What Are the Key Airline Security and Terrorists Databases?

With the recent arrest of a suspect in the failed bombing of Northwest flight 253, one of the questions asked was why was this person allowed to get on an airplane if his name was in one of the US databases of suspected terrorists? The short story is that the suspect would have been barred from boarding if he were on a very specific list called the Transportation Security Administration's (TSA's) No-fly list. He would have been subject to extra scrutiny, but not necessarily barred from boarding, if he were on the TSA's Selectee list.

The suspect was on a much larger list of people with terrorists ties, but being on that list doesn't lead to increased TSA scrutiny. What follows is a very brief description of these three databases, plus a fourth database, that are relevant to the recent bombing situation.

Terrorist Identities Datamart Environment (TIDE)
This is the US government's central repository of information on international terrorist activities. The database includes people who commit terrorist activities, who plan such activities, or perform supporting activities such as fund raising providing safe houses. The suspect, Umar Farouk Abdulmutallab, was added to this database last month, and there are about 500,000 unique individuals in the database, of which 95% are non-US citizens. For more details, you can view the fact sheet on this database.

Terrorist Screening Database (TSDB)
only individuals who are known or reasonably suspected to be or have been engaged in conduct constituting, in preparation for, in aid of, or related to terrorism. This database consolidates information that used to be located in several different US government agencies. It is more restrictive than the TIDE database, and contains about 400,000 names. The suspect in the bombing was not one of them. The FBI has a list of frequently asked questions about this database.

Selectee List
Maintained by the Transportation Security Administration (TSA), this database contains the names of individuals who must undergo additional security screening before being permitted to board an aircraft. This list, which has about 14,000 people, is a subset of the TSDB.

No-fly List
As the name implies, this is a list of people who are not allowed to board an airliner. Like the Selectee List, this No-fly list is maintained by the TSA and is a subset of the TSDB. This list has fewer than 4,000 names.

So far, the US government has admitted that there was insufficient information available on the suspect to place him in any of the last three lists, including the no-fly list. Also, the suspect's US entry visa, which was granted in 2008 before he was placed on the TIDE list, was not restricted or revoked after being placed on that list.