Voy Por Ustedes

This no-flying business has nothing to do with planes falling out of the sky. These things can fly through this cloud no worries. The very fact that they've had planes flying round it so people can photograph it proves that.

It's simply down to the fact that the insurance policies Boeing and Airbus issue with their planes become null and void if they are downed while after flying through or near volcano ash. So even if the NATS said oh go on then, you can fly just fly lower, the airlines would still have to sheepishly remain grounded.