(CNN) -- It's called the Terrorist Identities Datamart Environment, and weeks before authorities say he got on a plane with a bomb, Umar Farouk AbdulMutallab was in it. 

The vast government databank, known as TIDE, is administered by the FBI's Terrorist Screening Center. It contains information about hundreds of thousands of people, the majority of them foreign nationals, who are suspected of having terrorist leanings. 

An FBI official said AbdulMutallab was included in TIDE after his father warned the U.S. Embassy in Nigeria of his son's hard-line beliefs and possible ties to militant Islamists. 

To understand how he could have been under the government's scrutiny and still make it onto a U.S.-bound plane with an explosive, you have to understand the way the government's watch list system works. TIDE is just the start. 

The FBI uses the raw information contained in the TIDE databank to determine whether to put the subject onto the government's terror watch list, known as the Terrorism Screening Data Base. That list contains the names and aliases of about 400,000 people, but AbdulMutallab didn't make the cut. 

According to Chad Kolton, a spokesman for the FBI's Terror Screening Center, there wasn't enough hard evidence to back up AbdulMutallab's father's fears, and so he wasn't placed on the terror list. 

The bureau's own Web site spells out the criteria for inclusion in the screening database, saying that "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 are included." 
was there hard evidence against him?
what does TIDE stand for?
is TIDE just the start?
who uses the information in TIDE?
who uses the information in TIDE?
Which FBI department administers it?
Did the suspect get onto a plane?
where was it going?
who did the father warn?
where?
how many people does TIDE have information on?
what is the government watchlist known as?
did he end up on the list?
what kind of info does FBI use to determine who gets on the list?
who is the FBI spokesman mentioned?
what did he get on the plane with?
what is his full name?
what did his father suspect he had ties with?
what did he say about his beliefs?
does the list also contain aliases?
not enough
 there wasn't enough hard evidence 
Terrorist Identities Datamart Environment,
Terrorist Identities Datamart Environment,
yes
TIDE is just the start. 
FBI
The FBI uses the raw information contained in the TIDE databank
FBI
FBI uses the raw information contained in the TIDE
Terror Screening Center,
FBI's Terror Screening Center,
yes
he got on a plane 
unknown
unknown
the U.S. Embassy
father warned the U.S. Embassy
Nigeria
 U.S. Embassy in Nigeria
400,000
That list contains the names and aliases of about 400,000 people
Terrorism Screening Data Bas
error watch list, known as the Terrorism Screening Data Bas
no
but AbdulMutallab didn't make the cut. 
suspected to be or have been engaged in conduct constituting
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 are included." 
Chad Kolton
Chad Kolton, a spokesman for the FBI's Terror Screening Cente
a bomb
got on a plane with a bomb
Umar Farouk AbdulMutallab
 Umar Farouk AbdulMutallab 
militant Islamists
son's hard-line beliefs and possible ties to militant Islamists
hard-line
on's hard-line beliefs and possible ties to militant Islamists. 
yes
 That list contains the names and aliases o