Contributing factor

A condition or decision the investigation's evidence shows also mattered to the outcome, listed separately from the probable cause rather than folded into it. HAR-19/03 lists several: the developer's inadequate safety risk assessment procedures, its ineffective oversight of vehicle operators, its lack of mechanisms for automation complacency, the pedestrian's crossing outside a marked crosswalk, and the state transportation department's insufficient oversight of automated vehicle testing. Naming a factor as contributing rather than probable-cause is a precision, not a demotion: both are stated as real, evidenced parts of the explanation.

Any condition, system failure, process gap, or decision that helped make an incident possible or worse, distinct from the single triggering action. A defensible post-incident review typically identifies several contributing factors rather than one root cause.

One of potentially several true, documented causes that together produced a failure, as distinct from a single exclusive root cause. Serious investigations frequently identify multiple contributing factors operating at different levels of a system (an immediate action, an interface design choice, an organizational or training decision).

A condition that increased the likelihood or severity of a failure but did not, by itself, cause the failure. Most real failures have several contributing factors from different categories that combined at one moment.