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Ash clouds threaten air traffic

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Ash clouds threaten air traffic

Old 21st May 2010, 22:47
  #2961 (permalink)  
 
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Originally Posted by PBL View Post
The "refutation" and "lack of re-refutation" have no more status than the original rumor. For hobbyists, this might be enough. For many professional purposes, it does not suffice.

PBL
This looks to be an official note on the incident - I think someone already posted it ealier:

CEN10RA135 Note the date of the incident - it's pre iceland VA.

I doubt there have been two uncontained failures like this on the same type in less than three months (or rather, if there had I think it would have been bigger news and we'd know).

PBL: From this incident note and your professional contacts you may be able to confirm the details and tie in the photos - in which case the date and location rules out VA.

This may be as close as the rest of us amateurs get to an official statement (reported statement form Cessna): Engine Damage Not Caused by Volcanic Ash: AINonline.
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Old 21st May 2010, 23:10
  #2962 (permalink)  
 
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Latest update from the Iceland Met Office and Institute of Earth Sciences indicates that the explosive activity has died down considerably.

Articles < Seismicity < Icelandic Meteorological office

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Old 21st May 2010, 23:17
  #2963 (permalink)  
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at high thrust, low level, which bears no resemblance to the civil jet environment
Well except take offs, up to 10 a day for some of our aircraft, and go arounds.

And how can you say "no doubt" at low altitude and high thrust?
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Old 22nd May 2010, 01:38
  #2964 (permalink)  
 
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I keep saying that the volcanic conditions that we speak of today "will" result in some measurable degradation of safety but no more than the typical risk that we operate within everyday for all other causes (risk is never zero but it is managed within acceptable limits)

Most readers have no idea of what risk is allowed to underly each and every flight and the variable contributions of the causal factors versus time. Just because you identify a newly recognized causal factor "du jour" doesn't mean that you have to manage it to zero to justify to keep flying.
Lomapaseo

This is a well written and thought If you want zero risk DONT Fly.

There are far more PROVEN risky elements to flight than Ash yet ASH has cought the public imagination hyped by the media amd reacted to by a whole host of back watching Burocrats and quangos.

We have had many fatal landing and takeoff accidents in strong winds and shear conditions even within the "accepted operational levels" but do we have a long thread like this one demanding all takeoffs and landings should only be with zero wind?

Ash which has NO fatality record throughout aviation history has been hyped into a monster or bad wolf which is out to get you.

Maybe its becuase aircraft have always avoided flying through dust, certainly when they do, in certain concentrations its got very very expensive and dangerous. And VA is not the same from all eruptions, some, like this, are far more damaging.
Peter We

Volcanic eruptions are nothing new. Jet aircraft 20+ years ago had hardly any sophisticated equiptment and NO fancy computer generated Ash Prediction charts.

Maybe they flew through low level ash concentrations and never knew about it. If you cannot see it it wont hurt you.

Volcanic Ash really isnt a new phenomina!

Our MEDIA HYPE driven, paranoid, liability and blame culture IS!!!

Oh well off to bed so I can dream of shooting and killing a few million birds to save us from Bird flu!

but more likely to save us from ingesting them in our jet engines a real ignored threat.

Pace

Last edited by Pace; 22nd May 2010 at 06:42.
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Old 22nd May 2010, 06:16
  #2965 (permalink)  
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Originally Posted by if789
This looks to be an official note on the incident - I think someone already posted it ealier:

CEN10RA135
Thanks, IF! Yes, brother forget posted it earlier, along with a quote, and I missed it (the quote distracted me).

The pictures show an aircraft with a D-reg (can't see other letters), with engine, rear fuselage and tail markings identical to those on pictures on the WWW of some other Citations from Eisele Flugdienst. So I can call up the BFU, or indeed the company, and find out.

PBL
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Old 22nd May 2010, 09:18
  #2966 (permalink)  
 
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I guess that a whole lot of the 'Ash Emergency' reporting from the Meeja generally is examples of 'Never let a Few Facts get in the way of a Good Story'.

Even the Flightglobal story reporting no significant damage to the F-18 engines, with a by-line of 23/4/10 was followed the very next day in the same magazine with 'Europe's volcanic ash response: was it adequate?' which mentioned the original 'reported' F-18 damage but not, strangely enough , the previous day's 'no damage' story. I haven't ploughed through the literally 100s of VA references just in Flightglobal to try to judge their attempts to balance what was published but my guess is that they were also to some degree cheerleaders on the 'High VA risk - We're all gonna die' bandwagon. Given Flightglobal's position as an industry-specialist publication and particularly its own masthead (Serious about Aviation), this is disappointing.

It would be a bit of a stretch to envisage a conspiracy in which someone hijacked the NTSB website and planted a faked-up story about the Citation CJ incident so as to place it well before VA became an issue!!!
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Old 22nd May 2010, 09:44
  #2967 (permalink)  
 
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BrookSJG

That is the sickening thing with the media they create the story they want and either ignore the facts or worse falsely make one thing appear to be another.

There are people who have had their lives ruined by the media by pretending something is true and painting a false picture to influence readers into believing it is true. Some of these people have been accused of horrendous crimes. When the courts find them not guilty that report gets a half inch column in the depths of the media report.

It is the same with this charade very damaging to aviation and made up of selective and false reporting designed to generate unfounded fear in the public.

These people including a select few in this forum should be ashamed of themselves as all they achieve is damaging an industry and peoples livelyhoods by their false representations. Worst is most dont even know what they are talking about.

Pace
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Old 22nd May 2010, 10:15
  #2968 (permalink)  
 
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Interesting to see the nature of this ash, note the chunky structure.

Eyjafjallajökull ash under a petrographic microscope in crossed-polarized light at ~40x. Image by Erik Klemetti.



Eyjafjallajökull ash under a petrographic microscope in crossed-polarized light at ~100x. Image by Erik Klemetti.





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Old 23rd May 2010, 17:34
  #2969 (permalink)  
 
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Icelandic Met Office reporting marked decrease in activity:
The eruption activity is minimal and therefore no significant ashfall is expected. The volcano is still being monitored and an ashfall forecast will be issued if neccessary.
Visibly very different!
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Old 24th May 2010, 00:07
  #2970 (permalink)  
 
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VA forecast accuracy

Now that the dust has settled (at least for the moment!), has anyone seen any proper explanation (especially from the Met Office) for the overall lack of accuracy of VA Forecasting and, in particular, for the error(s) that led to the sudden and very obvious revision between 0600 and 1200 last Monday (17th May)?

Quite apart from the disruption caused by lack of inbound flights to LGW and other short-term problems, there was also a potential risk (already mentioned above) from reassignment of certain areas of the North Sea from 'white' to Black in the same revision.

Superficially, it looked like inaccuracies in weather forecasting had been allowed to 'bleed through' into the VA Forecast, with no later corrections being applied as real weather data superseded the forecasts. I have no actual evidence of this but unless something like this occurred, how could such a major restatement of the position of the ash cloud ever be required? - unless, of course, there were other problems with the model that only came to light over the weekend 15/16th May.
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Old 24th May 2010, 06:25
  #2971 (permalink)  
 
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BillS

No, visibly is exactly what the report is saying... there is visibly only steam production, and other signs show that the eruption calmed down... How long, it's impossible to know, though. You can hardly see it on the cameras. Let's hope this is it!
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Old 24th May 2010, 09:07
  #2972 (permalink)  
 
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I have no actual evidence of this but unless something like this occurred, how could such a major restatement of the position of the ash cloud ever be required? - unless, of course, there were other problems with the model that only came to light over the weekend 15/16th May.
There was nothing wrong with the model or the forecasting, they were obviously told to change it, by the new government, to allow the airports to open.
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Old 24th May 2010, 10:43
  #2973 (permalink)  
 
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There was nothing wrong with the model or the forecasting, they were obviously told to change it
errrr....

The Powers That Be can (easily) change the specified minima/maxima for any given situation, so long as the new value remains inside other legal / regulatory limits that may apply. They already did this - by going from 2000 to 4000 micrograms/cube (with additional caveats). They did not need to get the VA forecast 'adjusted' as well. IMHO it would have been extremely foolhardy to even try to do so: someone could easily have other, more accurate evidence and/or might want to saddle the originator of the request/order with all the responsibility (and potential blame). In this situation, a leak to the media would be a virtual certainty! For a recent example of this, see Climate Change 'emails scandal' at the University of East Anglia. A bit of tinkering with climate data and months later, after an external enquiry and at least one Severely Career-Limiting Move, they're still chipping brown solids off the fans! Especially with this recent example to learn from, I'm surprised the Met Office has so far failed to come clean about the forecast!

So why were the limits and the VA forecast both adjusted, at very similar times?? (I still favour cock-up over conspiracy but have no better information myself.)

That said, it's also quite entertaining to watch the various regulators' heads popping above / below the parapet, depending on whether they reckon they'll catch blame (or have to take responsibility!) if ultimately something goes legs-up.

Last edited by brooksjg; 24th May 2010 at 11:19.
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Old 24th May 2010, 11:43
  #2974 (permalink)  
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Peter - there most certainly did appear to be a forecasting error. As brooksjg and I have pointed out, there was a sudden shift of the 'black ash' area from over the middle of England out into the 'clear area' where unsuspecting a/c had been happily toddling along.
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Old 24th May 2010, 12:26
  #2975 (permalink)  
 
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Think about it. The VAAC issue one forecast every 6 hours, and if we examine these forecasts since the beginning of the 'ash crisis', let's say 60 days ago, then there is only this one obvious error on May 17th.

60x4=240 forecasts. One of which is wrong, that's 0.4% of the total. Not a bad accuracy level, to be honest.


Forecasts will always be slightly wrong. The forecast you see on something like the VAAC is merely the most probable outcome. The prediction system typically generates a number of possible forecasts and assigns a probability to each that determines how likely it is to occur.
Perhaps on the 17th there were two with very similar probabilities, and the VAAC staff got unlucky and chose the wrong one. Or perhaps they chose one that was very likely, but for some reason one of the more unlikely predictions turned out to be true.
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Old 24th May 2010, 12:52
  #2976 (permalink)  
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Not that simple, Simon (as they say.). The 'incorrect model' went on for days, drifting the ash down to where it wasn't. Suddenly when a huge fuss erupted - bingo!

A touch more than .4% - and that is assuming that the previous ash disposition charts were all spot on!
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Old 24th May 2010, 15:43
  #2977 (permalink)  
 
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60x4=240 forecasts. One of which is wrong, that's 0.4% of the total. Not a bad accuracy level, to be honest.
Yes, and by coincidence the 'error' happened to close down the major SE airports. Fixing it allowed them to re-open.. what an amazing piece of luck.
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Old 24th May 2010, 16:13
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Yes - not necessarily one 'incorrect' forecast - a whole series of totally consistent forecasts, over at least 3 days, showing movement South / South-eastward and gradual expansion of the cloud's area.

I'm just digging back through the raw mapping data to try to understand better what happened......
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Old 24th May 2010, 21:53
  #2979 (permalink)  
 
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Frankly, as I've said before, I thought the whole event has been handled very well. There will undoubtedly be review and analysis of what could have been done better, and of course with 20/20 hindsight there will undoubtedly be room for improvement.

However that does not change the fact that a response to an unforeseen event - the possibility of a major volcanic ash cloud disrupting the worlds busiest intercontinental air routes, has been handled very quickly, considering the coordination required, with minimal disruption to the travelling public.

Well done to the industry as a whole! You are in a better armed state to face the next challenge when it arrives.
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Old 24th May 2010, 22:45
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You are in a better armed state to face the next challenge when it arrives
Based on most recent events, I beg to differ. We're more likely at a 'Rumsfeld Moment', when it's become apparent that there are some extra Known Unknowns which either didn't matter previously or were Unknown Unknowns.

Realities are that a (small) volcano has stopped erupting for now and the big one (Hekla) has yet to start. Meantime, we still have no quick, accurate means to locate and measure volcanic ash in the atmosphere, and therefore depend on computer modelling, which in turn depends on accurate data from forecasts and actual weather in the recent past. As was demonstrated last week, modelling can fail and each time it does the unnecessary financial cost to the industry is very large and/or aircraft could be damaged.

Not much of a moment for congratulations. And to say that we're 'better armed' only applies to defensive reaction time when ash is predicted, with little improvement in prediction accuracy or avoidance of the problem. There must be potential improvements in sensors and other detection strategies but little evidence at the moment of any concerted effort being applied.

Sorry to rain on the parade but that's the way it is.
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