Investigation performed by the National Transportation Safety Board concluded that the accident was caused by a failure in the fuselage skin due to metal fatigue.

The flight crew declared an emergency and landed the aircraft safely at Yeager Airport in Kanawha County, West Virginia, near Charleston.

[1] Highly magnified inspections found that a long metal fatigue crack had developed at the boundary of two different manufacturing processes used by Boeing in creating the fuselage crown skin assembly.

[1] Boeing finite element modeling had suggested that stress forces in this boundary region are higher due to differences in stiffness, indicating that a failure was more likely to occur in this area after a certain number of pressurization-depressurization cycles.

Following this accident, on September 3, 2009, Boeing issued a Service Bulletin calling for repetitive external inspections to detect any cracks in this more-vulnerable area of the fuselage skin.