in my mind the PDB was simply a Simpsonism - "Doh!". On September 10th, I finished one of Tom Clancy's books, written many years prior, that ended with a Japanese airline pilot slamming a fully-fueled 747 into the Capitol Bldg in Washington, D.C. killing the president and many congressmen. Now, knowing the makeup of security types in the goverment, I would assume that Clancy's works fill most of their library shelves. I would also assume that his works are constantly monitored by intelligence agencies because of his vast knowledge of extremely modern weapons systems.

When I read about that incident in the novel it was immediately obvious to me that slamming a plane into a building full of people was a huge and ominous threat and as you can imagine, even though shocked it came to pass that next day, knew immediately what was going on before the news media started putting it together.

This was not some new concept and if the government did not consider it a huge security hole, they were sorely derelict.