This really was a close call and even though I can't stand the thought of any more seemingly pointless anti-terror flying rules, I suppose it's inevitable:

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to bring down the Northwest jet, which had nearly 300 people aboard, had the detonator not failed, and the nation's outdated airport screening machines may need to be upgraded.

"We've known for a long time that this is possible," said Richard Clarke, former counterterrorism czar and ABC News consultant, "and that we really have to replace our scanning devices with more modern systems."

Clarke said full body scans were needed, "but they're expensive and they're intrusive. They invade people's privacy."

Al Qaeda, said Clarke, is aware of this vulnerability in the U.S. airport security system. "They know that this is a weakness and an Achilles' heel in our airport security system and this is the second time they've tried it."