We live in a litigious world, and I believe that becomes a strong factor for many decisions. Furthermore, once a decision has been made to restrict traffic, there may be some reluctance to lift it unless the evidence is compelling - hypothetically speaking, if there is an incident the question will invariably be, "who lifted the ban?".
For the record, I believe that volcanic ash is fairly abrasive (more so than most sand types) and certainly every morning I've seen a light coating on cars. I also understand that significant concentrations were observed at 2,000ft over the midlands a few days ago. But the 2 big concerns are:
1. Ash will melt at lower temperatures than those found in a typical gas turbine, whereas sand generally won't.
2. Ash may react with metals in engine components causing them to become brittle - creating a rather unpleasant latent issue.
Hey Luke, out of interest, are you getting any PSR returns on the ash?
For BAW009, it's widely reported that there was nothing on their weather radar, and I think it was dark at the time, therefore without any knowledge of the ash cloud being there, how could they avoid it?
I'm sure that reporting and monitoring measures have improved immensley since 1982, and that's probably why we're in the situation now.
I'm no expert on the effects of volcanic ash on engines, but I'd still maintain that if there is a risk of the ash being present in significant volumes, then flights shouldn't be permitted in those areas. If it were allowed, it'd only take one aircraft to suffer a problem, and the skies would shut down again. Why take that risk?
The weather is the thing that needs to change - it's not the first volcanic eruption in Iceland in the last couple of decades - but happily, we've not had the Jetstream/weather pattern that has pushed the ash to us and continental Europe before. (Well, in my memory anyway.)
How long before it's safe to fly? I've already said I reckon there will be significant restrictions on flights until the end of this week. Beyond that, who knows? Depends on the weather, or the volcano ceasing. I imagine there will be periods where aircraft can be launched.
As for seeing the ash - I'm not so sure. It's fine particles, high up, and spread over a huge area. I imagine unless there is a definite edge to it, you wouldn't really detect it. You only have to look around at the images of sunsets around the UK over the last week (comparing to other sunset images) to see that something's there - dust scatters blue light more than red. Basically, more dust in the sky means redder sunsets. And, there is evidence of ash reaching the ground in parts of the UK (Daily Mail Report). The question, I suppose, is how much ash does it take?
The impact on aviation businesses is difficult to imagine. My day job involves the support of retail systems, and one of our customers is a large airside retailer - I know they've been hugely impacted by the lack of passengers in airports. NATS too, will be getting any revenue with every day that passes. It's not just the airlines losing out! _________________ J.
Last edited by James T Lowe on Sun Apr 18, 2010 12:13 pm; edited 2 times in total
Hi James obviously were not open at Coventry anymore but no to answer your question, there is nothing showing on primary radar. Perhaps thats because its too far away to see any large concentration.
The radar is pretty effective at filtering out anything that isn't an aircraft, generally anything that is not moving at a reasonable speed is automatically cut out, thats how you get rid of the weather clutter. If we turned that off you still would struggle to detect ash because you get every cloud showing up, absolutly anything including ground objects so distinguishing between ash and normal cloud and general clutter would be near impossible. They do it on weather radar by adjusting the cone so you won't see low level stuff plus some clever filters.
If the ash was thick enough, just as when the weather is appauling and full of CB's they disrupt the radar and even the filters won't get rid of it and the picture will be mildly cluttered. If you knew it was a gin clear day and you were still getting that clutter then i guess you could attribute it to ash.
Also, remember this is (IMO) an insurance issue, as well as a safety issue. Of course there are proven risks when flying through an Ash cloud, and those risks are much greater the closer to the source you are.
But the general closure of airspace and reluctance to fly by the airlines is more to do with the insurance, or lack of insurance. Most of the aircraft won't be insured for damage caused by this sort of nastiness, so they're grounded until the risk has passed.
These are the same insurance companies that require us to have some 2500 hours before we go near some fairly routine rotary jobs.
It's just a shame the insurance companies can 'protect' their revenue to a much greater extent that any other industry, even to the detriment of their customers.
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