What questions should I ask during the incident investigation?

Effective incident investigations don’t stop at identifying a single factor that triggered an incident. They ask the questions “Why?” and “What led to the failure?” For example, if a piece of equipment fails, a good investigator asks: “Why did it fail?” “Was it maintained properly?” “Was it beyond its service life?” and “How could this failure have been prevented?” A good incident investigation does not stop when it concludes that a worker made an error. It asks such questions as: “Was the worker provided with appropriate tools and time to do the work?” “Was the worker adequately trained?” and “Was the worker properly supervised?”