It is interesting to me that people think the failure was in not detecting the underwear explosives. The failure was in letting this person on the airplane. They had all the information they needed to flag this person and prohibit him from boarding the flight and failed to act.

The TSA insists on gathering all this personal information about every traveler, keeping lists of people and still can’t act when someone is identified. TSA can implement all the regulations they want. Terrorist attacks are stopped by human actions, not machines and regulations.