For obvious reasons, security, especially airplane security, is back in everyone’s thoughts and we had a lively discussion here recently about what methods would work.
While editing the wikipedia article about El Al, I found this fascinating article in Atlantic Monthly (pdf) on the web, which, while from 2002, is extremely current. The subject of the article, Bruce Schneier, a computer crypto geek and security consultant, explains why most of the approaches to increased secuity since 9/11 fail badly – that is, once they fail, they fail catastrophically. One example: all the additional biometric identification proposed now for our ID cards would not have prevented Mohammed Atta from flying his plane into the twin towers; he and his compatriots used their real identities. Similar things hold true for the tech-intensive attempts to keep bombs and weapons out of the plane. Once the attacker is beyond the barrier with them, the system fails badly.
A system that fails well, he holds, is instead one that does not depend on the attacker being unaware of it. He cites the awareness that, nowadays, passengers would risk their own life to tackle a hijacker. Knowing about this fact does not help the attacker, but knowing that old-style scanner cannot detect liquid explosives almost did. Armored cockpit doors meanwhile are a classic example of compartmentalization—they contain the failure after it has occured. And as the article nicely points out, methods like containment do not cause the widespread damage to civil liberties the way the data gathering approach does.
The third element he notes is the human one, where we come back to how I found the article. El Al does not (only) protect its planes by bomb sniffers and background checks. They talk to you before you board their planes.