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Ash clouds threaten air traffic

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Ash clouds threaten air traffic

Old 18th Apr 2010, 09:16
  #901 (permalink)  
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Sand v Volcanic particles

Sand is abrasive with a melting point above the temperatures found in a gas turbine engine.

Volcanic particles are abrasive and melt at temperatures lower than in a gas turbine engine.

Sand passes through - the other stuff melts and re-solidifies inside the engine.

Whilst is is undesirable to fly through either of these conditions, it would appear that sand is the least damaging - to engines at least.


The particles in the photo in #889 are what I reported seeing on my otherwise clean windscreen last evening.

Last edited by TRC; 18th Apr 2010 at 09:19. Reason: Added p.s.
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Old 18th Apr 2010, 09:18
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Remember: There is a search tool on this site...

A reminder to those who haven't read all the entries in this thread, there is a search tool on this site. So if "sand concentration" is your big thing, why not give it a try? etc etc etc.

As for Orionsbelt's question about "the whim of a met man" versus a "proven computer model", I think you'd have to be incredibly naive or an uber-conspiracy theorist to side with the "whim" theory. But if you want, why not defy the orders, jump in a plane and see what happens. If your engines stop, the model is proven.

Or search for the word "muck" on this site and see what you find.

As someone else put it earlier, "What is the safest course of action here?"

And another thing: Just read a post about the BA flight that lost all engines many years ago. How dangerous can it be, asked a poster. They got all the engines going again. Hmm. Yes. But I don't think they did a 60 minute turnaround when they got to their destination. Airlines can't afford to inspect their engines after every flight, never mind fix/replace them.

Last edited by Dave's brother; 18th Apr 2010 at 09:24. Reason: And another thing...
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Old 18th Apr 2010, 09:19
  #903 (permalink)  
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Sand storm V Volcanic Ash


I can directly answer your question about sand storms v volcanic ash.

Sand (in its many forms) really has only effect on the engine. Abrasion.

Volcanic Ash is 'harder' than sand, and has sharper edges therefore dramatically increasing the abrasive properties of the particles. Over time, this abrasion will render an engine U/S. How much time? we don't know yet hence the problem.

The bigger problem with the Volc. Ash, is that it melts inside the combustion chamber turning to a fluid. When it cools, it forms on the surfaces of the engine causing blockages of cooling holes and veins, imbalancing of rotating parts etc.

Since the turbine engines operating temperatures reach far beyond the melting point of metal components within the engine, when these cooling holes and veins are blocked, the engine fails soon thereafter.

You don't get this problem with a sandstorm.

In Germany, we have the airspace open above FL355. no one has used it yet and sadly i think more of the same tomorrow and tuesday too.

Lets all just hope, and pray if you are so inclined that this disaster is over sooner rather than any kind of later.
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Old 18th Apr 2010, 09:20
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So I think it should be a commercial choice to fly or not to fly as engines will last maybe only 3000 hours on wing rather then 5000 hours but there is no immidiate danger!!!
I hope they last a darn site longer than 5000hrs!
The build up that welds itself onto the turbine blade surface is not such a problem except for the reduction in efficiency and an increased fuel burn. The major problem lies in the build up inside the blades that blocks the cooling holes and leads eventually to a burn through.
The effects on the rest of the airframe: Pitot static port contamination and the effects of erosion (sandblasting!). Plus of course, if it should rain it turns nicely acidic!
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Old 18th Apr 2010, 09:23
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so when HEATHROW DIRECTOR says.....not with me on board..... GOOD get back to West Drayton and do the job that you are actually qualified to comment on
Global Warrior...

A) We're not at West Drayton anymore
B) Unless your area of expertise is volcanoes, then you are no more qualified than any other aviation professional to comment on this situation.
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Old 18th Apr 2010, 09:23
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Mr. Camel: Stereotyping will not help here, it only offers some insight of your thoughtprocess...

Simonpro: The KLM testflight was conducted from SFC to max Level and back down, to cover all levels. And it fits the profile of a normal short haul flight. Maybe you wouldn't be able to go all the way to FL410, but a "normal" jet should make FL 350 in any case (I said normal, not BAE146!). So passing through the 20's will take about 5 minutes on the way up, and another 5 on the way down. At least in what I fly.
LH reports not even a scratch found on the paint, nothing in the engines on a 40 minute flight MUC - FRA at FL240. According to Spiegelonline not even a Metballoon has been launched so far in Germany and all the predictions are calculations by the Volcanic Ash Center in London, not real meassurements.

I am beginning to think that the problem is overrated!

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Old 18th Apr 2010, 09:24
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@ ChalfontFlyer ...
Worth just noting this morning that whilst the vast majority of airlines are currently unable to operate wthin the British Isles, it is possible to fly between the islands in the Channel Islands where both Aurigny & Blue Islands are continuing to operate their schedules.
Aurigny operate piston engined BN Trislanders at around 1500' on the short [20-30nm] hops between the islands.
Blue Island operates a variety of types, but I suspect they are using their Trislanders on inter-island hops as well.

Not exactly in the same league
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Old 18th Apr 2010, 09:24
  #908 (permalink)  
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Ferry flights again

Another B739 (positioning?) landing EHAM now. Presuming that they are on IFR, it would appear that some State/regulator are now opening the door (airspace) to serve, perhaps, some private bodies. It means that within 5 hours all operators will ask the same thing to fly aircraft with or without pax. Maastricht has officially reopened its airspace above 355 as per CFMU portal site. Does KLM operates in VFR and who does exactly control these flight. Some live feeds indicates that the callsign is as KLM and not the reg nbr. Any info on this please.
Btw there are rumors, Sigmet, that the Etna has just waken up this morning.
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Old 18th Apr 2010, 09:24
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Test aircraft theory

A quick thought on sending aircraft up to measure this and that and measure turbine wear and damage.

1. It appears its hard to measure quantities from what I've read on here so far but I have no idea about the subject, and furthermore, no idea if the people's comments I read had any idea or not.

2. The concentration of ash in a particular part of the sky is changing second by second. So really what good is any data that is collected. In 4 hours time, it could be vastly different turning a 'safe' zone into something worse.
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Old 18th Apr 2010, 09:24
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Activity Has Ceased

I would have thought the fact that the VOLCANIC ACTIVITY HAS CEASED (at present) would be of interest.
If this is considered irrelevant, then please pardon me.

Repetition of info already posted seems to be of interest though.
Have tried to post twice in the last 10 minutes, but the post has not shown.Here it is:


all quiet on the western front, at present . .

Maybe itís deemed not worthy.Sorry.

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Old 18th Apr 2010, 09:25
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We no longer have Nimrods. They were grounded forever last month.
Having said that, if they need some aircrat airborne to assess the long term damage to engines, they might as well get them airborne again since they were going to the scrappy anyway.
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Old 18th Apr 2010, 09:27
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It's not looking good for anyone right now, but some of us on the ground have already been affected. I along with many others am into our third day of no work and hence no pay, the joys of agency work! Still the gardens looking nice
Good luck everyone.
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Old 18th Apr 2010, 09:28
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You mean instead of the usual 40.000+ hours on the wing.
Cough !

In your dreams.. ever heard of an LLP data sheet?

Know what Time and Cycle limited apply to to the disks, shaft, bearings etc etc ?

What do you think happens when an AD or SB is due ?

Last edited by Bruce Wayne; 18th Apr 2010 at 09:42.
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Old 18th Apr 2010, 09:28
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3000 people are killed on UK roads every year, not day - 2% of the population per year might cause a complete shutdown of the road network! Just like one volcano related aircraft accident would cause a complete shutdown of airspace - something the authorities do not want for obvious reasons.
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Old 18th Apr 2010, 09:30
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I mean , the market is still there , flights have to be flown , only the revenue is missing for a few days / weeks.
There will be a tremendous backlog of people to move once the dust has settled. I have a colleague in Shanghai who was supposed to fly yesterday. The earliest they could rebook him is the 25th April. He has status on that airline and so they were looking after him. Other people on the same flight were being rebooked on May 10th!!! I have also heard that warehouses are full of freight that isn't being moved and all this stuff will also need to be shipped.

When all this is done and dusted it will probably be all hands on deck. I can imagine that some of you will never have worked as hard in your lives. Let's all hope that is sooner rather than later. In the meantime...best of luck to one and all!
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Old 18th Apr 2010, 09:30
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Reply to MPN11 (post 898) - But at least it's giving them both the opportunity to generate some much needed revenue in these very difficult times!
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Old 18th Apr 2010, 09:37
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Hello JetII

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Old 18th Apr 2010, 09:38
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I love the way everybody jumps onto the engine damage bandwagon whilst totally ignoring the dangers involved with the total blockage of the pitot static system. Especially after the Air France event that could have been caused by a similar situation albeit rapid ice blockage. I admit fully that damage to the engines is extremely concerning the other dangers are no less worrying!

Whilst we train regularly with volcanic ash encounters, leading to unreliable airspeed, in the simulator having to do it for real with a full passenger load is something I would not particularly enjoy!

Pitot heat and anti icing systems won't work for an ash blockage and, as we can't see the clouds/concentrations on weather radar nor do we have any detection instrumentation apart from the unreliable airspeed sop's (which would be pretty much closing the door after the horse has bolted), I think operating commercially would be risky.

Positioning flights with paid professional aircrew ok, passengers? Maybe not.
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Old 18th Apr 2010, 09:39
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Russian and Polish airspace

It seems that most on this forum are ignoring some facts.

Russian airspace and now Polish airspace are open.

President Medvedev is en route to Poland for the funeral.

Have a look at the excellent domodedovo.ru web site (English available)

If the Russian president flies, it might be ok for everyone else to fly. Some attemps have been made on this forum by courageous people to highlight Russian experience with flying in an ash cloud environment but interestingly these comments are usually ignored or very simply commented.

I have the feeling that I am reading a Union forum about eachother's rights and obligations rather than a scientific/engineering debate on how to tackle/deal with the problem.

On the Polish crash forum there was a lot of contributions from Russian pilots, it would be interesting to see their opinion if someone knows how to link up with them. (Please spare me the many derogative/non PC comments about Russians, they are childish at best).
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Old 18th Apr 2010, 09:39
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Just been reported that the upper level winds are unlikely to change direction until later in the week.......
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