Ash clouds threaten air traffic
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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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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.
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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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!
). 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!
60x4=240 forecasts. One of which is wrong, that's 0.4% of the total. Not a bad accuracy level, to be honest.
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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......
I'm just digging back through the raw mapping data to try to understand better what happened......
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.
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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You are in a better armed state to face the next challenge when it arrives
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.
Brookes:
If you want to attempt to forecast where ash is, then your industry can pay for it.
Meanwhile, in Two weeks from the start of the event, the airframe manufacturers, engine manufacturers, airlines, regulators, lawyers, vulcanologists, meteorologists and insurers of many nations worked together to produce a set of operational protocols that worked.
I'm sorry if they weren't to your liking, but the fact is that they are an achievement and can be deployed again if necessary.
Bear in mind that the consequences of a major part of the Transatlantic fleet, for want of a better word, getting their engines seriously damaged by Ash ingestion would have been months of cancelled flights as there is not enough engine overhaul capacity on this planet to deal with an emergency workload of that magnitude.
We cater for the odd bird strike, not 200+ airliners needing four overhauled engines at five minutes notice. Please try and understand that that is the logistical nightmare behind the need for regulation and prohibition.
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.
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.
Meanwhile, in Two weeks from the start of the event, the airframe manufacturers, engine manufacturers, airlines, regulators, lawyers, vulcanologists, meteorologists and insurers of many nations worked together to produce a set of operational protocols that worked.
I'm sorry if they weren't to your liking, but the fact is that they are an achievement and can be deployed again if necessary.
Bear in mind that the consequences of a major part of the Transatlantic fleet, for want of a better word, getting their engines seriously damaged by Ash ingestion would have been months of cancelled flights as there is not enough engine overhaul capacity on this planet to deal with an emergency workload of that magnitude.
We cater for the odd bird strike, not 200+ airliners needing four overhauled engines at five minutes notice. Please try and understand that that is the logistical nightmare behind the need for regulation and prohibition.
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If you want to attempt to forecast where ash is, then your industry can pay for it
So what about ash detection? Seems that the only really effective method is to fly an aircraft along a track where VA might be and use lidar and / or sampling to check what's there.
Cost? Really doesn't matter! NOT doing this results in potentially unnecessary shutdowns of airspace, airports and sometimes the whole of UK air transport, with calculable cost x per hour or day. So long as the cost of an accurate forecasting / alerting system is less than a fraction of x, it's worth doing. (fraction calculated from the probabilities of future eruption(s) and of false VA alarms.)
Risk? You can't ask people to deliberately fly research aircraft into high risk areas when there is no accurate VA data.
However, there is a suitable platform for doing just this, at negligible risk to people. Predators with all sorts of fancy sensors (and Hellfires!) are already flying reliably in various places. Why not rip out as much of the expensive bits as possible from some Predators (or another suitable UAV), plus whatever classified bits have to go, mount instead some suitable LIDAR, SO2 sensor and whatever other sensors and samplers would be useful, plus civil transponders, and use them as a picket line somewhere off NW Scotland / Ireland? Flying orbits using (say) 4 aircraft round the clock at various heights in an otherwise-vacant bit of airspace would yield very accurate data on what was heading towards UK. If all else failed, monitoring the in- and post-flight engine condition of the engines would also provide good data.
Why not? - We'd only need to fly the picket line as such when we knew that an eruption was happening. We know where the risk will be coming from. Rest of the time, the UAVs could be used for (military) training in the use of the UAV platform and occasionally checking that the system worked with a quick trip close to a volcano.
OK - would not prevent disruption altogether but would minimise it. And much better than doing nothing proactive!
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Originally Posted by brooksjg
Risk? You can't ask people to deliberately fly research aircraft into high risk areas when there is no accurate VA data.
If this is considered acceptable why not fly samplers in the areas where the ash 'isn't' to confirm the forecast?
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Sunfish: We cater for the odd bird strike, not 200+ airliners needing four overhauled engines at five minutes notice. Please try and understand that that is the logistical nightmare behind the need for regulation and prohibition.
Brooks:
Off you go then and develop your little program and pay for it yourself. The operational regulations about avoiding ash clouds in real time while maintaining separation standards with other aircraft all doing the same thing should be a highly entertaining read, as will those regarding diversions and emergency procedures.
Your accountants will perhaps chafe a little while these expensive standards gather (non - volcanic) dust sitting on the shelves waiting for the next Icelandic eruption, and if it's a big one from Katla, and the wind is in the wrong direction, then all your little cheese paring standards aren't going to be much use are they? In my opinion, the reaction of the regulators was measured, proportionate, prompt, cost efficient and minimised both risk and disruption to the public to a bare minimum.
SSK:
It is not the job of the Health Department to monitor your personal health either, but when an epidemic potentially occurs the Health Department rightly steps in.
A single engine failure is a matter for your airline. An epidemic of engines all turning up at the "Hospital" at once is a matter of public concern regarding provision of RPT services and hence regulatory action.
To put it another way: An ounce of prevention is worth a pound of cure. Saying "No" and grounding you until we are relatively certain you are safe is the simplest, cheapest and most direct safety action.
Part of the purpose of my last post was to highlight that the industry has done nothing except react 'passively'. Whether this reaction was adequate or technically sound is debatable. Anyway, we have some breathing space while the volcano(es) go(es) quiet and we await the next eruption - expert opinion suggests there will be one, possibly soon.
So what about ash detection? Seems that the only really effective method is to fly an aircraft along a track where VA might be and use lidar and / or sampling to check what's there.
Cost? Really doesn't matter! NOT doing this results in potentially unnecessary shutdowns of airspace, airports and sometimes the whole of UK air transport, with calculable cost x per hour or day. So long as the cost of an accurate forecasting / alerting system is less than a fraction of x, it's worth doing. (fraction calculated from the probabilities of future eruption(s) and of false VA alarms.)
Risk? You can't ask people to deliberately fly research aircraft into high risk areas when there is no accurate VA data.
However, there is a suitable platform for doing just this, at negligible risk to people. Predators with all sorts of fancy sensors (and Hellfires!) are already flying reliably in various places. Why not rip out as much of the expensive bits as possible from some Predators (or another suitable UAV), plus whatever classified bits have to go, mount instead some suitable LIDAR, SO2 sensor and whatever other sensors and samplers would be useful, plus civil transponders, and use them as a picket line somewhere off NW Scotland / Ireland? Flying orbits using (say) 4 aircraft round the clock at various heights in an otherwise-vacant bit of airspace would yield very accurate data on what was heading towards UK. If all else failed, monitoring the in- and post-flight engine condition of the engines would also provide good data.
Why not? - We'd only need to fly the picket line as such when we knew that an eruption was happening. We know where the risk will be coming from. Rest of the time, the UAVs could be used for (military) training in the use of the UAV platform and occasionally checking that the system worked with a quick trip close to a volcano.
OK - would not prevent disruption altogether but would minimise it. And much better than doing nothing proactive!
So what about ash detection? Seems that the only really effective method is to fly an aircraft along a track where VA might be and use lidar and / or sampling to check what's there.
Cost? Really doesn't matter! NOT doing this results in potentially unnecessary shutdowns of airspace, airports and sometimes the whole of UK air transport, with calculable cost x per hour or day. So long as the cost of an accurate forecasting / alerting system is less than a fraction of x, it's worth doing. (fraction calculated from the probabilities of future eruption(s) and of false VA alarms.)
Risk? You can't ask people to deliberately fly research aircraft into high risk areas when there is no accurate VA data.
However, there is a suitable platform for doing just this, at negligible risk to people. Predators with all sorts of fancy sensors (and Hellfires!) are already flying reliably in various places. Why not rip out as much of the expensive bits as possible from some Predators (or another suitable UAV), plus whatever classified bits have to go, mount instead some suitable LIDAR, SO2 sensor and whatever other sensors and samplers would be useful, plus civil transponders, and use them as a picket line somewhere off NW Scotland / Ireland? Flying orbits using (say) 4 aircraft round the clock at various heights in an otherwise-vacant bit of airspace would yield very accurate data on what was heading towards UK. If all else failed, monitoring the in- and post-flight engine condition of the engines would also provide good data.
Why not? - We'd only need to fly the picket line as such when we knew that an eruption was happening. We know where the risk will be coming from. Rest of the time, the UAVs could be used for (military) training in the use of the UAV platform and occasionally checking that the system worked with a quick trip close to a volcano.
OK - would not prevent disruption altogether but would minimise it. And much better than doing nothing proactive!
Your accountants will perhaps chafe a little while these expensive standards gather (non - volcanic) dust sitting on the shelves waiting for the next Icelandic eruption, and if it's a big one from Katla, and the wind is in the wrong direction, then all your little cheese paring standards aren't going to be much use are they? In my opinion, the reaction of the regulators was measured, proportionate, prompt, cost efficient and minimised both risk and disruption to the public to a bare minimum.
SSK:
It is NOT the job of the Regulator to regulate on issues of commercial judgement, which this is. Safety - yes. Logistics - no.
A single engine failure is a matter for your airline. An epidemic of engines all turning up at the "Hospital" at once is a matter of public concern regarding provision of RPT services and hence regulatory action.
To put it another way: An ounce of prevention is worth a pound of cure. Saying "No" and grounding you until we are relatively certain you are safe is the simplest, cheapest and most direct safety action.
Last edited by Sunfish; 25th May 2010 at 21:42.
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regulations about avoiding ash clouds in real time while maintaining separation standards with other aircraft all doing the same thing
I NEVER suggested anything of the sort.
My observation is that the VAAC forecasting can be inaccurate, as was especially obvious on 17th May. There is some technology (UAVs with suitable sensors) that could be used if the airlines wish to avoid losing revenue due to unnecessary shut-downs when in fact there is not enough VA to be a problem (although 'tolerable' ash density presumably still awaits final agreement...) or it's in places where it can have no effect. A way this could be funded is via contributions from companies at risk of major losses due to VA - it's a business calculation for them what measures would be cost-effective. From where I'm sitting, it looks like an excellent investment in the absence of any other improvement to the forecast....
How my suggestion could refer to aircraft playing officially-sanctioned 3D Blind Man's Buff I'm unable to explain! I was only suggesting a method to improve VA mapping, nothing to do with subsequent use of the resulting maps.
It is NOT the job of the Regulator to regulate on issues of commercial judgement, which this is. Safety - yes. Logistics - no.
It is not the job of the Health Department to monitor your personal health either, but when an epidemic potentially occurs the Health Department rightly steps in.
A single engine failure is a matter for your airline. An epidemic of engines all turning up at the "Hospital" at once is a matter of public concern regarding provision of RPT services and hence regulatory action.
A single engine failure is a matter for your airline. An epidemic of engines all turning up at the "Hospital" at once is a matter of public concern regarding provision of RPT services and hence regulatory action.
Just because some suggest that there is an epidemic on the horizon does not mean that it will actually occur (SARs etc.). So like other concerns watching, measuring and a measured response in avoidance seems to be the best action all of which is being practised.
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Sunfish
On what basis or knowledge do you make your fanciful and wild statements?
Frankly Sunfish you do not have a clue what you are talking about.
Do you not think that the Airline industry would not jump at the so called "cheapest" option as you declared?
The biggest flaw in computer mapping of VA is that VA density is no more consistant than any cloud.
You could take an area of 10,000 sq miles of ash contaminated air estimated as being within the approved density levels and there would be NO consistancy in that area.
Some patches would be way below other patches would be way above.
Any particles in the air of enough area and density will show to the naked eye in a cloud or mist form. The only practical and accurate way to avoid flying into dense ash is to avoid flying into visible cloud especially pollution coloured cloud.
Stick in clear air by using the normal CB avoidance of requesting a left or right deviation is the only practical and reliable way of keeping clear of dense ash which "could" cause you an inflight engine problem and of course avoiding flying at night.
As to minute density areas of ash which are in thin mist form or not visible then the only practical way is to check those aircraft for pollution damage on a regular basis.
As for your doomsday scenario forecast of 100s of engines needing major maintenance that is equally fanciful and not showing any evidence to date.
Until the day that qualified engineers start reporting such damage I am afraid that your comments will stay in the fanciful and in your dreams bin.
If that ever happens and I doubt it then I will take my hat off to you and say that Sunfish was right.
I would also like to ask you what your background and knowledge is that justifies your wild assumptions?
Yes I do think the current VA forecasting is seriously flawed and innacurate and that also is proving to be true.
Please also differentiate between what is a threat to flight and a threat to bank balance.
The threat to bank balance will be best determined by the airlines as probably will the threat to flight by pilots and airlines and engineers not some burocrats, politicians or quangos with their own agendas and back covering foremost.
Pace
To put it another way: An ounce of prevention is worth a pound of cure. Saying "No" and grounding you until we are relatively certain you are safe is the simplest, cheapest and most direct safety action.
Frankly Sunfish you do not have a clue what you are talking about.
Do you not think that the Airline industry would not jump at the so called "cheapest" option as you declared?
The biggest flaw in computer mapping of VA is that VA density is no more consistant than any cloud.
You could take an area of 10,000 sq miles of ash contaminated air estimated as being within the approved density levels and there would be NO consistancy in that area.
Some patches would be way below other patches would be way above.
Any particles in the air of enough area and density will show to the naked eye in a cloud or mist form. The only practical and accurate way to avoid flying into dense ash is to avoid flying into visible cloud especially pollution coloured cloud.
Stick in clear air by using the normal CB avoidance of requesting a left or right deviation is the only practical and reliable way of keeping clear of dense ash which "could" cause you an inflight engine problem and of course avoiding flying at night.
As to minute density areas of ash which are in thin mist form or not visible then the only practical way is to check those aircraft for pollution damage on a regular basis.
As for your doomsday scenario forecast of 100s of engines needing major maintenance that is equally fanciful and not showing any evidence to date.
Until the day that qualified engineers start reporting such damage I am afraid that your comments will stay in the fanciful and in your dreams bin.
If that ever happens and I doubt it then I will take my hat off to you and say that Sunfish was right.
I would also like to ask you what your background and knowledge is that justifies your wild assumptions?
Yes I do think the current VA forecasting is seriously flawed and innacurate and that also is proving to be true.
Please also differentiate between what is a threat to flight and a threat to bank balance.
The threat to bank balance will be best determined by the airlines as probably will the threat to flight by pilots and airlines and engineers not some burocrats, politicians or quangos with their own agendas and back covering foremost.
Pace
Last edited by Pace; 26th May 2010 at 00:33.
Nothing I have said is wild or fanciful. I've watched the build of plenty of engines and I assure you it does not happen overnight. Do you know for example what tip grinding is? Do you know how many tip grinding lathes are around? Have you ever seen people at the bench individually hand finishing blades and vanes?
Do you understand that when the evidence of which you speak appears, it is too late for that engine? Don't you understand that engines take a long time to build?
Do you understand the consequences of being wrong and not applying the precautionary principle? I do not think you do.
Do you understand that when the evidence of which you speak appears, it is too late for that engine? Don't you understand that engines take a long time to build?
Do you understand the consequences of being wrong and not applying the precautionary principle? I do not think you do.
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Originally Posted by brooksjg
There is some technology (UAVs with suitable sensors) that could be used if the airlines wish to avoid losing revenue due to unnecessary shut-downs ....
PBL
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Sunfish: Do you understand the consequences of being wrong and not applying the precautionary principle? I do not think you do.
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NASA has posted an example of satellite and lidar observation of ash clouds for 16 May.
As NASA puts it
Nighttime Ash Tracking with CALIPSO : Image of the Day
As NASA puts it
One reason for widespread closures was the challenge in knowing where the ash was. Many satellites can provide a bird’s-eye view (such as the top, nighttime image) that can identify thick plumes of ash, but few satellites can tell how high the ash is in the atmosphere. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite, however, records a vertical profile of the atmosphere, which reveals the altitude of ash clouds, shown in the lower image. These observations help modelers in volcanic ash advisory centers improve forecasting models and issue more accurate warnings to pilots and others with aviation interests.
Nighttime Ash Tracking with CALIPSO : Image of the Day
Your argument is based on an assumption that airlines are too stupid to recognise this, and therefore need civil servants to tell them what they can and cannot do.