There should be ample material on the subject. For the most part, the significant changes were modest followed by some very expensive window dressing. As example, the change in policy and procedures from going along with someone taking command of an aircraft by force to resistance coupled with the cockpit door changes were of little cost but tremendous effect. A good deal of the Homeland Security stuff that has served to make commerical flying almost insufferable does little in terms of productive security in my opinion. We have long been a country that passes a law about everything but as the people we are dealing with totally ignore law, what purpose does it accomplish. I don't know if things like "no-fly" lists or 12-5 programs really do much. There are few places in the business that with patience and knowledge you could not breech.
