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http://timesonline.typepad.com/science/2010/04/aeroplanes-beware-when-volcanic-ash-attacks.html
04/15/2010
Aeroplanes beware when volcanic ash attacks
Airports across Northern Europe are facing a day - possibly days - of chaos as a huge plume of ash blows southwards from the erupting Eyjafjoll volcano in Iceland.
The volcanic ash is made up of tiny rock particles created when bubbles break due to gasses in volcanic eruptions. The ash looks like a grey talcum powder, but is slightly more abrasive. If ejected high enough into the atmosphere it can be dispersed around the globe by high winds. The cloud of ash is currently sitting at around 55000ft - exactly the cruising altitude of aeroplanes.
The main mass is over Scandinavia, but it is also over the north of Great Britain and is likely to spread south over the whole island by the end of the day.
The cloud is not particularly dense - it is unlikely to be noticed by people on the ground. However, for engines travelling at the right altitude at high speed such a cloud could spell disaster.
The particles can accumulate inside jet engines - in particular inside tiny orifices through which cool air is blown to control temperatures inside the engine. Once these small pepper-pot type holes are clogged the engine begins to overheat and within minutes will shut down, leaving the plane plummeting Earthwards.
In 1982 British Airways and Singapore Airways jumbo jets lost all their engines when they flew into an ash cloud over Indonesia, and a KLM flight had a similar experience in 1989 over Alaska. On each occasion, the plane fell to within a few thousand feet of the ground before it was possible to restart the engines.
Stewart John, a former Cathay Pacific engineer, said that the current measures are nothing short of essential. "It's a very serious threat, you can't underestimate it. You can't say that people are overreacting," he said.
How long the ash cloud will hang around is entirely dependent on wind strength and direction in the high atmosphere. More ash is pouring forth from the volcano, meaning that the cloud above the UK could persist far beyond this evening.
Met Office forecasts of the ash cloud at 06:00, 12:00, 18:00 and 24:00 (midnight) today have been issued by the UK Volcanic Ash Advisory Centre, which is part of the Met Office.
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04/15/2010
Aeroplanes beware when volcanic ash attacks
Airports across Northern Europe are facing a day - possibly days - of chaos as a huge plume of ash blows southwards from the erupting Eyjafjoll volcano in Iceland.
The volcanic ash is made up of tiny rock particles created when bubbles break due to gasses in volcanic eruptions. The ash looks like a grey talcum powder, but is slightly more abrasive. If ejected high enough into the atmosphere it can be dispersed around the globe by high winds. The cloud of ash is currently sitting at around 55000ft - exactly the cruising altitude of aeroplanes.
The main mass is over Scandinavia, but it is also over the north of Great Britain and is likely to spread south over the whole island by the end of the day.
The cloud is not particularly dense - it is unlikely to be noticed by people on the ground. However, for engines travelling at the right altitude at high speed such a cloud could spell disaster.
The particles can accumulate inside jet engines - in particular inside tiny orifices through which cool air is blown to control temperatures inside the engine. Once these small pepper-pot type holes are clogged the engine begins to overheat and within minutes will shut down, leaving the plane plummeting Earthwards.
In 1982 British Airways and Singapore Airways jumbo jets lost all their engines when they flew into an ash cloud over Indonesia, and a KLM flight had a similar experience in 1989 over Alaska. On each occasion, the plane fell to within a few thousand feet of the ground before it was possible to restart the engines.
Stewart John, a former Cathay Pacific engineer, said that the current measures are nothing short of essential. "It's a very serious threat, you can't underestimate it. You can't say that people are overreacting," he said.
How long the ash cloud will hang around is entirely dependent on wind strength and direction in the high atmosphere. More ash is pouring forth from the volcano, meaning that the cloud above the UK could persist far beyond this evening.
Met Office forecasts of the ash cloud at 06:00, 12:00, 18:00 and 24:00 (midnight) today have been issued by the UK Volcanic Ash Advisory Centre, which is part of the Met Office.
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Posted by Hannah Devlin on April 15, 2010 in Engineering | Permalink <!-- twit this button begins--><!-- Begin TwitThis (http://twitthis.com/) --><SCRIPT type=text/javascript src="http://s3.chuug.com/chuug.twitthis.scripts/twitthis.js"></SCRIPT><SCRIPT type=text/javascript><!--document.write(' | Post to Twitter');//--></SCRIPT>| Post to Twitter <!-- /End --><!-- twit this button ends--><!-- AddThis Button BEGIN --><SCRIPT type=text/javascript>var addthis_pub="articletol";</SCRIPT>
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