Normalization of deviance

A term coined by sociologist Diane Vaughan describing how an organization can repeatedly accept a known deviation from a safety standard, because nothing bad happened the previous times, until the deviation becomes the accepted norm rather than a flagged risk. Documented in Vaughan's study of the Space Shuttle Challenger disaster (Vaughan, 1996) and referenced in this topic as a recurring organizational pattern behind safeguard gaps. The same pattern shows up far below the scale of a spacecraft: a team that repeatedly ships with a known test failure waived "just this once," or a workflow that tolerates a data quality shortcut because nothing has broken yet, is normalizing deviance on a smaller, more survivable scale, which is exactly why Section 3I's Habit 3 asks you to practice source-checking on small, low-stakes failures rather than waiting for a dramatic one.

A term from sociologist Diane Vaughan, used in the Columbia Accident Investigation Board's 2003 report, describing how an organization gradually accepts a known deviation from expected performance, such as recurring foam strikes or recurring data discrepancies, until it stops treating the pattern as a warning sign.

A term coined by sociologist Diane Vaughan (1996) describing how an organization can gradually come to accept a known deviation from a safety standard or specification as routine, because earlier instances of the deviation did not produce a visible failure, until the deviation is no longer treated as a risk requiring action.

A pattern, documented in the sociologist Diane Vaughan's analysis of the Space Shuttle Challenger disaster and echoed in the Columbia Accident Investigation Board's 2003 findings, in which a known anomaly that has not yet caused catastrophic failure is gradually reclassified from unexpected and concerning to expected and acceptable, often under schedule or budget pressure, until it is no longer treated as a safety-relevant signal.

A pattern, documented by sociologist Diane Vaughan in her study of the Challenger decision, in which a known deviation from a specification is accepted once, then repeatedly re-accepted by citing its own prior approval rather than new evidence, until the deviation becomes routine and its underlying risk is no longer treated as an open problem requiring resolution.