Ash clouds threaten air traffic

[spamcanppl]

hopefully this one won't be deleted by the mods.

I have just read that the RAF might have a related prob with their "Sentry" a/c operating out of Waddington, three engines on one a/c. Anyone know any more about this

[mary meagher]

Overreaction? don't think so.

Flying through volcanic ash is not a good idea. Depending of course on the concentration!

European aviation is regulated by an amalgamation of polyglot officials, penetrated, tested and stretched by national and private enterprises of widely differing standards. Under the circumstances, the regulators have done a reasonable job under pressure from despairing airlines yearning to leap into the air once more!

As quoted in the Wall Street Journal, Ken Williams, fleet captain of Alaska Airlines, says that they treat ash clouds with the greatest respect. When Captain Williams receives an alert, aircraft of various types, without passengers, are flown to measure winds and temperatures, providing additional data to be able to map and avoid ash clouds. Alaska pilots are given plenty of simulator practice in dealing with ash.

The Alaska Volcano Observatory and the United States Geological Survey make it their business to observe, classify and notify Volcano ash hazards to aviation. Says the USGS, "Volcanic activity threatens safe air travel when finely pulverized glassy abrasive volcanic materiel is explosively erupted into the atmosphere and dispersed ... in flight paths. ... Ash can cause jet engines to fail in flight..."

Iceland, as a nation upstream from Europe, frequently suffers from volcanic activity. Now that winds have shifted, its their turn to shut down the airports. Clearly, Europe as a whole will need to sponsor the equivalent of the Alaska Volcano Observatory and the United States Geological Survey as a matter of urgency. Sending test beds full of pax on ETOPs anywhere near ash clouds is not the ideal soluntion.

[Pace]

As for the visible versus invisible ash question - see ZQA'a link.

CaptainPaddy.

I did listen to it and the incident report was very interesting. visible versus invisible? Listen to the report again and you will note that his flight and encounter was at NIGHT!
Alaskan airlines limited their flights to daytime only which I would also support.
At night they would not know what they were flying through.
I also noted his referal to NO indications whatsover not even smells which if true would be very worrying.
I would also note that while possible that the damage they discovered from this accidental encounter was from the ash, there is nothing that proves it from his report.
What I would like to ask you is how would you have treated this possibly ongoing problem without causing major damage to an already strangled industry?

all the best

Pace

[fireflybob]

Posted by The B Word on the Military forum:-

Typhoon's Eurojet EJ200 has a 0.4:1 bypass ratio

Boeing 737's CFM-56 has a 5:1 to 6:1 bypass ratio (depending on the variant)

Tristar/B747's RB-211 has a 4:1 to 5:1 bypass ratio (depending on the variant)

Both can be damaged by contimination (such as sand, ice and ASH!), but the low-bypass-ratio EJ200 is far more likely to suffer damage over the high-bypass-ratio RB211 or CFM-56.

The F404s fitted to the F-18C/Ds of the Finnish Air Force (that were also damaged recently) has an even lower bypass-ratio of 0.34:1

[OpenCirrus619]

Iceland volcano - RAF suspends Typhoon flight training ash engine

Some comments about commercial traffic as well.

Worth knowing what people are reading.

OC619

[ATCast]

EUROCONTROL just announced that they started a "Volcanic Ash Safety Data Collection Function" in an effort to ensure greater coherence, at a European level, of volcanic ash related flight safety risk assessment and management.

See the link on Skybrary

Fly safe,

ATCast

[CargoOne]

Fresh Safety Information Bulletin from EASA
EASA Airworthiness Directives Publishing Tool

[BOAC]

The forecast for KEF is 110 g27 - should be interesting!

[peter we]

NATS are an ANSP (the only privately owned ANSP in Europe) and operate on a licence issued by HMG (well CAA). The government are signed up to the ICAO guidance previously refered to in this thread which states ANY ash, no fly. NATS complied with the conditions of the licence and closed the airspace it operates (on behalf of HMG), as did most of the North European ANSPs. The ball was then in governments courts to change the guidance in consultation with various other bodies. This it eventually did once they'd gathered more facts/data and it was then up to HMG to announce the changes.
Cynics amongst us may say that HMG hid behind NATS skirts so as to make it appear that NATS were the baddies of the piece and HMG rode the white charger to 'save' the airline industry. In reality everyone did exactly what they were supposed to do.

The airlines were the only ones who could provide the data to set the limits on ash levels. Until a week ago they were unwilling to do so and unwilling to set a 'safe' limit, probably becuase 'safe' is a relative thing.

When its comes to things like this its the CEO's responsibility to ensure that a business keeps function and pro-actively prevent a business disaster happening. It seems they collectively decided to avoid the issue.

[peter we]

I will be happy to stand corrected if it is so proven. Can you direct me to the source of your proof? I would like to check it out.

And how are you going to do that? get a time machines and go back take a Lidar measurement around the whole of Europe on hour by hour basis?

[WojtekSz]

Pace:

Quote:
Scientists have no standard for what concentration of ash is safe and what is a danger to aircraft, but ash cloud does scatter enough with time and distance to not threaten jets. Fallout from Mount St. Helens actually circled the globe three times before fully dispersing, but flights were grounded only within a couple hundred miles of the source.
...
Alaska airlines have been dealing with this and flying for years. They have built up their own operating procedures.
...
I am not an engineer or scientist but would have thought specialised engine testing, ground based in a wind tunnel where engines could be run for hours in various concentrations of ash would give a better answer?

i believe the answer was already given earlier down this thread: the tests you are mentioning, even if being a good idea, can not be done due to simple fact that it would be technically and scientifically difficult to decide on what type of ash to use for tests: harder or softer, more silica or less, with sulphus gases or without, etc.etc.
The amount of known ash types is so wide that it would be commercially not possible to select appropriate representatives for testing. And it would be difficult to extrapolate the results to different ash types without extensive test.
And hence the zero allowable ash concentarion directive - simple and effective.

Looking from the Alaska experience - they are simple avoiding any ash! OK Europe is smaller so we may have to invent a more creative way - but it may come at a cost. Hopefully just the cost of earlier engine replacement and not a a cost of passenger/crew lives.

[daikilo]

EASA?

Try this:
EASA Airworthiness Directives Publishing Tool

and if this isn't a wake-up call to you all, then I'll stay on the ground.

[HarryMann]

Have ash/particulate sample screens been suggested as a fit on every aircraft.. Surely weekly checks on such a device, visually at first, presuming several different particle size compartments, would allow a quick estimate of potential engine life reduction and SFC increase to be made, fed back to to engineering depts..
Surely such a device would be fairly simple to design, if not already in airborne service in some applications

PS. Excuse and forgive if this has been discussed, it is rare I post without reading the whole thread, but after 50 pages had ot come across such a suggetsion, so have to beg out... and jump forward quickly!

[brooksjg]

Yes - this has already been discussed.
No need for extra 'screens'.
Any one of several filters on turbine bleeds would do nicely.
See my previous posts here and especially over on the Engineers forum 'Ground Procedures for Ash'.

....but NOTHING will happen unless pressure is applied, decisions made, money spent and systems and procedures put in place! That's the danger of discussions such as this. Lots of suggestions but they eventually just slide beneath the waves unless someone, somewhere actually DOES something. (By the way, I have also made contact at CAA...we'll see...)

[Clandestino]

Those still believing that VA contamination is just theoretical construct could find the following link useful: Met Office - Icelandic volcano - observations. Near the bottom of the page you can see where and when the test airplanes flew and what they found.

DLR's Falcon made second test flight yesterday, pollution has significantly dropped but there are still doubts whether the area is completely safe. For the time being, report is available in German only.

MetAir has been flying its Dimona over Switzerland, I can't find link to their test results, though.

[Early Right]

Has anyone considdered difference of flying into areas where dust concentrations from land erosion, desert dust etc. (silt, sand and other non organic particles)blown up by wind and thermals vs. flying in areas where possible volcanic ash is present.
Dust by definition is 0.1-60 micron, desert dust and volcanic ash particles being blown over long distances are about the same size. Keep in mind that desert dust is eroded volcanic material by origin, look the same under the microscope and share many other properties. I do not reacall the whole airspace in Europe being closed for buisness when the muck from Sahara or elswhere blows in, as happens occasionally each year.
As for the ash from Iceland, it might have been localized over small portions of Europe in consentrations considdered unsafe for turbine powered aircraft, but for most of the European airspace particle concentration was by far less than seen during dust storms blowing in from Africa.

Enough said, as has been mentioned in this thread before, to eliminate all risk from aviation all aircraft should remain grounded and global transport should turn to alternative means.

[captainpaddy]

Sorry guys, my long winded post from last night has disappeared so I'll try to keep this one brief.

Pace and mm_flyer (I think that's your user name - your post seems to have been mislaid too) you are both correct about the nightime thing, which I missed. So perhaps the ash would have been visible during daylight but how easily discernable it would have been from cloud reamins open to question. Nonetheless, the fact remains that no other signs of an ash encounter were present. My company keeps harping on about how an actual ash encounter will show signs of abrasion on windshields, leading edges and nav light lenses, but this case proves that to not be the case. Lack of these symptoms does not mean no engine damage has occured.

Pace I can't understand how you can question the validity everything in an attempt to justify what has happened? The post strip down examination of the DC8 engiens showed ash deposits in the cooling passages. It was ash - no question. And why would you feel that the report of no other indications of an ash encounter might not be true? The report says that's what happened - why would this not be the case? I see more and more people and professionals qualifying everything to allow the possibility of things not being as they seem. Why is it so hard to see how that same logic could be applied to the new regulations?

Clandestinos link is very worrying. Test flights are finding ash out there in sufficient levels to pose the threat of damage. Why are the authorities giving the opposite impression?

I do not accept that there would be no airlines left if the regualtions were not changed. This was never going to last that long - although of course it may recur. Some may have run into trouble but most would have survived. Lets be very clear about this: This was an unprecedented occurence where high level winds were sustaining significant ash levels over most of Europe. Volcanoes have been around the whole time jet engines have been strapped to aircraft. When was the last time an ash cloud closed airspace over most of an entire continent? Just once - this last week. Yet we treat it as though the ash was with us for good. That is just not the case.

I have a major problem with amending regulations which are designed to prevent the possibility of serious damage or danger from a highly infrequent risk in order to appease business. Since when was the primary objective of safety legislation to ensure the viability of each and every company out there?

fireflybob, you bypass ratio infromation is interesting but misses the point. What you say is valid, but only for engines of the same size or thrust rating. A massive high bypass engine needs much more air than a small low bypass one. Also, it can be argued that if ash concentrations were high enough to cause damage to an engine, small or large, then the risk exists for every other engine too. It is the concentration that matters at the end of the day. I see no difference in the operation of military jets compared to civilian ones except for the possibility of different operating temperatures. Even then though, civilian engines are plenty hot enough to cause ash particles to melt.

[captainpaddy]

Early Right, what you say has been mentioned a number of times iin different places. (Not sure if it on this thread though).

In fact, it is not correct to say that desert dust is from the same origin as volcanic ash. They are created through completely different processes and have very different qualities. Firstly, dust is generally rounded and smooth and also significanlty larger. This means much less or possibly no erosion and abrasion on surfaces. Also, it is generally accepted that the melting point of dust is much higher than temperatures typically found inside a jet engine, so the threat of melting and deposits forming on turbine sections does not exists.

Volcanic ash is quite unique in that sense. A comparison with dust storms or similar events is not accurate.

[lomapaseo]

Once again, the smaller the particle (dust vs sand) the hotter it gets as it passes through the combustor.

The larger the particle (sand and young eruption volcanic stones that haven't fallen to the ground yet) the more likely it is to be centrifuged out the fan duct.

Volcanic ash particles often are made up of stuff that melts at temperatures lower than most earth surface dust-sand storms.

It's a statistical thing and you manage your way around it finding air clean enough to fly in.

[Rollingthunder]

Don't mess with Mum Nature or junk yard dogs.