DETROIT -- Terror suspect Umar Farouk Abdulmutallab pleaded not guilty Friday in a federal court in Detroit on a six-count indictment for allegedly attempting to blow up a Detroit-bound plane and murder its 279 passengers and 11 crew members.

Mr. Abdulmutallab entered the courtroom just before 2 p.m. Friday shackled by his feet and wearing a white T-shirt, khaki pants and blued shoes.

He...