Your argument is based on an assumption that airlines are too stupid to recognise this, and therefore need civil servants to tell them what they can and cannot do.

NASA has posted an example of satellite and lidar observation of ash clouds for 16 May.

As NASA puts it

Nighttime Ash Tracking with CALIPSO : Image of the Day

The civil servants are did what the airlines and manufacturers told them to do they set the standards. They modified them quick enough when it started costing money.

John

This appears to be the biggest problem we have with the current methods of determing ash in the atmoshere.

If its dense it can be seen both by the pilot and by satellites. Setting any very low acceptable ash levels is going to cause a major problem of locating where they are by the simple fact that they cannot be seen.

As such we rely on computer and mathematical modelling which may hold X ash concentrations but may also hold X+Y or X-Y or infact no X at all.

Without analysing millions of test shots of air over huge areas we dont know.

Maybe the best way would be to scrap the minimal acceptable levels altogether and to use the satellite visible charts with a safety area around those visible dense ash concentrations.

On the basis that if you cannot see it its unlikely to hurt you aircraft flying in the computer generated low ash areas which are not visible and where ash may or may not be present should be monitored on a more regular basis until we do know more? but with NO meaningless limits

Pace

I think Sunfish's argument is based on the fact that airlines sometimes do things which are not necessarily optimal for safety, for a number of reasons (in order to maintain market share, when everyone else is doing it, for example). It is appropriate for a regulator to step in when it judges that that is happening.

Indeed, that is still one of the most frequent comments about U.S. airline deregulation, that safety has suffered as a consequence (that is not necessarily my view; I am merely pointing out that some hold it).

In the current situation, it would be very hard for an airline not to fly, even if it judges that it is not wise to do so, if everyone else is flying. The airline would instantly lose all market share.

PBL

What like flying in areas of thunderstorm activity, like flying approaches and departures with surface winds above 0, like flying in the bird migration seasons or into and out of coastal based airports etc etc etc :ugh:

Safety has to be based on a demonstrable threat there is no demonstrable threat from a light ash encounter only a percieved possible threat. There may be ??? a financial cost threat but as yet not even that is bearing up to scrutiny.

Pace

Oh dear..... misinterpretation and sometimes misrepresentation are a bit of a safety hazard around here!

I NEVER suggested that any UAVs should fly in or near air routes.

If you want to run the line that UAVs will never be allowed in 'civil airspace' without defining what exactly you mean by that: ie. any bit of sky not specifically defined as 'military'? or what? Noting for a moment that Predators based at Bagram MUST pass over, under or through some 'civil' airspace in Afghanistan to get to where they need to go.....

I've no idea how this actually gets regulated inpractice but a knee-jerk 'Never until rules submitted in triplicate and signed off by God (or at least the Pope)' won't ever be helpful. I guess it depends what your 'medium term' is. But I assume you don't mean 'a month or two'. Believe me, if UK National Security was truly an issue and UAVs were the correct response, they would be whizzing round your ears by next week! I was tempted to add 'Get over it' but somehow resisted!

Appreciate your knowledge on turbine blades, do you know how many there are on a Piper, or a microlight, or a glider ? Those folks running the regulator probably don't - in fact some are on record as stating "‘I know nothing about aeroplanes".

But you know, don't you ? So you must know what the other unspoken risk of VA is that grounded all these aircraft along with the jets ?

"measured" ? "proportionate" ? More like knee-jerk, incompetent, a**e covering. (unless you can enlighten us as to the VA risk to gliders ?).


<begin rant>
And as to the "minimised disruption" - you are having a laugh.

The regulators and governments meanwhile did absolutely **** all to help for several days until shamed into action by the media. Even then it was pathetic - over a week IIRC to get five or so coaches out of Madrid and a navy ship that they decided could take a whole 250 people from Santander (until the commander probably torpedoed the rest of his career by taking more). Tour operators were moving convoys of 30 coaches at a time inside a couple of days, and chartering ships for 2000 pax at a time.

Politicians talked out of one orifice about "dunkirk spirit" whilst effectively ordering the closing the channel ports to small boats trying to get people across (can't cross the channel on small private boats these days apparently - watch out GA, you'll be next). Immigration staff (presumably idle) at airports were not deployed to sea ports, resulting in queues hours long and broken onward transport arrangements. UK immigration at Calais was so well organised that our coach was sent through it twice (while ferry staff were counting down the minutes to departure).

"minimised disruption" ? Actively hindered anyone elses attempts to do so is more like it.

The whole affair was a classic example of our overstuffed EU/UK bureaucracy which has no plan, no clue, and no ability to respond other than by getting in the way.

<end rant>

Entertaining rant but you're wrong about the EU. Initially they had no mandate to get involved, when they stepped in over the first weekend to clear up the mess that the national authorities were making of it (and a lot of highly placed bureaucrats racked up a lot of weekend overtime) things started to happen with some rapidity.

The British Health and Safety disease.

Belt, braces, AND DON"T STAND UP !:=

Infrequent:

You may have a point about piston engined aircraft and gliders. Last time I looked, the Piper I fly had an airfilter, but hey! the aircraft is hired so what do I care anyway? A little ash exposure might help the rings seal and save me a honing job.

When I studied risk management as an engineer and later when I had to apply it in an airline engineering department, we worked on facts. In the absence of facts regarding the likelihood of exposure to some quantity of ash by large numbers of aircraft, the regulator acted promptly and grounded the fleet until the available facts could be marshalled and discussed by people with the relevant expertise and experience. They did this promptly, efficiently and responsibly in a matter of weeks.

The fact that the regulators response didn't suit some of you is irrelevant.

As for comments about "commercial considerations" and individual airline decision making those are also way off the mark. Aircraft Insurance contracts and lease agreements would most definitely preclude doing anything not approved by a regulator, which is probably why Ryanair so promptly grounded its fleet in my opinion.

To put it another way: You would all be screaming about why the regulator didn't ground aircraft if half the fleet was now ash damaged and out of action for months.

I'd like to offer an analogy to VA that I think is illuminating, because there are similarities. That analogy is SLD (Supercooled Liquid Water Droplets).

Unlike VA, SLD has been linked to actual hull losses.
Similarly to VA, there are NO accepted criteria for SLD.
The only advice any OEM gives anyone regarding SLD is the same as that for VA a month ago - avoid at all costs.
There is no reliable means today for detecting SLD, or VA, onboard an aircraft. In certain circumstances visual detection of either may be possible, but is assured in neither case.
Our ability to reliable predict SLD or VA is, in a word, unreliable, in both cases normally for lack of accurate data about the atmosphere.

To date the situation with SLD constitutes a (barely) acceptable risk - although it's been an issue of contention between FAA and NTSB for years. Industry and the regulators have been trying to come up with workable means to handle SLD since Roselawn, in earnest, and have got not very far. We've largely "got away with SLD" because it tends to be a localized event.

So, regarding the comparisons:

IF we've lost a number of aircraft to a known but rare phenomenon (SLD) and havent managed to significantly mitigate the risk, what chance was there really of anyone being any more prepared for the VA issue of the form it took last month? And, realistically, what chance is there of being any more prepared a decade hence?

AND, suppose some unusual weather pattern happened to generate large areas of likely or possible SLD. Would that really leave authorities any choice but to close the airspace which represented a significant risk of SLD?

Oh, and before someone cites the existing icing regs: the environmental data they ultimately rest on is OLD and geographically concentrated, and may be unrepresentative of world-wide conditions today....

Sunfish

Your arguments are tiresome and not borne out by fact but only by your own imagination.

Your opinions have been registered, just like the rest of us. Hopefully you can't go on and on arguing to convince others by citing the same old "what ifs" that can not be backed by facts.

Regulations are codified, judgements are not.

His argument is the one followed by the authorities. He's right. Its not his imagination, its reality that VA shuts down airspace - he doesn't have to prove anything becuase he is simply explaining what is happening and will happen in future.

Refusing to accept the explanation of why its happening isn't an 'argument' or 'discussion', it simply a refusal to accept reality.

Peter We

The above is not Sunfishes arguement at all neither have I seen one posting which disputes what you say above.

The arguement has been about HOW MUCH airspace is closed and what level of ash is acceptable to fly in?

That ranges from ZERO which some argue for up to the maximum dense stuff which billows out of the volcano mouth which no one but a fool would enter.

My own position is that if I can see and eye ball pollution clouds or dense mist and avoid then it will not harm me. It may harm the bank balance long term in clear air with low ash levels but to date there is ZERO evidence to back that up!!!

So really the arguement has been over low density levels of ash.

We have also argued about computer and mathematical ash movement forecasts which have also been innacurate infact some may even argue Dangerous as they give FALSE confidence of where ash may or may not be.

Sunfish has argued the doomsday scenario of 100s of engines all requiring rebuilds at the same time. He has absolutely NO evidence to back that up.

Neither has anyone any evidence whatsover through history that low levels of ash are any threat to safety.

Until that evidence raises its head any restrictions other than NOT to fly in visible ash clouds or mist will just ruin our industry and jobs which I have a sneaking feeling that some here want (not directed at you) especially when those restrictions are not based on a demonstrable safety threat.


Pace

I don't agree with any of this.

This is supposed to be a discussion of an important issue in commercial aviation. It would help if people accurately evaluated the contributions of the discussants.

In my previous post http://www.pprune.org/rumours-news/4...ml#post5706296 I pointed out that for a risk evaluation, even a superficial one, four quantities were needed, which I labelled (a), the chance that current levels of ash posed no risk; (b) the damage which ensues if current levels pose no risk; (c) the chance that current levels of ash pose some risk; (d) the damage that thereby ensues. I pointed out that the risk is (a)x(b) + (c)x(d).

This is the way risk is assessed and has been for 299 years, and there is nothing anybody here can say that will change this.

Pace argues that (a) is 1 and (c) is 0. But he also agrees that, at some unknown level of concentration, (a) will no longer be (1) and (c) no longer 0.

Now, of course, the second term is not really a simple multiplication, but a sum: (c1)x(d1) + (c2)x(d2) +... + (cn)x(dn), where c1.....cn represent classes of concentration and d1,...,dn different levels of damage.

Sunfish's contribution to this assessment is to point out the various levels of damage that can ensue (the d's), and that many of those chances, the c's, are unknown, but that some of them can be estimated from history and science.

Mad(Flt)Scientist has pointed out inter alia that it is fruitless to expect those chances to be well-known in detail, by comparison with a case heshe considers broadly similar, that of SLD's.

I don't find any of this "tiresome". I find it essential to an appropriate risk assessment.

PBL

PBL

I do not question your arguement on risk! but if you read my previous posts you will see there are FAR greater demonstrated risks with a long history of fatal accidents which we do accept and think little of.

Ash todate has a couple of unfatal incidents in dense ash at night and no reported incidents in light ash in over 50 years and millions of flights.

The percieved threat and thats all it is does not warrant the restrictions and financial hits that light ash has caused.

If you want to avoid being killed in an aircraft then dont fly as there is always an element of risk.

Ash in low density is one of the tiniest risk situations and doesnt justify the reaction it has generated or the financial damage to the aviation industry it has created much of which has been media generated hype and scaremongering.

I can point you in many areas of aviation which do hold a far higher risk element and proven risk element if you want to improve safety but it aint ASH

Pace

This is true. Indeed, it is well accepted as a general phenomenon.

Before he was appointed to the U.S. Supreme Court, Justice Stephen Breyer wrote a book "Breaking the Vicious Circle" (Harvard U.P., 1993), based on his Oliver Wendell Holmes lectures at Harvard, in which he includes in Table 5 (pp 24-27) the risks and cost-effectiveness of U.S. federal legislation selected from Fiscal Year 1992. The cost per premature death averted ranges from $100,000 in 1990 dollars (widely regarded by many to be a bargain) to $5,700,000,000,000 (yes, you read that right). About half the measures lie over $8,000,000 per premature death averted, which is regarded by almost everybody who deals with these issues as very expensive.

Cass Sunnstein has a similar, but shorter table in Chapter 2 of his study "Risk and Reason" (Cambridge U.P., 2002), in which he says "it is well-known that there is a great deal of variability in national expenditures per life saved."

Both Sunstein and Breyer deal with the question of how to approach this and other phenomena.

So now we are agreed on this phenomenon, what is your argument to get from the phenomenon of variability of response to risk (on which we agree) to the conclusion that flight should not have been restricted (on which we don't agree)?

PBL

PBL

Your response deserves a carefully though out reply which I will enjoy giving but sadly I have to do what I talk about too much see you couple of days ;)

Pace

Iceland Issues Second Warning on Katla
 

Today, May 27th - Iceland Issues Second Warning on Katla, from:

2nd Iceland volcano issues ominous warning - Europe- msnbc.com -
A second, much larger volcano in Iceland is showing signs that it may be about to erupt, scientists have warned.

Since the start of the Eyjafjallajökull eruption, which caused cancellations of thousands of flights in Europe because of a giant ash cloud, there has been much speculation about neighboring Katla.

An initial research paper by the University College of London Institute for Risk and Disaster Reduction said: "Analysis of the seismic energy released around Katla over the last decade or so is interpreted as providing evidence of a rising ... intrusive magma body on the western flank of the volcano." "Earlier seismic energy release at Katla is associated with the inflation of the volcano, which indicates it is close to failure, although this does not appear to be linked to seismicity around Eyjafjallajökull," it added.

"We conclude that given the high frequency of Katla activity, an eruption in the short term is a strong possibility," the report said. "It is likely to be preceded by new earthquake activity. Presently there is no unusual seismicity under Katla."

Icelandic President Ólafur Grímsson has warned governments around Europe that a significant eruption at the volcano is close. "We [Iceland] have prepared ... it is high time for European governments and airline authorities all over Europe and the world to start planning for the eventual Katla eruption," he said.

The UCL scientists, engineers and statisticians also criticized the response to the earlier eruption."The impact of the eruption on regional airspace could have been predicted and better prepared for as the growing problem of aircraft-ash cloud encounters has been recognized for decades," the report added.

"Similarly, the potential for ash clouds, specifically from Icelandic volcanoes, to interfere with air traffic in UK, European and North Atlantic air-space was appreciated by the aviation industry well before the start of the Eyjafjallajökull eruption," it said.

"The response to the ash cloud’s arrival in UK and adjacent airspace was entirely reactive and therefore less effective than it should have been."