Prof Singer makes a good point, but then people don't tend to be logical about these things. Look at the number of (stereotypically) Daily Mail readers who demand that even one child harmed, ever, through the negligence of a social worker should result in mass sackings and the resignation of the government - but who simultaneously object violently to restrictions on smoking in public buildings and workplaces.

That said, I think air travel is a bit of a special case. People don't become terrified of travelling by road if there's a coach crash in fog on the M1, but a single plane crash that might, perhaps, possibly be linked with this ash cloud would be devastating in terms of public reaction. If the public accepted a plane crash or two every year, then this wouldn't be the case - but they expect aviation to have higher standards than anything else.