I've read the lead up to the day itself. Farmer's book is designed as a chronology (years, months, weeks, days) leading up to 9/11. His stated reason for doing so is to give the reader an understanding of how many steps were missed along the way and how good options were no longer available once the hijackings started. For example, the best case scenario was that NORAD would have shot down planes filled with passengers.
His main source for his theory of what went wrong on 9/11 is Amy Zegart. She is the author of
Spying Blind: The CIA, the FBI, and Origins of 9/11.She gave a presentation about her theory:
Zegart presentation followed by Scott Shane and Mark Lowenthal commentaryFrom Zegart's presentation:
...the human story is largely irrelevant in understanding intelligence adaptation failure. Those who want to learn what went wrong and how to fix it need to understand something far more boring and intriguing than personal failure and that is bureaucracy. The organizational pathologies that lead talented individuals to make poor decisions.
While Farmer and Zegart make good points about bureaucratic problems their analysis doesn't ring true when they pretend that the conduct of specific officials wasn't applicable to the success of the attacks. There are repeated instances where individuals acted in a manner indicative of bad faith. Instances where individuals took advantage of bureaucratic problems in order to impede al Qaeda related investigations. The Farmer/Zegart analysis tracks with the popular media view of holding powerful officials to an extremely low standard of conduct. Tenet's contradictory conduct--dire warnings of possible attacks vs. withholding of information about suspected perpetrators of those possible attacks--couldn't possibly be chalked up to some sort of political corruption. It simply had to be because the CIA was still on Cold War footing.