Via the Economist, Bruce Schneier points out what should be obvious:
In the entire decade or so of airport security since the attacks on September 11th 2001, the TSA has not foiled a single terrorist plot or caught a single terrorist. Its own “Top 10 Good Catches of 2011” does not have a single terrorist on the list. The “good catches” are forbidden items carried by mostly forgetful, and entirely innocent, people—the sorts of guns and knives that would have been just as easily caught by pre-9/11 screening procedures. Not that the TSA is expert at that; it regularly misses guns and bombs in tests and real life. Even its top “good catch”—a passenger with C4 explosives—was caught on his return flight; TSA agents missed it the first time through.
In previous years, the TSA has congratulated itself for confiscating home-made electronics, alerting the police to people with outstanding misdemeanour warrants and arresting people for wearing fake military uniforms. These are hardly the sorts of things we spend $8 billion annually for the TSA to keep us safe from.
Don’t be fooled by claims that the plots it foils are secret. Stopping a terrorist attack is a political triumph. Witness the litany of half-baked and farcical plots that were paraded in front of the public to justify the Bush administration’s anti-terrorism measures. If the TSA ever caught anything even remotely resembling a terrorist, it would be holding press conferences and petitioning Congress for a bigger budget.