The Twentieth Hijacker
Unlike the other hijackers, Moussaoui seems to have been a thoroughly incompetent pilot, having failed to solo a C172 after nearly 60 hours of training. After 9/11, there was a tremendous amount of attention on arab flight students...I often wondered about some of the students at the school where I'd taught the previous summer. I know the FBI was at the school several times and took records.
Moussaoui was apprehended due to a sharp ex-airline pilot working as an instructor for Pan-Am Int'l Flight Academy, Clancy Prevost. You can read an interesting article about it here. It is interesting to note that Prevost's suspicions were flared by both Moussaoui's incompetence and his ethnicity/apparent religion. Fast-forward to today, after thousands of lives lost to terrorism and four years of struggle against islamic fundamentalists, and political correctness still keeps airport security officials from profiling young arabic males for additional screening.
No, I'm not being reactionary and far-right about this. I'm not saying this out of hate for arabics or muslims. I'm not racist except in the sense that I recognize that a young arabic male is statistically much more likely to engage in terrorist acts than your 80-year old grandmother. Yet, behold, our airport security apparatus: still entirely incompetent in identifying and stopping weapons passing through checkpoints, only able to closely search a select few; and officialdom denies us the one weapon that might give us an upper hand: our knowledge of the enemy.
Folks, we're safer than we were 4 years ago, but it isn't because of the TSA's window dressing. It's because any terrorist will only gain access to an airline cockpit through a horde of angry passengers, determined flight attendants, a reinforced cockpit door that's staying locked, me weilding a crash axe, and increasingly often, the captain and his gun. No American airliner will again be used as a guided missile. Still, the twentieth hijacker is still out there somewhere. And I'd prefer the TSA stop him before he gets on my plane.