The Four Basic Components of an Accident Investigation

The four basic components of the accident investigation process are:

• The accident sequence.
• Human factors accident and incident analysis.
• Equipment factors analysis.
• Environmental factors analysis.

The nature and complexity of the accident determines the extent to which these components are evaluated.

Accident Sequence

The accident sequence consists of five components and is established based only on the facts determined during the investigation. The five components are:

• Events occurring before the accident. Establish the sequence of events leading to the accident to answer the questions: who, what, when, where, and how. Identify any contributing factors such as urgency, weather, equipment condition, or terrain. If a fire was involved, establish when, where, and how the fire was started. Determine flame propagation and whether attempts were made to extinguish the fire.
  
  
• The accident sequence. Start with the initiating event (examples are the truck tire blew out or the helicopter tail rotor struck a snag) and continue until the sequence reaches a logical endpoint.
  
  
• Events occurring after the accident. Identify the sequence of events that occurred after the accident (such as search and rescue or medical efforts), how the accident was first reported, and the locations of personnel and equipment after the accident. Note any disturbance to the accident site and security or preservation measures taken, as well as any injury and causal or contributing factors due to events that occurred after the accident, such as rescue and medical response.
  
  
• Injuries. Record all injuries. Identify all medical facilities that provided treatment, document the condition of the patients, and summarize autopsy reports, if applicable.
  
  
• Damage. Estimate the cost of the equipment or property damage and define the damage as minor, major, destroyed, or repairable.

Human Factors Accident and Incident Analysis

Human factors play a large role in most accidents. Investigators need to be able to identify the human factors that contribute to an accident. Thorough analysis can result in effective intervention and prevention strategies and recommendations.

1. Qualifications and Training. Determine the qualifications and training of individuals directly involved in the accident (the vehicle operator, passengers, and supervisor). Identify any contributing factors such as the lack of operator certifications or insufficient training.
   
   
2. Duties. Identify the duties of individuals directly involved in the accident, such as primary and additional duties, and work and rest schedules. Note any contributing factors, such as employee fatigue. Conduct a work/rest analysis covering at least 72 hours before accident. Include an examination of time and attendance records as well as input from appropriate supervisors on tasks completed and actual time worked (may not necessarily match recorded time), offduty activities, and sleep duration cycles.
   
   
3. Management. Determine the organization, supervision, and external control of individuals directly involved in the accident. Identify any contributing factors, such as a failure to emphasize safety by the supervisor or organization.
   
   
4. Compliance. Note deviations from policies, procedures, practices, and contract specifications. Review the JHA, safety equipment, and other items pertinent to the accident investigation.
   
   
5. Documents. Identify whether directives, operating guides, and contracts were current, readily available, and properly used by individuals associated with the accident. Review records specific to the accident, such as inspections, dispatch and equipment logs, time and attendance records, safety plans, and incident command system forms, if applicable.
   
   
6. Communications. Identify the type of communications used before, during, and after the accident. Identify any contributing factors related to communications, such as radio coverage or faulty equipment.
   
   
7. Services. Determine whether contractual services, such as road guards, traffic signs, or dispatch procedures contributed to the accident.
   
   
8. Risk Management. Determine whether a JHA or other workplace risk analysis was developed. Establish the role that the risk analysis played in the performance of the work project or activity. Determine whether a tailgate safety session was held and documented before work began.

Equipment Factors Analysis

1. Systems. Determine what equipment was involved in the accident and its suitability to perform the work project or activity. Include any pertinent operator manuals, maintenance records, inspections, and approvals of maintenance personnel.
   
   
2. Survivability. Evaluate the ability and suitability of the vehicle, system, or equipment to perform the work project or activity, and the structural integrity of the occupant compartment.
   
   
   • Impact conditions and crash (dynamic) forces.
   • Restraint and rollover protection systems. Were such systems installed? Were they used?
   • Personal protective clothing and equipment, and safety equipment.
   • Backup and emergency systems.
   • Safety design.
     
     
3. Laboratory or Teardown Analysis. Review the results of any equipment component analyses. Special studies or tests should be conducted by another agency or private laboratory.

Environmental Factors Analysis

1. Weather. Verify the weather conditions before, during, and after the accident. Identify any contributing factors, such as precipitation, temperature, lighting, and visibility.
   
   
2. Physical Environment. Fully describe the accident scene. Determine whether the scene was preserved. Note the terrain at the accident site. Provide a general area map, a site-specific location map, profiles of terrain features, diagrams and sketches of the accident site, and diagrams of any other relevant objects. Take all measurements from a control point that has some permanency. Measurements can be made from the control point during return trips to the site. Identify any contributing factors, such as altitude, vegetation, slope, accessibility, dust, and smoke.

Source: U.S. Forest Service