Document Type


Publication Date





On January 31, 2000, Alaska Airlines flight 261, an MD-83, crashed into the Pacific Ocean; after airplane pitch control was lost as a result of the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads (NTSB, 2003). Accident investigation revealed a wide range of human, technical, and organizational factors contributing to this tragic event, providing a case where popular linear models and methods have difficulty addressing the full complexity of the processes leading up to the accident. This paper treats each of the steps of analysis according to the Functional Resonance Accident Model (FRAM; Hollnagel, 2004), a systemic non-linear modeling method, and discusses how functional resonance occurred through the variability in functions performed by joint human, technical, and organizational systems. It thereby aims to facilitate a better understanding of how functional variability in design, certification, limited and inadequate maintenance, negligent safety culture, economic factors, and human performance together can resonate and contribute to accidents. In this way it aims to contribute to accident prevention and the engineering of more resilient complex dynamic systems.