Officials now say tragedy was only averted on Northwest flight 253 because a makeshift detonator failed to work properly.

Bomb experts say there was more than enough explosive to bring down the Northwest jet, which had nearly 300 people aboard, had the detonator not failed, and the nation's outdated airport screening machines may need to be upgraded.
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According to investigators, the bomb used yesterday was built in Yemen by a top al Qaeda bomb maker.
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[Umar Farouk Abdul] Abdulmutallab was on a terrorism watch list, but not on a no-fly list. Said Clarke, "So once again, we have the U.S. government, as in the case of the Fort Hood attacks, knowing about someone, knowing that they were suspicious, but that information didn't get to the right people in time."