This paper presents study of 115 grounding accident reports from the Safety Investigation Authority of Finland and Marine Accident Investigation Branch of the UK, as well as 163 near-miss grounding reports from ForeSea and Finnpilot incident databases. The objective was to find the type of knowledge that can be extracted from such sources and discuss the usability of accident and incident reports for evidence-based risk modeling. A new version of Human Factors Analysis and Classification System (HFACS) is introduced as a framework to review the accident reports. The new positive taxonomy as Safety Factors, which are based on high level positive functions that are prerequisite for safe transport operations, is used for reviewing the incident reports. Accident reports are shown as a reliable source of evidence to extract the most significant contributing factors in the events. Mandatory incident reports are considered useful for understanding the effective barriers as risk control measures. Voluntary incident reports, though, are seen as not very reliable in their current form to be used for evidence-based risk modeling.
It is often helpful to see an example of an accident investigation in order to better understand how the process works. Here is a simple accident investigation case study.
This is the accident scenario:
- An employee is working on a ladder and the ladder seems to collapse.The employee falls off the ladder and breaks arm.
The investigation reveals the following details:
- Employee had worked seven 12-hour shifts in a row.
- Accident happened at end of shift.
- Employee was standing on the top step of the ladder (an unsafe action).
- The employee was approximately 10 feet above floor level.
- No fall arrest or restraint system was used.
- A ladder inspection policy is in place, but there is no evidence that the ladder has ever been inspected.
- Investigation reveals the ladder was damaged and did not provide a stable working platform in any environment.
- Interview with facility manager reveals that he did not inspect the ladder when it was due for inspection. He was aware that ladder needed to be inspected.
Factors and Possible Causes Affecting Incident
- Extended work hours may have caused employee to be tired and not clear-headed.
- Employee violated safety rule (standing on top step).
- No fall arrest system in place (required at 6 feet above floor level).
- Ladder was defective and unusable.
- Ladder had not been inspected.
- Facility manager was aware that ladder needed to be inspected but did not adhere to the existing policies and procedures for ladder inspections.
What is the Root Cause?
Which factor, if not present, could have prevented the accident?
If the facility manager had inspected the ladder and discovered the defect, the ladder would not have been used, and this accident would have been prevented.
Failure to follow established ladder inspection procedures is the root cause.
What about the Other Factors?
- Extended work hours might contribute, but there is no statistical evidence available that indicates extended work hours increase the risk of accidents.
- The safety rule violation could be a contributory cause in this accident, but not the root cause. However, if the ladder had been used properly, it is possible that the incident might have been prevented.
- •The existence of a fall arrest system may have prevented or reduced injury. This could be a contributory cause.
- The fact that the ladder was defective is certainly a contributory cause. But if the facility manager had followed procedures and removed the ladder from service, the accident would have been prevented.
The root cause of this accident could even be tracked deeper than just finding the facility manager’s failure to inspect the ladder. With more in-depth analysis, it might be found that the real cause was a failure in the system itself. Perhaps the safety system in place had no means of ensuring the facility manager actually carried out these inspections.
It is for reasons like this that accident investigations are best conducted by a team. This can ensure that as many possibilities are explored until all causes are discovered. It is easy to place blame on individuals when in actuality, the problem may be with your management systems.