Is it safe to fly VFR at the moment?

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Gaznav
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Location: Brackley

Post by Gaznav » Mon Apr 19, 2010 10:41 pm

The hype from the Met Office, NATS, CAA and the Media is all based upon the B747 event in 1982. What they fail to mention is that the B747 flew through the middle of the densest part of the cloud for a very long period, during a dark moonless night and ignoring (through no fault of their own as this was a relatively unkown event) lots of warning signs.

Here is a small portion of the report:
On the clear, moonless night of 24 June 1982, Scheduled BA flight 009 took off from sweltering Kuala Lumpur bound for Australia. There were 249 passengers on board the plane, which was laden with 91,000kg of fuel for the five-hour flight to Perth.

At the controls was Captain Eric Moody (pictured recently). As they levelled out at the 747’s cruising altitude of 11,300 metres, the crew ate their evening meal, just as the flight passed south of the city of Jakarta.

His dinner eaten, Captain Moody left the cabin and made his way down the spiral stairs to the first class section in search of an unoccupied toilet; but before he could find one he was called back. Moody remembers noticing as he turned some little puffs of what seemed to be smoke issuing from vents on the floor. There was also an odour that reminded him of the smell left behind after electrical sparks have flown.

When Moody reached the cockpit the crew had already switched on the seatbelt signs and the engine igniters, to support the combustion of the fuel, just in case. The windscreens were lit up with the most impressive displays of St Elmo’s fire the captain had ever seen. The weather radar, though, showed nothing unusual. Then the First Officer pointed out that all the engines appeared to be lit from within by electrical discharges. In moments, the St Elmo’s fire changed to something resembling tracer bullets. Almost immediately, Roger the Senior Engineer called: “Engine failure number four”.

There was a pause. Then he announced: “Engine failure number two….three’s gone…. they’ve all gone.”

Moody said: “OK Roger, put out a Mayday”.

13.44 “Jakarta, Jakarta, Mayday, Mayday Speedbird 9. We’ve lost all four engines. We’re leaving 370.”
Gary Coleman
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JimCrawford
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Joined: Tue Apr 20, 2010 2:23 pm

Post by JimCrawford » Tue Apr 20, 2010 2:59 pm

To reply to the comment made by Gasax:

>>>>If the Metoffice or NATS had sent a couple of aircraft into the plume and measured it in a systematic way I would believe. Instead we have a computer model and one(?) monitoring flight. And for that we are going to half bankrupt the airlines and when the protests get too loud we can say 'things are getting better'! ( now where did I hear that?).<<<<

There is only one aircraft in the UK, or for that matter Europe, capable of making scientific measurements in the plume and that is the BAeS 146 301 GLUXE operated by the Facility for Airborne Atmospheric Measurements based at Cranfield but operated world wide on behalf of the Met Office and NERC. By the law of $od this heavily instrumented aircraft had just been completely stripped of all scientific equipment in preparation for structural modifications, repainting and refitting for a major role change. Instruments were distributed all over the country at their parent organisations and broken down for the maintenance opportunity. Staff had taken the opportunity to take leave, two are stuck in Denver, one in Borneo
Despite these problems the remaining FAAM staff, and those of Direct Flight (operations) and Avalon (engineering organisation) have managed to refit the aircraft in ~3-4 days. This would normally be scheduled for a months work.
At the time of writing ~13:45 Z the aircraft is heading north past Cape Wrath on exactly the sort of measurement mission that is needed to get hard data to plug into the Met Office computer model.
Makes you wonder what a short uninstrumented flight by BA or other airline is expected to achieve, apart from political pressure.
Visit the website to see the track plot (you may have to register)

www.faam.ac.uk

Jim

Ian Melville
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Post by Ian Melville » Tue Apr 20, 2010 3:18 pm

Er actually they are operating a german registered Dornier 228.

It was on the telly last night
http://www.bbc.co.uk/iplayer/episode/b0 ... Episode_5/

gasax
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Location: Aberdeen

Post by gasax » Tue Apr 20, 2010 8:57 pm

The crux of the issue is that all of the present warnings are based upon computer modelling. I use that in my work and I'm acutely aware that the initial model runs are always - wrong (GI-GO), always conservative and need validation from the real world.

The MetOffice seem to have failed on every count. Excuses about aircraft availability simply highlight the incompetence behind the advice.

The area covered by the model's projections are huge. The density of any substance within that vast area will vary by orders of magnitude - from virtually undetectable to dense enough to make breathing difficult.

So the entire area is prohibited? Yellow tabard and 'elfhin safety gorn mad. There is an obvious answer - simple sampling and mapping - without that they are simply scaring people with stories of monsters under the bed - which naturally you cannot see!!!!!!
Pete Morris
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JimCrawford
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Joined: Tue Apr 20, 2010 2:23 pm

Post by JimCrawford » Wed Apr 21, 2010 3:25 am

Ian, our colleagues using the Nerc Do228 (out of Staverton) are actually using some of the FAAM instrumentation and science staff. A couple of the instruments use common canisters and were 'easily' borrowed. The Do however is restricted in the altitude range it can cover (unpressurised aircraft) whilst the 146 can get much higher and has the capability to drop sondes.
If you looked at my FAAM web link you would see the 146 flight plot in real time.

Gasax, the Met Office modelling for this sort of event is the best avilable and internationally recognised as such. Just because you have difficulty making your models work doesn't mean the Met Office suffers from the same problem. Also the plume predictions and measurements are exactly that - don't shoot the messanger! The aircraft grounding is because the operation is based on zero ash, so you cannot fly public transport if ash is present - you would be operating outside your AOC.

I have had insider information during this event, I'm the FAAM staff member stuck in Borneo :lol: and I can assure you the work done back at base and at the Met Office has been heroic.

Jim

Steve Brown
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Post by Steve Brown » Wed Apr 21, 2010 12:32 pm

Zero ash?

Is that mentioned in this?

http://www.skybrary.aero/bookshelf/book ... dium=email

This refers to IFR clearance but not all public transoprt is under IFR so where are the regs that say no PT unless zero ash

And in order to demonstrate compliance / conform to AOC how does the operator measure that the air is zero ash. ( I'd bet the atmosphere is never zero ash)


Ash cloud = visible
Plume is cloud - outside plume is not cloud

gasax
Posts: 165
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Location: Aberdeen

Post by gasax » Wed Apr 21, 2010 4:44 pm

Jim, given the accuracy of the other predictions from the MetOffice that is little to boast about.

The crux of the issue is that ALL models need real world validation and if the MetOffice cannot do that, their modelling will be hopelessly conservative - that is the nature of modelling!

And we see that events have largely overtaken this conversation with the airlines proving the density of ash is insufficient to cause any damage at all...........................................
Pete Morris
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Bob F
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Location: Cheshire

Post by Bob F » Wed Apr 21, 2010 7:40 pm

Captain Eric Moody, skipper on that 747 flight mentioned above when all 4 engines quit, was on TV tonight & gave the impression "that the present restrictions were a bit over the top". He said it went with the job on the route they flew (South East Asia/Pacific) & there were something like 70 or 90 volcanoes (can't remember which) in that sector.
Bob Farrell
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John Brady
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Post by John Brady » Thu Apr 22, 2010 2:25 pm

I had not found this before but here are the volcanic ash advisories from the met office

http://www.metoffice.gov.uk/aviation/va ... k_vag.html

John

JimCrawford
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Joined: Tue Apr 20, 2010 2:23 pm

Post by JimCrawford » Thu Apr 22, 2010 4:01 pm

Steve,
Forgive my sloppyness equating IFR with Public Transport. I was thinking along the lines that most international flights of the type affected are flight planned as IFR. Can you fly special VFR out of LHR??
I agree that there is no such practical thing as 'zero ash' there is so much activity that there will always be a background level.
A more quantitative measure would be 'what is the number concentration, material type and size distribution which is the maximum acceptible re fan abrasion' and 'what is the number concentration, material type and size distribution which is the maximum acceptible re glassification in the hot end' They may not be the same.
I'm not aware of such parameters. If the engine manufacturers and assorted certification authorities could nail those numbers then the whole fuss would be reduced to go/nogo from in situ or satellite measurements.

gasax,

ignoring the cheap jibe.

>>>>The crux of the issue is that ALL models need real world validation and if the MetOffice cannot do that, their modelling will be hopelessly conservative - that is the nature of modelling! <<<<

exactly so, that's why so much effort was expended in getting the 146 on task. Indeed a large proportion of the 146 tasking is model verification in support of MetO and University research groups.


>>>>And we see that events have largely overtaken this conversation with the airlines proving the density of ash is insufficient to cause any damage at all<<<<

Proof??? I wasn't aware of any quantitative measurements made on those flights
Any damage at all??? measured by what critera?

gasax
Posts: 165
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Location: Aberdeen

Post by gasax » Fri Apr 23, 2010 8:38 am

As for cheap jibes - you started them if you care to read your own post!.

People who make extragant claims worry me in any technical area - it demonstrates an attitude inappropriate in anything other than marketing.

In this case where the uncertainties are greater than any of the variables the absoulte statements from the MetOffice and NATS were obviously completely inappropriate.

Trying to get the aircraft to work - very worthy. Trying to act like King Canute - results in wet feet and red face.
Pete Morris
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