A lot is written about incident investigations and how to perform an effective one. Here are some insights and hints from our experience performing investigations.
All evidence will not be forthcoming unless the investigation is blame free.
First obtain a general picture of the incident, visit the scene , take pictures.
For a serious incident, carry out interviews ASAP. Memories fade rapidly
Separate witnesses. Once witnesses have interacted, a communal view will prevail.
Witness evidence is notoriously unreliable.
Witness evidence from before the incident is less reliable than that from immediately after the incident.
Witnesses sometimes remember the incorrect
“Then the relief valve on the high pressure boiler lifted” A later study of the DCS trends and alarm information showed clearly it was a vent valve on a process gas system.
Witnesses are influenced by guilt and will rationalise their own actions and be concerned about implicating colleagues
As an interviewer, you will need to be persistent and at times recycle facts uncovered in the analysis to get to the truth.
Develop a timeline based on facts.
Collect physical evidence, take photos, permits, mark location, collect control data, procedures, training records, maintenance records.
Remember in the event of a serious injury or fatality, the scene must not be disturbed without approval from WorkSafe or the Police – unless there is an immediate ongoing danger to life or essential services.
Collate and analyse the evidence to develop alternative scenarios leading to the immediate causes, then progress to the root causes. Remember “All incidents are the result of management failures”. To quote Trevor Keltz –"blaming human error as the cause of an incident is about as useful as blaming gravity as the cause of a fall".
Propriety tools are available, some of which can be quite useful in leading to root causes, others are fine for investigating a fall from a ladder but not very helpful with an incident involving complex technology.