Walters had always wanted to fly, but bad eyesight prevented him from becoming a pilot.

NPR: Pinback: The Rise and Fall of 'Lawn Chair Larry'

In this case, the government had information about Umar Farouk Abdulmutallab, but no one added him to either the no-fly list, which would have prevented him from boarding a U.S.-bound plane, or the selectee list, which would have triggered secondary screening that might have caught the explosives hidden under his clothes.

WSJ: The Middle Seat | How to Improve Travel in 2010