europe seems ok
have a look here to see where all the planes are currently flying - UK looks a bit bare
So the UK Met Office closed European civilian airspace on the basis of one computer model, which it didn't check against reality. We already knew that the great volcano shut-down was based on a model, but we didn't know how little atmospheric sampling was performed to test the simulation against the atmosphere. It turns out only …
I've never heard of Mexico City's airport closing because Popocatepetetete... Popocatapippel... "El Popo" was erupting. I remember driving to work one day and getting the garage attendent to clean my car. When I went to go home it looked worse than it had in the morning... and yet the planes were still flying.
The NOTAMS have said since Thursday that IFR flights are not being accepted by the London FIR. However, VFR flights have never been stopped in either the London or Scottish FIRs and may proceed at their own risk.
In other words in England and Wales planes that operate by looking out the window can fly but head-in-the-cockpit flying on instruments isn't permitted. Of course, this still won't get you to the parts of Europe where all aircraft are grounded. This has included Holland and Germany.
The height limitation comes because VFR rules don't apply above 19,500 ft - flight above that is all IFR.
Notice To Airmen - notification of hazards or temporary changes to the rules of the air, always with a validity period.
Instrument Flight Rules - flying on instruments under air traffic control
Flight Information Region - a block of airspace with a single control point
Visual Flight Rules - flying by looking out the window, not necessarily under air traffic control. This is how most GA aircraft, gliders and microlites operate
Yes, it's a model - short of populating the upper atmostphere with an array of sensors, that was always going to be the case.
Does it fall short of reality? Yes, it's a model.
Were "mistakes made" and will "lessons be learned"? Yes. It's a model.
Does it err heavily on the side of caution? Yes, because erring the other way involves probable loss of life (http://tinyurl.com/y4mmqqa)
I appreciate it may not be as accurate as everyone wants, but I'd be interested to know how accurate it needs to be before it's above criticism. Given the single event they've had to model from and the consequences if they get it wrong, this article sounds a little churlish to be honest.
Never let it be said the Reg let an atmospheric model pass without criticism.
I assume this is part of El Reg's attempt to discredit the Met Office and anyone else involved in climate change and, although the BBC are part of the conspiracy too, I thought this was interesting...
"A high-tech plane with sensors calibrated to find volcanic ash has landed after finding 'a lot of muck' in UK airspace.
Aeronautical engineer Dr Guy Gratton of Airborne Atmospheric Measurements, said he would advise against flying passenger jets in those conditions. "
The Met. publish a model that predicts ash movement which they provide to the civil aviation authorities, who then make a judgement on the information supplied against their standards. They freely admit they can't tell the particle distribution, and that the samples they could take proved accurate.
Airspace is big, and their resources small, would you rather a few airlines had financial difficulties, or a few airliners plunged into the Atlantic. I guess the airlines prefer the latter because they are insured.
Also we have become heavily dependent on one form of aviation transport model, one wonders how much BA wish they still had a fleet of Viscounts for short haul, they may be slower, and fly lower, but they wouldn't be grounded. And isn't their any reason why the airlines didn't jump up and say, give us the tools and we'll fly some sampling flights. i understand the Finns have two F14s that did and are now in need of a severe engine refurb.
Yet again we learn, don't put all your eggs in one basket.
I'm the one with peaceful, and above all quiet back garden where bird twitter is unbroken by aircraft. It's heaven.
We know you don't like the Met office, but to accuse them of shutting down airspace is poor reporting at best... It is NATS who control the airspace and control if it is open or not, they are merely acting upon predictions of where the ash will go and at what height based on models AND observations by the Met Office, NERC etc. alongside the recomendations of the aircraft manufacturers who are currently saying that no ash is acceptable for a jet engine to fly through.
Lets have a look at the Met Office's
range of products:-
24 Hour weather forecast - maybe 50% correct
5 day weather forecast - probably 20% correct
Seasonal weather forecast - at best 10% correct
50 year climate change forecast - 200% correct, so we are told.
Where do you think the ash prediction model fits in to that league table of mediocrity?
"And, guess what, you _can't_ see the ash - even if you fly through it."
The two prior issues with ash were at night, at the densities that cause problems you can very clearly see it during the day time (if the clouds are brown, you don't fly through them). For point of reference as to how trace amounts of ash have no real impact on operation take a look at Mt St Helens and the scope of its ash cloud during the 80's
The reason NATS have shut down IFR service is because the internationally agreed standard, one which they can override, is that there should be no detectable ash and was never intended to close a continent. It exists to allow for the rerouteing of flights around possible issues much as they do with storms and lots of other weather events. NATS took its advice from the MET as did everyone else.
Additionally the MET effectively did close EU airspace. The MET is the designated volcano centre for western Europe so all national bodies in this part of the world take the lead from them in terms of what is going on. When they finally revealed the source of the data rather than just an advisory most of the countries started opening up their airspace again because it is clearly a crock of shit.
Civilian planes don't have any radar. And actually planes can see the worst of it, and it is only the worst of it that causes problems. A number of airline test flights have flown around (but not through) the ash cloud to see whether they can detect the limits of it, and they can. The Finns (if I remember correctly) flew a couple of military jets through the middle of the cloud and got the engine problems that you would expect from coating your turbines and tail pipe with glass. It is easy to detect and easy to avoid, but the UK government (and a few European ones) have utterly over-reacted primarily to make it look like they are doing something before the election.
"Given the single event they've had to model from and the consequences if they get it wrong, this article sounds a little churlish to be honest."
Since I have pretensions to being a scientist, I'd say that "Given the consequences if they get it wrong, they should steer clear of models based on a single event and perform some bleedin' experiments.". But no. Faced with a continent-wide shutdown costing Lord knows what, clearly sending up a few balloons is an absurd idea.
Like anything else, the airlines do a cost - risk analysis and don't want to:
1) Do more maintenance than normal (overhaul after every trans-atlantic flight for next few days).
2) Violate any remaining warranty on all the engines of any planes servicing those flights.
3) Buy the extra fuel to circumvent the ash clouds, or extra fuel to compensate for any decreased efficiency from any "glazing".
The airline passenger insurance companies have already denied all claims for extra accomodations, meals, and other required expenses for spending extra time in a foreign country: Sorry - Act of God. SOL.
And they can take the moral high road claiming safety is top concern.
I wouldn't mind to take an aeroplane up and perform measurements and stuff, but something more like a glider than an airliner, and I'd stay over land. Why? Because without motors you can still land perfectly safely, though it's a bit of a pain with a boeing or an airbus (but it's been done). In fact all my flying experience is in gliders, without motors. So yeah, I'll come along, no sweat.
What is inexplicable to me is just how shortsighted the airline companies are being. If just one airliner has any problems whatsoever over the next few days, it *will* be attributed to ash by the gutter press. If that happens, the losses of revenue to date will be small compared to the resulting loss caused by people walking (or more accurately, running) away from flying in their thousands, and for the foreseeable future. There is no security theatre that can be put in place to deal with this situation, as happens when bombs or whatever can be implicated. The travelling public are being told to trust the airlines and the governments that it actually IS safe - and the evidence is not that strong one way or the other.
I'm very risk-tolerant when it comes to flying, but I'd be thinking hard before I got on a plane at the moment, because there isn't anything on which to base my risk assessment. The fact that the Minister for Transport went into a closed meeting with representatives of the airlines yesterday, and then came out saying "Oh, everything is really alright" just fills me with suspicion.
with computer models to do proper forecasting.
This doesn't really surprise me since the same thing is happening with weather forecasting and they keep screwing that up for the same reason, decreasing number of world wide weather stations and increasing reliance on computer models.
The end result is the same, completely bogus forecasting, a broken clock seems to get the time right more often...
Ok, so who's volunteering to fly over the Atlantic , safe in the knowledge that ash hasn't fallen on Biggin Hill yet ?
The MO need to predict _in_advance_. As the joke goes, prediction is hard, especially of the future. And its easy to criticize if its not your prediction that causes hundreds of deaths.
Yes, measuring the density of the ash is a good thing. That requires specialised aircraft (adapted radar, particle protection on the engines, etc.) of which there aren't many. Aircraft that have flown through the ash (the Finnish air force) demonstrate how much damage it does.
Sure, some aircraft have flown at safe levels. They took a guess, and flying with the predictions of the Met services (and no passengers) landed safely. But tens of thousands of flights take place over Europe every day. How confident are you that, with a poorly tested model (not many volcanoes around here, you see), you can predict paths for aircraft so that not one in 50,000 flights gets hit ?
Its easy to claim over-zealous when its not you who has to make the decision. Meanwhile, airlines that decided it wasn't economically worth investing in dust-proofing their planes are looking at someone to sue to recoup their losses, and pick on the Met Office.
... to issue a flight ban. If testing was ineffective, it could be because they're not called upon to regularly check density levels of volcanic ash rather than some percieved ineptitude. They probably are struggling, but I think I'd rather err on the side of caution than let people go whizzing off into the wide blue yonder, shortly before plummeting to earth Wile E Coyote style.
Considering the aircraft manufacturers are unwilling to certify their planes for flight through the ash clouds it isn't just the Met being cautious either.
Paris because she's still open to traffic.
So lets see Ash in the air can cripple civil aviation, and lose it zillions a day.
Add to that that the RAF can't fly as they all use fancy jet engines. So that the air space undefended then.
What is the response, one aircraft hastily fitted with sensors that flew 4 flights the first of which didn't even find the cloud as they were using Met office data as to where it would be.
Meanwhile the Met office dust off some software they developed in 1986 to track fallout.
Well I suppose we are lucky that the cloud of ash wasn't radioactive this time, otherwise the whole country would be shut by the Met office.
You don't like the anthropogenic climate change theory. You don't like institutions that appear to support it. You'll have a go at every opportunity, granted. But do yourself (and everyone else) a favour and PLEASE try to keep a bit of perspective; have a look at http://www.flightglobal.com/articles/2010/04/16/340727/pictures-finnish-f-18-engine-check-reveals-effects-of-volcanic.html . Now tell us all whether you'd be just fine with flying in a plane whose engines were in a similar state to those illustrated in that article. Didn't think so, because any other answer would indicate that you were stark slathering swivel-eyed windowlicking bugfuck nuts. The Met Office, with limited resources, issued advice that was extremely cautious, knowing that it would be used to determine whether flights carrying thousands of people might be put at risk. You know what? They still put a shitload more effort in and obtained more data than a publicity stunt with Willie Walsh did. NATS took their advice on board, and as noted above NATS took the decision, and quite rightly adopted a highly bcautious view also.
I am admittedly a sceptic of anthropogenic climate change - but, as the saying goes, I may be stoopid but I'm not THAT frickin' stoopid.
My little lady is supposed to be joining me to spend the rest of her life with me out here in the east this weekend - but I would rather wait a few more weeks than have her drop out of the sky chasing me halfway around the world
.... I think you are actually making the same point as the journalist - i.e. what was needed was evidence. No model will work without the figures to be plugged in to it. It seems to me that the Finnish Airforce were put into the position of fucking two engines because no-one else was producing data. This article clearly states that a few balloons and use of planes flying at lower altitudes might have produced some hard data. Now, maybe it is not just the Met Office that could/should have done that, but it certainly seems to me that the Met office has been derelict in its duty, and that the whole thing needs a damn good shake-up to clearly define what its role is, and how it is going to do it (and climate-change research is not part of its role).
The solution is quite simple - get the airlines, crew, cargo shippers and passengers to sign a mutual disclaimer that absolves each party from responsibility in the event of a crash resulting from flying through ash clouds. Aircrews get a bonus and anyone willing to fly themselves or their cargo do so entirely at their own risk. The only other danger is to residents in the path of the falling aircraft but chances are it will be over sea or lightly inhabited areas when flying at ash cloud heights. You pays your money and you takes your chances.
I know the Met Office is a favoured target of El Reg but a bit of background checking wouldn't go amiss. For example, ESA have also issued a model based incorporating satellite observations - http://www.esa.int/esaCP/SEMKDU9MT7G_index_0.html
And it was NATS that decided to shutdown UK airspace as they state, there is no threshold at which volcanic ash is acceptable for aircraft - (Too many sources to list, here's a google search instead) http://www.google.com/search?q=nats+threshold+volcanic+ash
I keep hearing talk - especially from the chaps at Nats that upon receiving news of the cloud they have implemented a "Contingency Plan".
What is their "Contingency Plan"? - It looks to me like the ability to say "Stop" when confronted with data, not generated by them, which is compared to a rule book issued by the European agency. Anybody could do that. They appear to have no executive authority, at all.
In my book, a "Contingency Plan" would include: Alerting Ferry companies to put on extra ship. Alerting coach and rail companies to put on extra vehicles and coaches. Contacting embassies abroad to implement previously agreed visa and travel waivers to ease the chaos abroad and alert UK "Border Agency" to expedite passage back into the country without petty -fogging beurocracy likely to try the patience of the most stalwart returning "rough sleeper" and family. A phone number to someone with real information instead of a time-serving jobs-worth would also not go amiss.
When this is all over there should be a complete clear-out of these hopeless Apparatchiks into some less demanding role.
"The Met Office is the north-west European Volcanic Ash Advisory Centre with responsibility for issuing the Volcanic Ash Advisories for volcanoes erupting in this area in line with internationally agreed standards and processes. This means the Met Office’s role is to support NATS, CAA and other aviation authorities decision-making."
Apparently the other main input into aviation authorities' decision-making is the rated tolerance of retail jet engines for volcanic ash in the atmosphere, which is, by them, zero. Fly through even a whiff of that stuff and you've lost your warranty. Well, "warranty" isn't quite the right concept, and it may be over-strict. But for an airline to fly a plane in conditions where the manufacturer's advice is "Don't fly the plane in these conditions" is, correctly, a dreadful liability.
Up to now, keeping aeroplanes well away from the effects of volcanoes evidently hasn't been very difficult.
I must say I was shocked though by one commentator's description of the failure scenario: "The engines stop working, the plane goes down and everyone dies." Surely that doesn't -always- happen?
The MET only has a remit by the ICAO to run the London VAAC and provide expected Ash distribution for the next 24hours. It is not responsible for sending monitoring gubbins into the sky.
The reporting to the CAA and NATS can then use other information as they see fit - test flights, balloon instrument monitoring etc.
... the question must be "WHY is it not in their remit?" If they are expected to provide infomation in the form of forecasts, then they need the data from which to make the forecasts - or am I living on a different planet (again)?? If they don't have the ability to collect the relevant data then they are worse than useless, because it is just guesswork with a machine that goes "beep"!
Worst case, all engines fail - oh, and you can't see where you're going, which MIGHT under the Top Gear over/understeer principle be considered a blessing... http://www.youtube.com/watch?v=EQWPumtDXk0
@trox: They don't do air traffic control, they provide advise to them. And their short/mid term weather forecasts are pretty accurate, most people claim they aren't based on TV broadcasts where rain cloud/sun is put on top of a 100sq mile area and automatically assume the forecast is crpa because it did/didn't rain over their house. Try one of their localised/bespoke forecasts if you want accuracy.
BTW, I don't work for the met office.
"Field testing from balloons ... would have filled the knowledge gap."
So, we need to cover an area of about 4,000 miles square at, say, 200 mile intervals or better, sampling every few thousand feet up at six-hourly intervals. Even if there were some means to perform remote assessment, so that it wasn't necessary to collect the samples after descent and examine them under a microscope or whatever, at least half of the 400 field stations would have to be sea-based.
Rather than the rant against the Met it might be nice to know a bit more about how LIDAR works and to have a few details of the software they and the other eight VAACs worldwide use to model pollution incidents and the sort of kit they run it on.
With their budget priority, the same as it was in 1986.*
* Please refer to in-depth analysis and inventory reports of that time. Filed on microfiche in 1991, and conveniently stored in the bottom drawer of a locked file cabinet in the disued lavatory in the basement of the Official Government Records Repository - the closed tube station under the Thames.
Thank you for your interest!
How many? 20? 30? 100?
Will you chip in for the optical particle counters required for each one too? And the ground crew (plus transport) to deploy, follow and retrieve each balloon? And the trained technicians to analyze the data within the 1-2 hour window in which the data will actually be useful?
And then will you pay for their upkeep and training during the 20-30 years in between the extreme incidents during which their immediate deployment will be useful?
... that is what our taxes should be paying for - readiness in the case of emergency. Nothing you have listed is useful only for this particular type of incident (pun not intended), and so should be part of the civil defence kit that should be maintained routinely. However, preparedness for eventualities is not "efficient", and so all civil defence stocks have been run down to nothing.
...it would be great to have the government provide more field work equipment for tracking this kind of event (though I think that we'd be better off having more aircraft, rather than more balloons). However the cost of providing this would be very high, and the equipment would not be as useful for other work if it was required to be readily deployable with 24 hours (our department conducts field experiments in Borneo, Chile, France, etc, as well as ship-based campaigns - none of which would be possible if the equipment and researchers were on call for UK work). If such a network was to be setup it would have to be funded in addition to current research work, it could not be funded by moving money from other projects.
Let's say the composition wasn't as bad as suspected, and only 0.5% of jet aircraft/helicopters would crash.
Is that still an acceptable amount? Compared to a few days cessation of business?
I'd rather not have jets landing on my house, thanks very much. Safety first, as they say.
Considering how vulnerable jet engines are to foreign objects, caution is the best option.
First off, I agree with everyone saying el reg is being too rough on the the Met here. Modelling is difficult business, and it's not their job to collect Europe-wide data. Expecting them to fly *planes* into the cloud is daft too given the potential problems. It's really not safe to be all "well, we're 50 miles outside the ash so it's fine" either, so it's not like the model being slightly off REALLY would have effected the airspace being closed.
Second off, @Mountford D "A question of risk". I doubt the airlines would go for it even if they were permitted and got people to pay A LOT to get the f' out of the airports. To be honest, the risk of a crash may not even be that high. But, they probably would be putting like 10 years worth of wear on those engines in a single flight. No airline would go for that! There's no air filter on a jet engine, it'd be like driving your car through a sandstorm, or down a gravel road behind another car, with no air filter. The car probably won't die mid-trip, but I doubt any of you would do it!
I'd agree with this post except the NOAA (and US Navy and Air Force) still fly real airplanes into real hurricanes to gather real info to validate the information provided by satellites, ground radars and models. I suspect these flights are not particularly "safe".
I also suspect the Met Office felt it was doing so well with the climate change model (no controversy there) the ash dispersion model was a "doddle".
Many thanks to nichomach for posting actual primary sources (the Finnish pictures etc).
Any gas turbine engine experts here? I'm not claiming to be one but I do know a few things. Here are a couple which just might be at least as relevant as Willie Walsh's opinions (and a few others round here too).
(1) Turbine tip clearance
To get best efficiency, modern gas turbine engines have tiny clearances between the (moving) end of the turbine blades and the (stationary) enclosure in which they rotate. Anyone know the kind of dimension we're talking about? I'm thinking it's of the same order of magnitude as the larger ash particles. So, what do readers think will happen to the blade ends and the enclosures, either immediately or later, when they've been rotating at (say) 10,000 rpm for a few hours in an enclosure containing something with similar effects to a sandblasting mixture? Hint: it won't be pleasant. Think about taking the lid off a modern hard drive, scattering a little talcum powder inside, and seeing if it still works reliably for long.
(2) Single crystal turbine blades
Modern gas turbine engines are miracles of engineering and science, with complex designs (including complex control systems) intended to cope with a variety of predicted conditions. Flying through the kind of volcanic ash which produces the effects shown on the Finnish photos is not one of those conditions. The turbine blades in many engines are manufactured from single crystals in order to allow them to resist the extremes of mechanical and thermal stress they routinely have to cope with. When they end up looking like the ones in the Finnish pictures, they are no longer single crystals and as such they are greatly weakened, and in due course will fail even under normal stress loads.
A Engineer (not a metallurgist, but solid state physics was my thing once upon a time)
No, they don't *always* fall out of the sky. There's the documented case in 1982 which the BBC wrote up. The 747 was at 36,000ft when all four engines died. By 12,000ft enough glass had cleared itself from the engines that they could restart - had the engines not restarted then, they would have had to ditch, bcos there was nowhere on land they could set down.
Don't know if that is or is not correct. Pretty suspect if it is. The physics, mathematical techniques and AFAIK the number of sensors have *all* improved.
Note 3 other facts.
Procedures *do* exist to handle the simultaneous shutdown of all engines.
Other parts of European airspace *have* re-opened, some of them undoubtedly flying through the UK sectors. If *nothing* happens on those flights the Met Office will look like it's crying wolf.
A number of long duration "weather reconnaissance" drones exist which could run sampling missions. These vehicles are usually propeller driven and while not very fast could sample most of the airspace fairly quickly. Being uncrewed if anything did happen they would be expendable.
A Engineer here again.
Some readers may be aware that aircraft use things called "Pitot tubes" to measure airspeed. Fwiw, airspeed is *not* the same speed as you'd get from asking a GPS how fast you're moving, because airspeed factors in the influence of the wind as well. This is an important difference if you want the aircraft to stay in the air.
In June 2009 Air France flight 447 crashed into the Atlantic killing all 228 people on board. It is suspected that simultaneous identical faults on two of three Pitot tubes, leading to misleading numbers being reported, caused the aircraft's control systems to "do the right thing" based on the information received, with disastrous results.
It is entirely plausible (indeed, predictable) that Pitot tubes will be adversely affected by atmospheric ash, either immediately or as time goes by.
There are probably other aircraft systems and sensors that can be affected by ash too. Engine and airspeed sensors just happen to be quite important to safety. BA and BAA revenue isn't really quite so safety critical.
The ash cloud from Eyjafjallajökull was quite mean and big few days ago. The eruption now is about four times bigger then last eruption in 2004 in Grímsfjalli.
Ash also makes a jet engine into a scrap engine in no time. Things will get better when Eyjafjallajökull has stopped erupted. But until then, hope for the best.
"Fwiw, airspeed is *not* the same speed as you'd get from asking a GPS how fast you're moving, because airspeed factors in the influence of the wind as well. This is an important difference if you want the aircraft to stay in the air."
Errr ... no ... the figure derived from GPS is the groundspeed and THAT factors in the wind. The airspeed is the speed of the aircraft through the air ... it matters not if the air is moving.
Just a bit of pedantry ...
Non-UK readers might miss the reference to "Mystic Meg", who does an astrology column for a British newspaper.
There is some concern that Eyjafjallajökull's big brother Katla might be next, and I've spotted at least one web page which blames global warming for this: apparently, the heavy glaciers on top of the Icelandic volcanoes squeeze the rock down, holding the lava in, at least for a few extra years between eruptions.
While Eyjafjallajökull being smaller than Pinatubo, which bought us only a decade's respite from global warming, doesn't affect that issue... Fox News apparently thinks that Katla might plunge us all into a new ice age. And here I thought it was ocean salinity turning off the Gulf Stream was how global warming was supposed to start an ice age.
A Engineer again again.
But this time you don't have to listen to me. Instead, listen to Professor Alan Turner of Sussex University, former head of a relevant Rolls Royce research organisation, someone who might just know something about the subject.
"Alan Turner is a Professor Emeritus in the School of Engineering and Design at the University of Sussex, UK, and Founding Director of the Rolls Royce Aero-Thermal Systems Research Centre. For over 25 years, his main activity was aero-thermal systems research on large turbofans (Trent) and military engines at Rolls Royce plc"
Large turbofans (such as Trent) are what power all modern long range civil aircraft.
Interviewed on BBC R5 Live, starting at about 2h 7m in.
Turner or Walsh. Take your pick.
Doesn't show up on aircraft's weather radar (or inded the met offices radar) and is not visible at low concentration levels, but those low levels are enough to cause serious problems.
Yes BA flight 9 survived the experience, but FFS having a go at the MET for using models to estimate where the ash (which doesn't show up on radar) will be is a bit childish really.
And for those who have said fly the planes lower, there are a host of problems, not even considering the extra fuel burn
But of course reasonable scientific explanations must be ignored because we must put profit before safety.
Really Andrew, you disappoint me with this somewhat childish swipe at the met office.
There is patently not a problem.
Yet people are queuing up to make 'authoritative' claims that there is. It's beginning to sound exactly like Global Warming....
What is it about various sections of humanity that makes them want to pretend the end of the world is coming? And why do the press keep reporting this? ?????
Side note. Single crystal turbine blades are *very* expensive and AFAIK remain confined to military gas turbines. Unlike Silicon they are not grown from a seed crystal. Gas turbine blade clearance is on the order of a 4-8 mils (c100-200 micrometres, which is tight but I think the ash is *smaller* than this)
Dr Turner makes a more general point. All modern aircraft turbine blades are *cooled*. They use "300micrometre holes in about 6 rows" The sand melts and blocks the holes. This mechanism is what allows blades to operate at (IIRC) 80-90% of their melting point. Disrupting this airflow is therefor a Very Bad Thing.
Dr Turner criticized airline test flights as failing to test for loss of power after landing and borescoping the engine for damage. Damage would also show up as worse fuel consumption which should be apparent given the high resoltuion of engine management data recording. Given the revenue losses they are having airlines ideas of "Acceptable risk" might well be a lot different to what the general public's is.
Dr Turner makes a lot of sense but I think he may underestimate the ability of an engine to recover if shut down at altitude and allowed to glide to lower (12000 ft) levels to crack the glass off. He did point out that airlines in the Middle East do fly into dust storms at 30 000 ft so in this area its effects on engine life are quantifiable. At the end of the day an airline has to be in business to be worrying the overhaul costs on its engines. For some not flying *now* might be the last straw.
http://www.rolls-royce.com/civil/products/largeaircraft/trent_500/ - don't know if this was the first, so there may be earlier.
It's not specifically the single crystal stuff that matters, it's just that these things are designed to work safely and efficiently in specific circumstances which are well explored, and for efficiency reasons they work far closer to the margins of safety than folk outside the industry may appreciate. Move outside the standard operating envelope for any length of time, and you are entering unexplored (but not unpredictable) territory. Here be dragons.
I stand corrected.
I commented that blade cooling lets turbine blades operate *astonishingly* close to their melting points. Knocking that system out puts the engines under a *lot* of additional stress.
I guess the biggest database on this subject are aircraft flying through sandstorms in the Middle East.
In electronics it is sometimes called the "Safe Operating Area."
Here are some words from Rolls Royce on the subject of single crystal turbine blades. These particular words are from Sir John Rose, Rolls Royce plc Chief Executive, in a 2009 speech to the Royal Society of Arts on "creating a high value economy". Not totally definitive, and doesn't illustrate the history of single crystal going back several years, but will it do for now? It's the best I could quickly find.
Let me illustrate the point by taking just one small component. This is a ‘single crystal turbine blade’.
• It’s one of 66 in a Trent 1000 engine.
• It is grown in a vacuum furnace from a single crystal of a proprietary Rolls-Royce alloy.
• It operates in the high-pressure turbine, where gas temperatures are up to 1,600 degrees centigrade – that’s around 200 degrees centigrade higher than the melting point of the alloy from which it is made.
• It delivers the same horse power as a Formula One racing car.
• Because of the extraordinary precision required to ensure maximum efficiency and safety, the blade’s dimensions cannot be ‘out’ by more than 10 microns – that’s 10 times less than the width of a human hair.
• Yet, for all its complexity, it travels seven million miles between major services.
• A component of this complexity demands the close involvement of an enormous number of parties outside Rolls-Royce: in this case 37 universities and research centres around the world, 35 large companies and 34 small or medium sized companies.
• Unsurprisingly, it is not cheap. In fact, this small component costs around $10,000, the equivalent of over $1,000 an ounce.
Rose goes on to mention the Electronic Engine Control (aka FADEC), whose programming allows the engine to operate close to the limits of **normal operating parameters**. What he does't say is that ash ingestion is not within those "normal operating parameters" and the EEC's programming almost certainly is not intended to cater for those circumstances.
The traditionally engineered safety margins which might have been expected in the days of analogue controls have been sacrificed in recent years and in many industries in the interests of better economy. Consequently there is now less "wiggle room" for safety when exceptional circumstances do occasionally arise.
Full text (worth a look) at http://www.thersa.org/__data/assets/pdf_file/0007/249154/Rose-RSA-speech-10-November-2009.pdf
The single crystal turbine blades are operating in gases whose temperature is above the blade's melting point, hence the critical importance of the cooling vents mentioned above by various folk.
Don't take my word for it, read the words of John Rose, CEO of Rolls Royce plc, addressing the Royal Society of Arts on "creating a high value economy" (it's worth a read anyway).
For the "single crystal blade" stuff start at page 4 of
"In electronics it is sometimes called the "Safe Operating Area."
Indeed. And if you look at a chip datasheet, it will typically say that permanent damage may result from operation outside the safe operating area. It won't say "if you go 0.1v outside the safe Vcc for 5 minutes you'll probably be OK". But that's what the airlines want the engine companies to say, except in this case the airlines won't actually be able to say how far outside the "safe operating area" (in this case, no ash) their aircraft have been or will be going.
Apologies for the duplication of the single crystal stuff. One of them got lost in the post, so I tryped it again (but shorter) and then it re-appeared. IP packets have this problem too, sometimes.
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