The suspect’s name was inserted last month into the Terrorist Identities Datamart Environment, or Tide. About 550,000 individuals are registered in the database. A subset of that is the Terrorist Screening Data Base, or T.S.D.B., which has about 400,000.

By contrast, fewer than 4,000 names from the T.S.D.B. are on the “no-fly” list, and an additional 14,000 on a “selectee” list that calls for mandatory secondary screening, an Obama administration official said. At the time Mr. Abdulmutallab’s name was recorded in the Tide database in November, the official said, “there was insufficient derogatory information available” to warrant putting him in the T.S.D.B., no-fly or selectee lists, and so he was not on any watch list when he boarded the plane bound for Detroit.

President Obama ordered a full review of the law enforcement and intelligence databases related to the no-fly list to make sure the procedures and practices still make sense, a senior administration official said Saturday.

Mr. Abdulmutallab was issued a regular visitor’s visa by the United States Embassy in London in June 2008, the administration official said. There was no “derogatory information available” on him at the time he applied, and he was granted a two-year visa, which is still valid, the official said. He had traveled to the United States once before, to Houston in August 2008.

Image The police searched the basement of a building in London, where it is believed that Umar Farouk Abdulmutallab had been a student. Credit... Akira Suemori/Associated Press

Representative Bennie G. Thompson, a Mississippi Democrat who leads the House Homeland Security Committee, said in a telephone interview that he would hold hearings next month when Congress returns from its recess to determine whether airport screening processes were at fault, scanning equipment was inadequate, information was not shared among federal agencies, or human error was to blame.

Mr. Abdulmutallab told F.B.I. agents he was connected to the Qaeda affiliate, which operates largely in Yemen and Saudi Arabia, by a radical Yemeni cleric whom he contacted online. The cleric is not believed to be Anwar al-Awlaki, an American-born imam who has spoken in favor of anti-American violence and who corresponded with Maj. Nidal Hasan, the Army psychiatrist charged in the killings of 13 people in a shooting spree last month at Fort Hood, Tex.