The aircraft operated on American Airlines Flight 1 from New York to Chicago, Illinois with intermediate stops at Newark, New Jersey; Buffalo, New York; Detroit, Michigan; and South Bend, Indiana. Flight 1 departed from Buffalo at 21:07. When Flight 1 arrived in the vicinity of the point where the accident occurred, the plane commenced to descend, circling to the right and apparently banked normally for the radius and speed of the turns. The diameter of the initial circle was approximately 1-1/2 miles; thereafter during the descent the radius progressively diminished. After completing approximately four circles, the airplane recovered from the spiral in close proximity to the ground, zoomed to an altitude of about 200 to 500 feet and probably stalled. It then dived to the ground, striking in a nose-down attitude at an angle of approximately 70 degrees with the horizontal, and immediately burst into flames. PROBABLE CAUSE: Undetermined