Incident Investigation “How-To”


National Safety Council provides an excellent document on how to conduct an incident investigation, and the following is an excerpt.

Your company has just experienced an incident resulting in an injury to a worker. Now what? Reacting quickly to the incident with a prescribed procedure and actions can demonstrate your company’s commitment to safety and ensure the proper information is collected to fulfill an incident investigation’s ultimate purpose – to prevent future incidents.

Steps in an Investigation Process
The investigation process should begin after arranging for first aid or medical treatment for the injured person(s). In getting started, remind everyone involved, especially workers, that the investigation is to learn and prevent, not find fault. Steps of the investigation process include:

  • Call or gather the necessary person(s) to conduct the investigation and obtain the investigation kit.
  • Secure the area where the injury occurred and preserve the work area as it is.
  • Identify and gather witnesses to the injury event.
  • Interview the involved worker.
  • Interview all witnesses.
  • Document the scene of the injury through photos or videos.
  • Complete the investigation report, including determination of what caused the incident and what corrective actions will prevent recurrences.
  • Use results to improve the injury and illness prevention program to better identify and control hazards before they result in incidents.
  • Ensure follow-up on completion of corrective actions.

What to Include in the Documented Investigation Process
As with many processes, preparation and documentation are crucial. As part of the injury and illness prevention program, the investigation procedure should detail:

  • Who should conduct and participate in the investigation.
  • Incidents to be investigated.
  • Information to be collected.
  • Identification of causal factors (often referred to as root causes).
  • Determination of corrective actions.
  • Tracking completion of corrective actions.

Determining Causal Factors / Root Causes
The purpose of this fact-finding is to determine all of the contributing factors as to why the incident occurred. Statements such as “worker was careless” or “employee did not follow safety procedures” don’t get at the root cause of the incident. To avoid these incomplete and misleading conclusions in your investigative process, continue to ask why as in “Why did the employee not follow safety procedures?” Contributing factors may involve equipment, environment, people and management. Questions that help reveal these may include:

  • Was a hazardous condition a contributing factor? (defects in equipment/tools/materials, condition recognized, equipment inspections, correct equipment used or available, substitute equipment used, design or quality of equipment)
  • Was the location of equipment/materials/worker(s) a contributing factor? (employee supposed to be there, sufficient workspace, environmental conditions)
  • Was the job procedure a contributing factor? (written or known procedures, ability to perform the job, difficult tasks within the job, anything encouraging deviation from job procedures such as incentives or speed of completion)
  • Was lack of personal protective equipment or emergency equipment a contributing factor? (PPE specified for job/task, adequacy of PPE, whether PPE used at all or correctly, emergency equipment specified, available, properly used, function as intended)
  • Was a management system defect a contributing factor? (failure of supervisor to detect or report hazardous condition or deviation from job procedure, supervisor accountability understood, supervisor or worker adequately trained, failure to initiate corrective action)

At this point, once you’ve gathered information and interviewed the involved worker and any witnesses, you can prepare the investigation report itself and formulate corrective actions. Each corrective action listed should have a person assigned with ultimate responsibility for the action, a completion date set and a place to mark completion of the item.

For additional information on the investigation process, see the NSC document in its entirety at

Should you require additional assistance with incident investigation training in your workplace, please contact Gary Smith, CRM, at (517) 338-3367 or


  1. National Safety Council Guidance Document: (2014)
  2. OSHA Incident Investigation – A Guide for Employers:
  3. Accident/Incident Investigation Training (PowerPoint):


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