 The initial 1978 bombing was followed by bombs sent to airline officials , and in 1979 , a bomb was placed in the cargo hold of American Airlines Flight 444 , a Boeing 727 flying from Chicago to Washington , D.C. The bomb began smoking , forcing the pilot to make an emergency landing . Some passengers were treated for smoke inhalation . Only a faulty timing mechanism prevented the bomb from exploding . Authorities said it had enough power to " obliterate the plane " . 
