Virgin and Glueball have missed the point. Up until September 11th. the statistical issue was primarily as they state it: "What are the odds against any particular flight having a problem?".
But now the statistical issue is entirely different. The question has become 'What are the odds against ANY random flight being turned into a guided missile aimed at the public at large?"
Now in rational terms that may not be a lot of difference, but perception has nothing to do with statistics. The political reality is that the airline industry has to now assess the risk that it collectively poses to the wider public if its security is lax (or ORD or YVR).
It is no good ranting about that. That's the way it is. It is politically inescapable as long as the image of those ruins is imprinted on the minds of the world: i.e. for a very long time.