There, this information is edited and combined with other agencies' information to provide the refined data for TSDB (Terrorist Screening Database). In theory, this provides, according to the FBI, "'one-stop shopping' so that every government screener is using the same terrorist watchlist-whether it is an airport screener, an embassy official issuing visas overseas, or a state or local law enforcement officer on the street."
Actually, it doesn't work that way. The cop on the street corner doesn't have access to the TSDB, nor do the scanners in the airport. Instead, each government agency concerned with terrorism then makes its own call on how to handle the information. So, for example, someone who's on the TSA's (Transportation Security Administration) "no-fly" list of about 4,000 people may not be on the State Department's CLASS (Consular Lookout and Support System PDF Link) and so on.
In addition, while at the moment, most of the concern is about how Abdulmutallab slipped through the system, it wasn't long ago that most of the concern over TIDE and the TSDB was about false positives. For example, former Senator Ted Stevens' wife was frequently delayed in her flights at one time because airlines and TSA staffers confused her, Catherine Stevens, with the then 'no fly' watch-listed, musican Cat Stevens.
So, yes, the database systems failed, but it wasn't a failure of the technology. It was a failure of insufficient data and any system that tries to use fragmentary and incomplete data to tell the difference between a crank and a terrorist.
For all that Republicans are proclaiming that this episode shows how bad our security is now and that President Obama has ordered a review of the nation's terror watch-list system, neither complaints nor reform can render our terrorist defenses invulnerable.
As Christopher Hitchens points out in Slate, "We had better get used to being the civilians who are under a relentless and planned assault from the pledged supporters of a wicked theocratic ideology. These people will kill themselves to attack hotels, weddings, buses, subways, cinemas, and trains. They consider Jews, Christians, Hindus, women, homosexuals, and dissident Muslims (to give only the main instances) to be divinely mandated slaughter victims. Our civil aviation is only the most psychologically frightening symbol of a plethora of potential targets." And, no technology, not how we use it, will provide perfect protection against them.