I would ask just one who claims it is safe, "What is the volcanic cloud density that is 'safe' and when is it not safe to fly, and, should an encounter occur, what is the safest course of action?" Though the QRH tells us what to do, such a response is based upon the fact that one is already in trouble. I think stating that the shut-down was 'out of proportion to the risk' is foolish and cannot be defended on belief alone.
I wasn't making the statement on belief. The FACTs as best as they are currently assembled say.
- No aircraft has ever encountered a loss of power that could not be recovered at lower altitude - even while flying through significant densities of ash.
- There appears not to be a single documented instance of an in flight abnormality attributable to ash with a density lower than that of visible haze - and most seem to have been in thin cloud or denser. (This is different from saying low levels of ash don't result in accelerated wear - which it quite likely does)
- Operator's in areas of volcanic activity have SOPs that allow them to continue to operate - with limitation (which curiously didn't seem to apply to Europe when the skies where opened.)
- There are risks that down aircraft every year and operators continue to operate exposed to these risks (because you couldn't operate a business if you didn't - and after all the only reason the airline industry exists is to make money serving its customers).