Almost certainly not. The legislation says: "An operating air carrier shall not be obliged to pay compensation [...], if it can prove that the cancellation is caused by extraordinary circumstances which could not have been avoided even if all reasonable measures had been taken."
That gets them off the hook for even second order effects. No harm throwing in a claim though, there's no penalty for having a claim turned down.
Fair point.
NATS had failed once, so it failing again doesn't seem extraordinary to me.