As we approach the 5th anniversary of the 9/11 attacks on the US and many of us are asking the question about whether we are safer today when we fly and if so, why?
I am sure that we are much safer today than we were on 9/10, but it isn't because of all the heightened security, the ban on metal knives, box cutters, or even liquids on planes, the increased presence of air marshals, or the no-fly lists.
I believe the primarily reason we are safer is because the flight crew now knows that if they give up control of the plane, they provide the enemy with a weapon of mass destruction.
Pilots (who were trained to cooperate with hijackers prior to 9/11) will do everything in their power to get the plane to the ground at an airport rather than give up control (including using the plane itself as a weapon to disarm the hijackers -- by doing interesting aerobatic operations) because they know that giving up control will likely result in the death of everyone on board and probably many on the ground.
The one security measure put into effect that lends great support to the pilot is the reinforced cockpit door. That, of all the things done by TSA/FAA, is probably the most significant improvement in all our safety.