After looking at this FBI Cybersquad image last week, I'm not surprised to hear that crappy government software that can't account for misspellings was the main reason why the underwear bomber was able to get on a Northwest Airlines flight.
Mr. Abdulmutallab possessed a U.S. visa, but this fact was not correlated with the concerns of Mr. Abdulmutallab's father about Mr. Abdulmutallab's potential radicalization. A misspelling of Mr. Abdulmutallab's name initially resulted in the State Department believing he did not have a valid U.S. visa. A determination to revoke his visa however would have only occurred if there had been a successful integration of intelligence by the CT [counterterrorism]community, resulting in his being watchlisted.
In other words, when "Abdulmutallab" was typed into a government computer with a misspelling, the software was unable to compensate - a flaw that has been all but eliminated in on most major search platforms (like Google for instance). Unfortunately, this problem could have been overcome had the NCTC and CIA run a check on all available databases. It was only after the flight took off that the passenger manifest was crosschecked against known terrorists. Alarming... you bet it is. [Danger Room via Silicon Alley Insider]