To help get air traffic going again I suggest we revive the practice of deifying a human being by dropping them in the crater. Our hero would need to be the right shape to act as an effective plug, and willing to undergo the indignity of wearing a loud shirt to aid in effective remote placement. And they would have to be a veritable rotweiler of a character, who wouldn't let no stinkin' 4 million tons of ash get past them. Alas, off the top of my head, I can't think of any obvious candidate.....