The Christmas flight bomber terrorist used the explosive PETN sewn into a sort of 'suicide - underwear bomb'. The 80+ grams of PETN, a military grade explosive, failed to detonate because it was not properly set up. Basically, it was the terrorist's own incompetence (again, think Shoe Bomber) that saved the flight and allowed the passengers time to subdue him. Security needs to be stepped up or fixed as we should not rely on the terrorists stupidity for our safety.
"The plot to blow up an American passenger jet over Detroit was organized and launched by al Qaeda leaders in Yemen who apparently sewed bomb materials into the suspect's underwear before sending him on his mission, federal authorities tell ABC News.
Investigators say the suspect had more than 80 grams of PETN, a compound related to nitro-glycerin used by the military. The so-called shoe bomber, Richard Reid, had only about 50 grams kin his failed attempt in 2001 to blow up a U.S.-bound jet. Yesterday's bomb failed because the detonator may have been too small or was not in "proper contact" with the explosive material, investigators told ABC News."