9-11 should never be known as a day that we failed to imagine could ever happen. The 9-11 Commission was simply wrong to conclude that the attack was unpreventable. For years, the warnings were everywhere. Tragically, those in charge of aviation security who could have done something, failed to do so.

If the terrorists were not able to take the planes over and fly them into the WTC and Pentagon, 9-11 is a very different day and our world a fundamentally different place.

Read a great piece on how 9-11 was the result of an aviation security system set-up to fail.