@ZOOKER
Surely "the challenge" is to avoid the demise of aircrew, passengers and persons on the ground?
... and equipment?.
IIRC some cancelations in 2010 were made by the airlines and with equipment damage or excessive wear in mind.
Someone in the business here may help refresh my memory.
To the extend that flights may endure increased maintenance costs in the short or long term as a result of volcano ash, who can blame a business from considering that in its overall decision makings.