problems both short and longer term to jet engines, both immediately suppressing combustion and damaging turbine blades.

4 An ICAO "directive" or advisory, issued after a major emergency in 1982 laid down "rules" to be followed in the event of VA clouds impinging on airspace.

5 The subsequent shutdown of UK and European airspace has caused economic damage to the industry, other industries, national economies and considerable discomfort and worse to large numbers of passengers.

6 A small number - very limited - of "research flights" have launched in the later stages of this situation and the results, if clear, have not been widely published.

7 Airframe, engine manufacturers, operators and national and international regulators have failed to undertake or insist upon research which would increase knowledge on which to base actions regarding such situations.

What we don't know -
1 The degree of accuracy of the models and therefore the actual dispersal of dust, either laterally or vertically, and there is little information as to the vertical thickness of layers.

2 Precise data about particulate size, or chemical composition once the dust has reached altitude, and even if we did -

3 There appear to be few if any advisories from engine manufacturers as to the chemical composition of dust, the particulate size, or the density of cloud (ie likely throughput) which engines can "tolerate" without damage, or continue to operate in while maintaining power while suffering damage.

There are many, many more knowns and unknowns but these seem to be the key ones.

Therefore given that the regulators and "safety authorities" do not know what's going on, or what is a safe situation in the first place it is entirely predictable that they will take the NIL RISK route, assuming the worst case scenario and avoiding it by putting aircraft on the ground.

Far more important than what is happening at the moment is what WILL happen in the coming months. The industry must undertake detailed research to find out what its equipment will "tolerate", while national and international authorities MUST put in place systems to ensure that any computer models of future events can be checked in detail by actual sampling to ensure that a vital industry is operated on the basis of knowledge rather than computer guesstimation.

Had such work been done on a regular basis since 1982, we would have 28 years worth of useful information instead of very little.

Until that happens I suspect that the authorities will insist that we sit this out until it goes away…..

BA124 nearly made it to LHR but is presently turning back to AMS (now looks like Brussels)

This is not a spotters post. I'm wondering why it is safe to land at Brussels but it's not safe to land at Heathrow? The weather is the same at both, and they are both in the Met Office 'ash cloud'.

After reading much of this thread, along with some other research, I can only conclude that it's going to be difficult to define a "safe" concentration.

Any outpourings from a volcano, encountered by a turbine powered aircraft, are likely to pose some sort of long term risk.

From: http://www.caa.co.uk/docs/375/fsd_may93_p1-9.pdfFrom: http://www.nasa.gov/centers/dryden/p...ain_H-2511.pdf(Interesting photos on page 1).

Sounds like flying in any aeroplane that has ever been flown through volcanic ash and/or gas is going to be less safe than one that has not.

I realise that most things in life involve risk assessments - I'm just glad I'm not the one with the responsibility of making the decisions here. I think it may be a little unfair to be slating people for taking the safe(r) route of maintaining the airspace suspensions.

Just my point of view.

OC619

This is beginning to look like the blind leading the blind leading the blind.

If you study the six-hourly actual/predicted 'ash cloud' source map data from the London VAAC that is being published by the Met Office and allegedly being used by NATS to make its UK Controlled Airspace open/closed decisions, you can see from the predicted data yesterday exactly why they chose to open the Scottish FIR and nearby regions, albeit temporarily, today. However, the maps are all clearly marked "ASH CONCENTRATIONS UNKNOWN".

If the ash concentrations are unknown then how is it possible to define the edge of the contaminated area where presumably the ash concentration has supposedly fallen to some identifiably small but as stated "UNKNOWN" level in the first place? What is that level and how does the VAAC even know where to draw the line?

Further, this apparently unknown concentration region of ash extends throughout most of Europe where flying has been permitted today.

NATS is clearly basing its fly/no fly decisions precisely on these maps and the livelihoods of large numbers of people around the world are being substantially impacted by this extremely ill-defined and completely misleading information.

Someone needs to be brave enough to step up and stop this madness. Everyone is hiding behind data produced by a group of well-meaning technical staff at the London VAAC but not being prepared to make a common sense decision as the stakes of making that call are astronomically high if wrong!

It does appear that the Europeans have been prepared to stick their necks out well before our politicians/bureaucrats have.

Is UK signed up to ICAO? Yes. Is part of NATS licence to comply with ICAO etc? Yes.
Very big if and given that NATS has complied precisely within the terms and conditions of it's licence they're squeaky clean (and I do believe I've said this previously).
Compensation for what, following the guidance and recommendations of one of the governing bodies for Aviation? I would very firmly put the boot on the other foot and state that NATS should be prosecuted if it had FAILED to follow the ICAO guidance and recommendations.

BD

Those BA planes could be getting re-routed to Shannon Ireland. Some info here from the irish aviation authority:

Irish Aviation Authority - UPDATE ON AIRSPACE RESTRICTIONS

Looks like im going to be stuck in Paris until the end of the week.

there are too many unprofessional people out there. Nobody knows how to deal with a crisis and everybody just act to protect themself, not in the name of the safety of flight, but in the name of the "law" wich is far away from the environment we're all working in. no common sense:=:confused:

Perception of and attitudes to risk management I guess. What I still don't understand is why flights were allowed into Luton this afternoon, but none were allowed into LHR.

Anyone know why the flights from Canada to Luton were cleared through closed airspace ?

80/-

Colleague heard from a Klm pilot on his freq that KLM policy is that they are only allowed fly IFR in VMC conditions ??????..... seeing as they were the ones shouting about how safe it was to fly......why this policy????