Events Causal Factors Charting

Johnson s interpretation of MES concepts is known as Events Causal Factor Charting (E CF), or Causal Factor Charting for short, and has been adopted as one of the building blocks of several methodologies for process safety incident investigation. 

In the second case study, variation tree analysis and the events and causal factors chart/root cause analysis method are applied to an incident in a resin plant. This case study illustrates the application of retrospective analysis methods to identify the imderlying causes of an incident and to prescribe remedial actions. This approach is one of the recommended strategies in the overall error management framework described in Chapter 8. 

The events and causal factors chart for this incident is shown in Figure 7.9. The primary sequence of events is shown horizontally in bold boxes. Secondary events are shown in the other boxes, and conditions are in ovals. From the diagram three causal factors were identified and carried forward to the Root Cause Coding to establish the root causes of the causal factors. 

Buys, R. J., and Clark, J. L. Events and Causal Factors Charting. Revision 1, Idaho Falls, ID System Safety Development Center, Idaho National Engineering Laboratory, 1978. (DOE 76-45/14 SSDC-14)... 

Sequence diagrams are a more elaborate graphical depiction of a timeline, and allow the investigator to present related events and conditions in parallel branches. These sequence diagrams are also known as causal factor charts. 

These principles are not mandatory. The most important aspect is that the investigator understands the incident, and these principles are meant to facilitate that ohjective. Some investigators draw causal factor charts differently for example, some investigators do not distinguish between events and conditions. It is permissible to violate the above principles provided the method helps the investigator and others understand the incident. 

The first step in developing a causal factor chart is to define the end of the incident sequence. Construction of the chart should start early from the end point and work backward to reconstruct what happened before the incident by identifying the most immediate contributing events. 

Starting at the end point, it is then necessary to convert the collected evidence into statements of either fact or supposition. By taking a small step backward in time, the investigator asks, what happened just before this event. It is important to clearly distinguish any assumptions as supposition. Then the investigator writes a statement for what happened, and enters the fact (or supposition) as an event block or condition oval on the causal factor chart at the appropriate location on the timeline. Statements that caused an event to occur should be treated like conditions and added in an oval. 

Find the facts in the main sequence on the Causal Factor Chart that describe a component failure or a human error. Ensure the fact is not describing a management system failure (i.e., ensure the fact is not a root cause, near root cause, or root cause category). The identified negative events/conditions are candidate causal factors. Any candidate causal factor that is not dependent on another candidate causal factor is a valid causal factor. 

The next phase of investigation involves developing a preliminary chronological description of the sequence of events that led to the failure. Timelines can be developed in various formats and levels of detail, from simple lists of events to complex sequence diagrams or causal factor charts, usually dependent upon the particular circumstances of the investigation being conducted. 

Event and causal factors charts. A mishap investigation tool that graphically depicts the vents and conditions involved in a mishap and illustrates how... 

The event and causal factors charts used by the Department of Energy as an accident (or mishap) investigation tool is basically the same tool as multilinear event sequencing (MES) and similar to simultaneous timed event programming (STEP)—all based on concepts of Ludwig Benner. It is also called causal factors analysis (CFA). 

During the operations phase, new hazards are identified by periodic inspections, worksite monitoring, audits, and appraisals. Techniques used to identify hazards during the operations phase include checklists, PET analysis, and safety studies. Accident analysis is also an important method of detecting previously undetected or uncorrected hazards. Accident analysis tools include change analysis, PET analysis, MORT and mini-MORT analysis, and event and causal factors charts. 

Techniques recommended for conducting accident analysis include change analysis, event and causal factors charts, PET analysis (or MORT or mini-... 

The accident analysis report is a narrative. It includes a description of the project and the accident, a summary of findings and recommendations, an outline of methodology, and a detailed discussion of facts, findings, and recommendations. Photographs, drawings, and an event and causal factors chart are included as illustrations. 

After completely evaluating the chart, cross-check results with the event and causal factors chart and change analysis. Reconcile any differences, use all three tools to aid in writing the formal accident report, and be careful to provide findings, conclusions, and recommendations (backed up with evidence) for each factor deemed to be less than adequate. 

The basic concept from which event and causal factors charts were developed can probably be traced back to Ludwig Benner and others at the National Transportation Safety Board. Benner developed a very similar technique called multilinear event sequencing (MES) and more recently sequentially timed events plotting (STEP). Event and causal factors charts were part of the overall MORT approach to system safety developed by W. G. Johnson for the Atomic Energy Commission in the early 1970s and further developed and taught by the Department of Energy s System Safety Development Center (SSDC). The use of the event and causal factors chart is sometimes referred to as causal factors analysis. 

Event and causal factors charts are graphic representations that basically produce a picture of an accident—both the sequence of events that led to the accident and the conditions that were causal factors. This tool works very well in conjunction with PET or MORT analysis and is used widely in the Department of Energy. 

The purpose of the event and causal factors chart is to provide a systematic accident analysis tool to aid in collecting, organizing, and depicting accident... 

Like other accident analysis techniques, the event and causal factors chart should be initiated as soon as the investigation begins and developed as evidence is collected. A detailed chart is developed during the investigation it is then reduced to an executive summary containing only key events and causal factors to serve as a report illustration. 

Start the event and causal factors chart as early as practical. From the available information, make an event note or card for each event that occurred during the accident sequence and a condition card for each relevant condition that is identified. Organize and reorganize the cards as more information becomes available. 

The rules for developing an event and causal factors chart include... 

The event and causal factors chart is developed and expanded as new evidence and information become available. It should also be developed in conjunction with other analyses (change analysis and PET or MORT analysis), and information should be cross-checked (Fig. 19-2). Conditions that are causal factors on the event and causal factors chart should be identified as less than adequate areas on the PET, MORT, or mini-MORT chart. 

Event and causal factors charts can be relatively simple and straightforward. The complexity of the chart is determined by the complexity of the accident and the desired level of detail. 

Figure 19-3 Example of an event and causal factors chart. This executive summary version of the chart would be included in the formal accident report and used as a briefing tool.

At what point should the event and causal factors chart normally be stopped At what event ... 

---