I sympathize with the tone of posts like the ones I have excerpted below.
Post 255
I don't know that much about volcanoes, but there is very little information available to Joe Public which indicates that the ash cloud would be a danger. Yes, there's a plume around the Shetlands, but Joe Public living in London who wants to fly from Gatwick to Spain can't see how that affects him.
Presumably some people reading this thread have access to rather more information than is publicly available. If so, could they consider making it available to Joe Public, or do a better job than just saying 'When Eric Moody....'
London is 1,000 miles away from the volcano - so any ash dispersal is likely to be at a relatively steady pace dependent on the wind and presumably moderately predictable based on meteorological forecast, rather than relatively unobservable underground geological events causing the volcano to suddenly increase its activity
I can't see any national security reason as to why information on the extent of the ash or volcanic gas should not be public. Show people the scientific evidence and they'll stop saying it's an over-reaction
Post 258
As one of those who has to sit in the ash cloud...or not! I'd greatly appreciate more info/debate on the risk assessment process which has led to this decision. The situation has repeatedly been described as "unprecedented". It isn't. There are active volcanoes all over the place and we work round them. What is so much worse about this one?
I do agree that it is necessary to both understand, explain and react to real or perceived aviation threats that affect us all.
It is the job of the aviation safety professionals to perform this task susch that those among us who are the better communicators can at least advise us.
The idea behind the warnings about aviation and volcanic ash were based on accumulated experience over 30 years and multiple near accidents. The general nature of the warnings were thought to be necessary on a time and knowledge based concept.
If-you-don't Know-then-don't Go
This was based on the belief that in a relatively short time period we would know enough about the make up of the ash, its altitudes and expected progression. I'm afraid that I may have had some unrealistic expectations that this knowlege would be within 24 hours of a hazardous eruption. On the other hand there could be a counter argument that the aviation community does know enough to restrict operations in certain locations for the period of time it does take for the cloud to disperse.
I'm not a vulcanologist and defer to the obvious expertise that has already demonstrated itself in this thread
There are two sides to the expected threats; rapid system deterioration significantly affecting the safe operation of a flight (including engines, airframe and avionics) and long term issues requiring significant maintainence actions. Risk assessment experts can always extrapolate the past history to determine relative risk for either of these effects. And of course apply a cost benefit regarding the maintainence vs operation costs. However, I'm sure that most of your would not support a cost benefit analysis of losing a transport aircraft.
So the question is how much is too much regarding volcanic ash?.
The experts need to know the particulate size. Smaller, (the stuff that stays at high altitudes) is worse since it's dependent on residence time withi the combustor flame. The experts also need to know the relative makeup of melting points of the particulate mater. If this can be identified and modeled within a fortnight then we might be able to make some progress to temper our reaction to the threat.
If the models are not calibrated than the shoot-from-the-hip approach might be to take an aircraft into the cloud with engines and systems running at various conditions (not all have to be at full up) and examine the results afterwards.
OK some of you wanted to debate this so I threw out the first grenade
