You got a point... I would add "LOOK" into the screening too. Tada, you just screen out 90% of the terrorists. Richard Reid failed to detonate because he looked extremely suspicious and got kicked out from the previous flight. The 24 hour delay is the reason why the shoe did not detonate. Profiling saved lifes in this case.
http://media.thestar.topscms.com/ima...5110a3251.jpeg

