On 15/04/2010 18:44, Neil wrote:
Interesting looking at flightradar24.com - Not a single civil movement
over the UK and a lot of western Europe . . . .

www.flightradar24.com

I don't really understand why this is such a big deal though.

Presumably the ash cloud is not 'that' dense otherwise we would have a
blackout.

Why then is it so important that aircraft avoid what seems to be a
little bit of fine dust?

I understand that the plane can suffer engine failures etc if it goes
through dense cloud of volcanic ash but is that likely to happen at such
limited concentrations?

And will I have to clean the car again once it's all fallen out of the
sky!!??

Looks like France and Spain have shut their airspace too now?

"Neil" wrote in message
...

For those interested, here is the reason why the planes have been grounded
. . .

http://tinyurl.com/y394h58


Good link, and well explained. However, in this case, the situation is
slightly different.

Under normal circumstances, when a volcano blows, the larva and ash are
expelled directly into the air, cool slowly, and the ash ends up somewhat
like pumice, a very soft rock, that although being dangerous to engines, is
fairly benign stuff otherwise.

In this particular instance, the larva and ash is being ejected through a
glacier, partially melted, but the majority still being solid frozen ice.
This causes the larva and ash (detritus) to cool very, very quickly, and in
doing so forms a glass like substance, as has been mentioned on the news.
These particles are also a lot smaller than the softer type.

From Neil's link, the damage caused by this glass is well explained, but
this is after the ash has been through the guts of the engine. In the
current case, the detritus is already glass before it hits the plane, and
this glass is very similar to emery dust, or sand paper, and will strip
engines bare before it is even half way through them, not to mention the
effect it will have on the body of an aircraft, an effect that is not
present with the softer pumice type of ash. Bear this in mind. The aircraft
will hit these particles at several hundred miles an hour, so it is like
putting the aircraft in front of a sand blaster. And I think everyone here
knows the effect that has on any material!

jim, Northampton

On Thu, 15 Apr 2010 20:00:18 +0100
"Anne Burgess" wrote:


People are trying to tell me that gliders are also grounded.
That is total nonsense. For heaven's sake, they don't *have*
engines, and they are unlikely to get up to 55,000 feet. The UK
height record is only 38,000 feet.

Apparently volcanic ash is *very* abrasive and will turn forward facing
glazing opaque quickly. Potential lack of vision through affected
windscreens for landing seems to be a major factor in the grounding of
aircraft. It'll also give the flies on leading edges a hard time; and
take away the gel-coat too, which you might consider a bit more of a
long term problem. Ash is expected down to 5,000ft and to SFC in some
areas.

As usual with aviation matters PPruNe has some experts appearing with
specialist knowledge (and the usual proportion of idiots...).
http://www.pprune.org/rumours-news/412103-ash-clouds-threaten-air-traffic.html



Mike
--
Mike Causer

In article ,
says...
Interesting looking at flightradar24.com - Not a single civil movement
over the UK and a lot of western Europe . . . .

www.flightradar24.com



I'm wondering if perhaps you maybe regret pointing us all in that
direction.

--
Alan LeHun

On Apr 16, 5:35*pm, Alan LeHun wrote:
In article ,
says...

Interesting looking at flightradar24.com - Not a single civil movement
over the UK and a lot of western Europe . . . .

www.flightradar24.com

I'm wondering if perhaps you maybe regret pointing us all in that
direction.

--
Alan LeHun

Some of the smaller prop planes are having a field day over Dawlish
this evening!