Normalization of Deviance: Why Accidents Are Not Always Accidental

On January 28, 1986, the world witnessed an accident that was, at the time, the worst disaster in the history of space flight. With seven astronauts on board, the space shuttle Challenger exploded just 73 seconds after its launch. The investigation into the Challenger disaster revealed cultural and systemic flaws in NASA operations; as a result, the concept of “normalization of deviance” was developed. Normalization of deviance is when unacceptable practices become acceptable behaviors. While the results of this process are often painfully clear, detecting and identifying this phenomenon can be extremely difficult. The Challenger accident, the loss of the space shuttle Columbia in 2003, and other disasters have been shocking reminders of how seemingly innocuous details play essential roles in the interactions of complex systems and organizations. This paper is not about NASA and space shuttles. Normalizing deviance in any safety-critical process or task can be disastrous; allowing deviations in operating, inspection, and maintenance procedures can seriously erode safety margins. Deviation occurs because of physical or psychological barriers to using the correct process; other drivers, such as time, cost, and peer pressure, also contribute. These are not problems that reside solely with the people performing the work. Looking at organizational safety through the lens of human performance recognizes that safety challenges are present at all levels of an organization, as do the opportunities to uncover and address them. This paper takes a human factors approach to organizational safety and outlines some critical features of process drift and normalization of deviance. It also reviews the reality that many accidents have causative factors in production areas and management offices. Finally, it evaluates recent accidents and how they display characteristics of organizational failure and proposes recommendations for improvement.

I. Introduction

On January 28, 1986, the world witnessed an accident that was, at the time, the worst disaster in the history of space flight. The space shuttle Challenger exploded just 73 seconds after its launch, killing all seven astronauts aboard. The investigation revealed multiple factors contributing to the accident, including NASA's organizational culture and critical flaws in making flight safety decisions. The Rogers Commission, tasked by President Ronald Reagan with investigating the disaster, found that NASA had a history of violating its safety protocols. Due to difficulties meeting the requirements, engineering standards regarding the solid rocket booster (SRB) O-ring seals were waived. Evidence that the O-rings could harden and fail at low temperatures, as were experienced overnight and into the morning of the launch, was not thoroughly investigated and ultimately disregarded.