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Ash clouds threaten air traffic

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Ash clouds threaten air traffic

Old 21st Apr 2010, 16:29
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Looks to be getting pretty active again in the past few hours, this morning it was only a very small amount of cloud around it. Third picture down

Link: Mulakot - myndavelar
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Old 21st Apr 2010, 16:36
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Let the Great Experiment begin...

Officials say 90% of flights will be operating at Heathrow by 1500 today and service should be at 100% by Thursday. However, that figure includes only regularly scheduled flights, not efforts to clear up the backlog of passengers.
How can this be when the CAA's Revised Airspace Guidance last night requires airlines to:

· conduct their own risk assessment and develop operational procedures to address any remaining risks;
· put in place an intensive maintenance ash damage inspection before and after each flight; and
· report any ash related incidents to a reporting scheme run by the CAA?
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Old 21st Apr 2010, 16:37
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perhaps better characterized as limited or minimal damage.
Depends on the viewpoint; turbine bucket with ash sticking to it does not affect engine performance much. Replacing or scrubbing it might prove costly and time consuming.

Yes I did my "test" flight, thank you for asking.

Ever helpful ATC confirmed that my penetration of VA alert area was solely upon my discretion. I would have appreciated that even more, if they choose some earlier moment to tell me that than post-landing taxiing.

No, the engines did not flameout, stall, show glowing around intakes or props, spout fire from exhausts or increased their respective ITTs erratically & rapidly. There was no st Elmo's fire visible on the screen, it was noon anyway, and no strong sulfuric odour was present.

As I have made the post-flight written confirmation of the above mentioned facts, the maintenance stated that just flying through suspected VA contaminated area does not warrant complete post VA penetration maint procedure and cleared the machine for further flights.

At least now I won't get the bill if the overhaul comes before planned time.

Regarding see and avoid: in severe CAVOK one can discern layers of dirt in the atmosphere. Now I know what I've seen yesterday over mid Italy - it looked exactly as photo on the page 3 of German Falcon flight report. There was no practical way of going around this one, it stretched from the horizon to horizon. And I can tell that regarding my routing, Met office's prediction of VA spread was frighteningly correct.
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Old 21st Apr 2010, 16:43
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are you saying they are not following the CAA guidelines ?

doesn't it say if an aircraft flies into a low ash density area that damage inspection has to occur after the flight ?
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Old 21st Apr 2010, 16:50
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Met office report Northern Ireland 1400 BST — ash layer around 8500 ft, at least 500 ft thick - visibility greatly reduced with a strong sulphur smell.
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Old 21st Apr 2010, 17:03
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Unconfirmed: Source BBC.

BBC reporting that pax from QF32 ( Heathrow - Singapore ) are contacting them. Flight is boarded but holding pax on the ground pending an improvement in the "air quality ". The skipper is telling pax that the ash concentration is above the levels in which Qantas are happy to fly.
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Old 21st Apr 2010, 17:06
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are you saying they are not following the CAA guidelines ?
No - we're not regulated by the UK CAA anyway and they did they homework; risk was assessed , procedures put in place after liaising with local CAA. Leading edges, props, engine intakes and transparencies were checked for abrasion damage or dust accumulation. None was found and acft was returned to service. Legal - yes, sufficient - couldn't say.
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Old 21st Apr 2010, 17:08
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Clandestino - thanks for the clarification - makes sense.

btw I'm glad flight wasn't eventful for you.
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Old 21st Apr 2010, 17:32
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A Tough Decision?

Rab-K - Your earlier post is twaddle. BA would not have just kept flying from day 1. After 5 days on FIR closure a DECISION needed to be made. Keep up the same position or open airspace. It's far easier to close it on safety grounds than open it on the same. But at some point a decision needed to be made. If WW helped get that one way or the other then good.

Inaction and hesitation are no more the friends of safety than knee-jerk, just do-it are. After 5 days and most EU FIR's starting to operate the UK was in danger of being the 'first ones in and the last ones out'.

And anyone who thinks that commercials are not heavily in play on all of this are much mistaken. No Buck, no Buck Rogers as they used to say in Flight Test.

As I said, I'd sooner have people who step up to the plate and make a decision than keep examining their naval fluff until someone else makes the decision for them.

We didn't go to the moon by waiting for the all clear from every quarter let alone getting to and from JFK. 'Decision height'. Captain Walsh called it.
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Old 21st Apr 2010, 18:23
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HIAL have just (16:00) announced that all HIAL airports north of Inverness (including Wick, Kirkwall & Sumburgh) are closed due to a volcanic ash cloud. Next update will be at 18:00.

HIAL update at 19:00 - airports closed until Thursday morning.
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Old 21st Apr 2010, 18:24
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Volvo_Aero about Ash

Volvo-Aero has a short piece about ash in their jet engines, see the following url:
Actual - Actual : Volvo Aero
In princople they state that their engines can stand rain, ice and some birds, but not ash.
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Old 21st Apr 2010, 18:30
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Someone was asking for mass-flow numbers earlier on. RR's Web site gives an intake mass-flow for the RB211-535E4B (I picked an engine arbitrarily) of 1,177lb/sec or 533.87kg/sec.

Based on the figure of 0.3 milligrams per m3 given for Stranraer, at an air density of 1.2kg/m3 at sea level (obviously we're not interested in sea level, but at least it's wrong in a known way - the ash measurement is a sea-level one and I guess RR's figures are test-stand measurements, so it's consistent) that would be 444m3 of air a second and 0.133g of ash a second - 478g of ash per engine-hour.

(Although, the -535 is a very high bypass turbofan, so perhaps we need the core mass flow...)
One can simply divide by the by-pass ratio of 4.3.

But there is the issue, under which conditions is the mass flow rate 1177 lb/s? We probably should consider a density figure at pressure and temperature corresponding to a typical cloud level. You can take standard atmosphere data etc.

However there is another estimate, based upon speed and diameter. Take the fan diameter, 74.1 in. Calculate the area. Divide my the by-pass ratio. If I do that, assume a speed of 180 m/s, for 0.3 g/m3, I end up with actually a very similar figure, 126 g/hour (assuming no algebraic error...) Of course one would hope crossing an ash zone would take less than an hour.

(From peter_we)

Thats a pretty high level.
BTW, indeed the new threshold figure of 2 g/m3 comes across as not very conservative. I would have expected them to pick a figure more like 0.5?
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Old 21st Apr 2010, 18:51
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A Danish perspective on detection ...

More accurate mapping of ash cloud with Risø DTU?s wind energy measuring equipment
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Old 21st Apr 2010, 18:53
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tolerance levels

In the UK MET charts posted by kyloe (#2186) the black area according to the label is the zone "that exeeds accepted manufacturer tolerance levels"

I´ll appreciate if somebody can give me the figure for that level.
¿some ash concentration? ¿An envelope for all turbines?
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Old 21st Apr 2010, 19:03
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Here´s a link to new hi-res pictures of the Hornet engine published by the Finnish Air Force today:

Puolustusvoimat - Frsvarsmakten - The Finnish Defence Forces

Like has already been said, no significant damage was found, only "concentrations of foreign materials", partly melted, but it´s plain to see that these spots do not even come close to blocking any of the cooling holes in the turbine blades. On the other hand, the occurrence took place in the morning of the 15th, before any restrictions even had been put in place.
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Old 21st Apr 2010, 19:11
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I am amazed at the amount of people looking for heads to roll when all those heads did was follow the rules.
I almost wrote, "Surely not the Nuremburg defence", but decided against. Instead may I refer you to the following quote:

Rules are for the guidance of wise men and the blind obedience of fools. (Solon, the Lawmaker of Athens, d. 559BCE)
Actually I think it was Douglas Bader!

As others have pointed out, there was obviously a problem with the rules. There is never zero volcanic ash in the atmosphere. We have always coped around the world until an invisible plume hit the UK. Thank heavens we have leaders like Captain Willie Walsh to sort things out.



Last edited by Stoic; 21st Apr 2010 at 21:37.
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Old 21st Apr 2010, 19:16
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Forecast models and charts fairly consistent on a gradual change to southerly winds, at least over the UK, overnight Friday/Saturday,

UKMO surface charts to T+120
Metbrief - Met Office Analysis and Synoptic Weather Forecast Charts via Wetterzentrale

300mb forecast charts to T+120 (rh side of page)
CRWS Jet Stream Forecast Map Menu

Here's hoping those lows approaching from the SW are more vigorous than forecast.
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Old 21st Apr 2010, 19:20
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I think the argument was more about to many cooks and the fact that the tests needed to relax the "rules" could have been done days ago if what was said on the BBC was anything to go by.

Another reason why there has never been a statue made of a committee

Yes there will be a big row over who pays and maybe with some justification an expensive lesson to be learnt all round


Last edited by Pace; 21st Apr 2010 at 19:41.
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Old 21st Apr 2010, 20:11
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The number of pompous punters here who are outraged that airspace was closed at all because the problem doesn't really exist is irritating.

The number who wonder why "tests" weren't done immediately is frightening.

The number who believe that the Government vacillated over decision making after tests and consultation is mind boggling.

Let me make a number of things quite clear.

1. The problem is real. Yes, I know volcanoes erupt all over the world. I know that there are sand storms in the Desert and dust in the air. I know intrepid pilots fly around erupting volcanoes. I know that some European airports remained open. The problem however is that this particular dust from this particular volcano thanks to this particular weather system stuck itself in large quantities over Britain, and it has the capacity to bugger up very expensive jet engines that are not quickly replaceable by the manufacturers. I know you paid your Twenty quid to get to Paris, but I am not going to risk wrecking Ten million dollars worth of engines to get you there today.

2. Tests were done immediately. Do you think the Government keeps a jet already wired up and on standby to test for volcanic ash? Is there a submarine kept ready and waiting to check the ocean floor for undersea earthquakes? Of course not. Tests were carried out. Did you know it takes time to design a test? It also takes time to prepare for a test and then analyse the results.

3. Vacillating Government? Tests had to be done. Manufacturers had to be consulted. The results of the tests had to be analysed. There are also regulatory frameworks that must be followed because they have the force of law. This takes time. Do you expect the Government to take a billion dollar bet without proper advice, just so that you can get your sorry backside to Amsterdam to smoke dope? I happen to think that Five days from whoa to go is a pretty snappy response where a technically, scientifically and operationally complex decision has had to be made.

Furthermore, next time the airspace is closed again because of this or other eruptions, you will have no further grounds whatsoever to complain.

Thank you to the person who posted the high resolution images of the F404 nozzle guide vanes and first stage blade. I have to take issue with your view that there was "no damage'. To make that statement would require the sectioning of at least one each of those hollow components to see what has been deposited internally, as it is internal build up that will have the most effect on blade and vane cooling.
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Old 21st Apr 2010, 20:19
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Clear blue skies.

Hi Sunfish

The problem is that for the past week in the UK we have had brilliant, clear blue skies. In 1940 we had the same. Then the sky was full of aeroplanes. Our parents called it Battle of Britain weather.

This past week the sky has been empty of aeroplanes. Brilliant, clear blue skies. Volcano weather! Well, that is how I shall remember it.


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