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Ash clouds threaten air traffic

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Ash clouds threaten air traffic

Old 20th Apr 2010, 14:31
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Bruce Wayne asked
Was it? is that why the UK airspace is closed because they have found ash contaminant in the atmosphere?

Is it that simple ?

The aircraft that have been operating VFR don't seem to have encountered it to a level that has been detrimental to flight.

If the UK airspace has been closed due to contaminants, at what concentration are those levels and where and at what levels ?

Please, do tell.. the UK avaition industry would appreciate you imparting that knowledge, perhaps NATS too.
The first 12 minutes or so of Bang Goes The Theory are about the impact of the volcano of flights. There's a bit on the plane they kitted out to do the measurements, and a comment about how the levels in the cloud are really quite high.
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Old 20th Apr 2010, 14:32
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Yeah thats all well and good, until they have a engine our or a de-pressurisation then have to decend into the ash concentration !!!


and over what level of concentration would it be problem ? you can give it in ppm or gm/3 i dont mind...

so an engine out automatically means an aircraft cant maintain altitude?

better get on and revise those ETOPS regs !!

and an emergency descent isnt going to be a push the nose over and descend at flight thrust.. VmoMmo will be behind you.

yes in an explosive decompression (which are rare events) the objective is to get to a lower altitude, but you cant do that if you are over mountains.. the ground tends to get in the way.

also, we are not talking about prolonged flight over ash concentration of whatever level, and if an explosive deco happens at altitude you dont have long to get on supplimental O2 before its game over anyway.

if on a twin jet you loose both engines going over an ash concentration it's all rather moot as you are in a very expensive and heavy glider anyway.
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Old 20th Apr 2010, 14:33
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How do you know that, Airclues? The Finnish F18s and (Belgian?) F16s were flying in similarly clear conditions when their engines were damaged. This is the problem - it's not just flying through visible ash that can wreck the engines, and we don't know what the safe limit of contamination is and we have no way to monitor the actual contamination levels - we're blind on both counts.

As I and others have repeated, the damage is cumulative. I don't expect to see any engine failures today, but I am concerned that multiple failures may occur in the coming days or weeks.

People are being blinded by machismo and economics.
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Old 20th Apr 2010, 14:35
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Definition of ash cloud please

My two cents, which map is correct?, the CFMU issued at 1200UTC or the Met Office Sig Wx chart issued via Jeppesen at 1230UTC showing two completely different ash cloud concentrations.
At what concentration is ash in the atmosphere an ash cloud?
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Old 20th Apr 2010, 14:37
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Met Office

Just a point of fact that NATs are basing their decisions on information provided to them by the Met Office.

Have we all forgotten that this was the organisation that forecast a "barbecue summer" for 2009 and that the winter of 2009/2010 would be one of the "warmest on record"!

Wasn't there a recent forum stating "The Met Office - not fit for purpose", perhaps somebody from Nats should be questioning their relationship with the Met Office.

Jon
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Old 20th Apr 2010, 14:38
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Manofman, the reason your point is off kilter is that if an aircraft has a decompression or loses an engine, it will be making a landing at the nearest suitable airport anyway. The rate of accumulation of engine deposits is unlikely to further affect that flight, and the aircraft will be undergoing repair for the failed system so boroscoping the engines won't be much of a hardship. Normal ops planned in a significantly contaminated environment are different because they will have vastly greater exposure and the aircraft will be expected to continue in service.
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Old 20th Apr 2010, 14:42
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Not sure if this has been posted already (too many posts to go through) but i felt it was relevant.

BBC News - Test shows how volcanic ash impacts a jet engine <--- video, 3mins 8secs.

feel free to discredit it and/or ridicule me.

best regards from a klm passenger stranded in lima who is trying to get to the uk before work on friday)
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Old 20th Apr 2010, 14:43
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Volcanic Ash Contingency Plan

The document referred to in posts #1908 and #1914 infers that everyone has done, and continue to do , exactly that stated in the Plan. Rather comforting. I wish I had read it before reading some of the rubbish posted here.
Somewhat ironic that ICAO have used KATLA as an example in their Notams and Sigmets though.....................................................: eek:
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Old 20th Apr 2010, 14:49
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NATS latest statement / BA inbounds

Statement on Icelandic volcanic eruption: Tuesday April 20, 1500

The situation regarding the volcanic eruption in Iceland remains dynamic and the latest information from the Met Office shows that the situation will continue to be variable.
Based on the latest Met Office information, part of Scottish and Northern Irish airspace including Aberdeen, Inverness and Edinburgh airports will continue to be available from 1900 today to 0100 tomorrow, Wednesday 21 April, and also south to Newcastle Airport. Glasgow and Teesside airports will additionally become available in this time period. Restrictions will remain in place over the rest of UK airspace below 20,000ft.
Flights above the ash cloud are now permitted in the UK; between 1900 today and 0100 tomorrow, this will enable aircraft movements above 20,000ft in UK airspace.
We will continue to monitor Met Office information and the situation is likely to change during the course of the day. We will make a further statement at approximately 2100 today.
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 working closely with Government, airports and airlines, and airframe and aero engine manufacturers to get a better understanding of the effects of the ash cloud and to seek solutions. ENDS.

Therefore, as it would seem from this statement that GLA, EDI & NCL are all to remain open why should the current 22 BA inbounds have to divert as far south as Spain this evening as was posted earlier? Surely they will be spread across these 3 airports.
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Old 20th Apr 2010, 14:51
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As far as the Finnish F-18 Hornet engines are concerned, no actual damage has been proven yet - only particle concentrations spotted. The engine(s) have been dismantled and sent to Patria Aerospace who are examining them at the moment. Results can not be expected until a couple of days later. Finnish Air Force press release in English here:

Puolustusvoimat - Frsvarsmakten - The Finnish Defence Forces

Notice the careful wordings: "may cause" significant damage, etc.
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Old 20th Apr 2010, 14:52
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Riding Air, I think you'll find the Met Office forecasts are verified by what has been physically observed across the whole of Europe. Take your crosshairs off the Met Office, and find someone else to blame.

I think you'll also find its not the Met Office telling planes not to fly, its NATS / CAA, and they're basing their advice on ICAO guidance, and guidance from aircraft and engine manufacturers.

and I think you'll find the "Not Fit for Purpose" thread actually turned out to be fairly pro-Met Office (once the misinformation / scepticism was taken care of)

There is an AWFUL lot of rubbish / misinformation flying around in the press and on here, from supposidly educated parties. You'd think they had their own agenda or something, and were looking for a scapegoat...
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Old 20th Apr 2010, 14:58
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Just to defend the Met Office a little bit

"The output from the Met Office volcanic ash dispersion model has been compared with our neighbouring VAACs in Canada and France since the beginning of this incident and the results are consistent."

and

"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"

Maybe these standards and practises should change in the future, but that is how they are now.


"It is for the aviation industry and regulator to set thresholds for safe ash ingestion. Currently, world-wide advice from ICAO is based on engine and airframe manufacturers stating a zero tolerance to ash ingestion. This means that aircraft should not be exposed to any volcanic ash."

Nobody blames the ICAO so far. Looking at their website, they in fact seem quite pleased that everyone is following their guidelines.


On a separate note, I think the Eurocontrol area is different because the EU leaned on them to introduce a third "safer" zone. Not saying this is the wrong thing to do, but it is the reason I believe why their interpretation of the data look different.
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Old 20th Apr 2010, 15:11
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Ash Plumes and Long term engine damage

If one more person mentions long term engine damage i will track you down and bludgeon you with my wireless mouse..

its like talking about long term damage to shoe leather or the tread on your car tyres.

blades are replaced when they meet the time and cyc limits defined as an LLP (Life Limited Part) they are also inspected at intervals as well as trend monitoring, if there is any question as to the longevity they are replaced prior to LLP limits, Also with AD's and SB's they are often overhauled or replaced if they don't meet limits prior to intervals anyway.


As for flight into an ash plume, that will also warrant a bludgeon with a mouse, the plume is what is vented from this volcano.. 500 or a 1,000 miles away we're talking airborne contaminants.
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Old 20th Apr 2010, 15:13
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Regardless of the rights and wrongs of the airspace restrictions, I remain very puzzled by the legal process which appears to be operating in the UK and, for that matter, Europe.

NATS is a privately-owned ATM service provider. It is regulated by the CAA to ensure that it operates safely, in accordance with UK legislation etc etc.

NATS is not itself a regulator, and has no powers or indeed expertise to regulate. We can all laugh at a pig-ignorant Harriet Harman announcing that NATS is the UK's civil aviation safety regulator, but the fact is they are not and we should all be getting quite concerned about who is calling the shots.

Not least because when the aircraft start flying, closely followed by the lawsuits for unnecessary total closures when a more thoughtful response might have saved everone a lot of trouble and money, the lawyers will need a target.

Who will it be? The CAA is taking no apparent role in all this, so they can only be accused of standing well away from any decision making. Nothing new there.

The Met Office? Well, no, they are only advising on where the cloud is, not the engineering safety of aircraft operations in it.

Gordon Brown? Nice idea, but he'll plead that it was NATS/CAA/EASA/Eurocontrol/The Conservatives/etc etc etc, "I was only taking the expert's advice."

So who is actually preventing aircraft from flying? We know how it's being done, in controlled airspace, and that NATS are doing that. But is the decision to do it taken solely by NATS on its own authority, with or without consultation with others? If so they are on very shaky ground indeed.

I sense some very lucrative lawsuits looming although not by me, regrettably. But who is responsible, the final decision-maker, the person whose desk says "the buck stops here", who gets sued?
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Old 20th Apr 2010, 15:22
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If one more person mentions long term engine damage i will track you down and bludgeon you with my wireless mouse..

its like talking about long term damage to shoe leather or the tread on your car tyres.

blades are replaced when they meet the time and cyc limits defined as an LLP (Life Limited Part) they are also inspected at intervals as well as trend monitoring, if there is any question as to the longevity they are replaced prior to LLP limits, Also with AD's and SB's they are often overhauled or replaced if they don't meet limits prior to intervals anyway.


As for flight into an ash plume, that will also warrant a bludgeon with a mouse, the plume is what is vented from this volcano.. 500 or a 1,000 miles away we're talking airborne contaminants.
But wouldnt flying through this ash etc cause engine damage and reduce those cycles? and also increase the frequancy of inspections? I'm only asking out of interest before you kill me to death!
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Old 20th Apr 2010, 15:25
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VAAC=Volcano Ash Advisory Centres (please note the plural), there are nine of these centres around the world. See URL:
http://www.metoffice.gov.uk/aviation/vaac/

London VAAC is the smallest of all, only looking after the British Isles and Iceland and is part of the Met Office. Toulouse VAAC looks to be the largest, covering all of continental Europe, Russia, Africa and east to India and most of China.

Assuming they are all coordinated, particularly Toulouse and London VAACs, do they all have the same standards and predict concentration danger levels of VA to aircraft in the same way? From previous posts it would appear that Washington and possibly Montreal VAAC have different standards for measureing the concentration levels of VA and where these relate to be dangerous to aircraft.

According to a press article today (El Pais, Madrid, page 5) VAAC London pass data on the VA concentrations to Eurocontrol and base their predictions on a mathematical formula. Eurocontrol in turn submit the data to the 27 individual State Aviation Authorities, who take individual decisions concerning their own air spaces. The mathematical formula for preparing the data for the predictions is theoretical and has never been tested in real live experiments.........

In the meantime the authorities are thankful to the commercial airlines that have flown aircraft through the VA clouds for their input, as this will help them to determine whether their theoretical mathematical formula could be improved to provide more acurate prediction data....

With the cost of government, local, national and European to the tax payer, Europeans would expect that both VAAC in London and Toulouse would have been provided with sufficient funds to be able to conduct scientifically proved methods to predict the VA clouds and concentrations that would be dangerous to aircraft. The fact that the predictions are based on merely tentative theoretical mathematical formulas is a shameful situation and more so, as it could spell the ruin of many companies, airlines and many many others...

And NOW is the moment to conduct such experiments to find a scientifically based method for predicting the danger levels of concentration of VA cloud to aircraft.

Not in the budget.....never mind, let the politicians in all European countries pay for it, since it's their fault it wasn't done before....
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Old 20th Apr 2010, 15:27
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The CEO of Citi-jet released a press statement saying he believes British Airways took "undue risks in conducting test flights " , he also claims to have knowledge that "the aircraft involved in those tests were damaged" . He goes on to say that it appears safety authorities are being pressured by commercial interests. Source : RTE Ireland news at one.
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Old 20th Apr 2010, 15:27
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If one more person mentions long term engine damage i will track you down and bludgeon you with my wireless mouse..

its like talking about long term damage to shoe leather or the tread on your car tyres.

blades are replaced when they meet the time and cyc limits defined as an LLP (Life Limited Part) they are also inspected at intervals as well as trend monitoring, if there is any question as to the longevity they are replaced prior to LLP limits, Also with AD's and SB's they are often overhauled or replaced if they don't meet limits prior to intervals anyway.
No, it's not like that at all. Just like with shoes, you expect engines to wear out from normal use, but no-one knows how accelerated any wear may be, if there is any increase at all, with varying levels of ash contamination. To use your analogy, it's like expecting a normal pair of shoes to stand up to walking across a rough lava field - they just won't last as long, but you can't predict how quickly they'll wear out.

What is certain is that the ash will build deposits that do more than just cause wear - they will cause hot spots and thermal stresses or melting of components as well as affect the internal thermodynamics of the engines. How rapidly these deposits form is unknown. What level of deposit is safe is unknown. How big these deposits can grow before detaching is unknown. the level of damage caused by deposits breaking off is unknown... Therein lies the problem; there are too many unknowns to determine if flying through this amount of predicted contamination is safe.
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Old 20th Apr 2010, 15:29
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I thought this might be interesting. The previously grounded BAe146-301 from FAAM is currently airborne over Scotland at FL260. Let's hope it provides more answers.

http://www.faam.ac.uk/index.php/position
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Old 20th Apr 2010, 15:35
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At what concentration is ash in the atmosphere an ash cloud?
Someone posted that it was measured at over 2000ppm. The NASA aircraft that was damaged, flew through 600ppm I believe.

Correct me if I'm wrong, but if a an engine is producing 10,000lb of thrust, it would be consuming 0.01lb of dust per second ppm. Or 36lb per hour (16.36Kg).

600ppm would mean 9816kg per hour passing - and melting - through the engine.
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