Mishap causal factor

Accident cause refers to the causal factors resulting in an accident or mishap. To better understand accident causes, see the definition for Hazard, which describes the components of a hazard. Accidents and mishaps cannot occur unless a hazard preexists and the hazard components establish the associated mishap causal factors. 

Accident investigation is the determination by qualified personnel as to the specific causing for a particular accident or mishap. Causal factor considerations include management errors, technical design, hardware failures, procedural errors, and so on. An accident investigation can be conducted by a formal board or by an informal analysis performed by one or more individuals. 

HCFs are the specific causes of a hazard. HCFs are the genesis of a mishap they explain how a hazard will transform into a mishap, and they also explain what outcome to expect. Hazard-mishap theory states that hazards create the potential for mishaps, mishaps occur based on the level of risk involved, and risk is calculated from the hazard-mishap causal factors. HCFs are the unique factors that create the hazard, while mishap causal factors are the factors that cause the dormant hazard to become an active mishap event. 

Just as hazard risk is the same as mishap risk, HCFs are the same as mishap causal factors. 

For a hazard to exist, three hazard components must be present (1) the HS which provides the basic source of danger, (2) the potential IMs that will transition the hazard from an inactive state to a mishap event, and (3) the TTO that will result from the expected mishap event. The HS and IM are the HCFs that are used to determine risk likelihood, and the TTO is the causal factor that estabhshes risk outcome and severity. The HS and IM hazard components can be broken into the major causal factor categories of hardware, software, humans, interfaces, functions, procedures, management safety culture, and the environment. Since hazard risk is the same as mishap risk, HCFs are also mishap causal factors because they are the same factors used to compute the risks. 

Mishaps involve a set of causal factors that lead up to the final mishap event, and these factors are the actuated hazard conditions. Mishap causal factors can be identified prior to an actual mishap through the application of HA. Mishaps are an inevitable consequence of antecedent causes and, given the same causal factors, the same mishap is repeatable, with the frequency based on the component probabilities. Mishaps can be predicted via hazard identification, and they can be prevented or controlled via hazard elimination or hazard control methods. This safety concept demonstrates that we do have control over the potential mishaps in the systems we develop and operate. We are not destined to face an unknown suite of undesired mishaps, unless we allow it to be so (by not performing adequate system safety). In the safety sense, mishaps are preplanned events in that they are actually created through poor design and/or inadequate design foresight. 

A hazard is a wrapper containing (or describing) all of the latent conditions (or components) necessary to result in a mishap, when the latent factors actualize. And, the hazard wrapper also describes the mishap outcome to be expected. The major difference between a hazard and mishap description is how they are stated a hazard could happen whereas a mishap did happen. In addition, a hazard is stated with all the necessary elements as a potential condition, while a mishap is only stated as the final outcome (which is defined in the hazard statement). It is interesting to note that when a mishap actually does occur, it is the job of the accident investigation team to discover all of the mishap causal factors, which in effect describes the hazard components that should have originally been identified. 

It has been found that simple mishaps tend to be complex in terms of many causal factors with lengthy sequences of errors and changes leading to the various events. This makes it essential for the investigator to have a system, a methodology for breaking down the entire sequence of events into individual events with supporting information [p. 159]. 

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). 

Causal Factors column A description of why or how the hazard may result in a mishap. 

System safety methods assume that accidents and mishaps result from multiple causal factors. System thinking views hazards and causal factors as moving in logical sequences to produce accident events. Traditional approaches to accident prevention simply classify causal factors as unsafe acts and unsafe conditions. Hazard control personnel should use root cause processes to discover, document, and... 

Root Cause Analysis analysis that identifies causal factors relating to a mishap or near-miss incidents. 

The purpose of the Root Cause Analysis is to identify causal factors relating to a mishap or near-miss incidents. The technique goes beyond the direct causes to identify fundamental reasons for the fault or failure. 

Hammer s message was important for me. He made plain that it would be advantageous in the practice of safety to look for root causal factors that occur above the level of the worker who may have been involved in a mishap. 

It is commonly said in the literature, as Ted Ferry (1981) did in Modem Accident Investigation and Analysis An Executive Guide, that the supervisor is closest to the action, that the mishap takes place in the supervisor s domain, and that initial responsibility for investigation is very often assigned to the supervisor (9). Ferry went on to say that being close to a situation may preclude a supervisor from taking an unbiased approach to causal factors that may reflect on his own performance or that of people to whom he reports (9). 

To illustrate the HCF concept, consider the hazard Fire destroys a house due to ignition of a gas leak. The HCFs are flammable gas and faults that cause leaking and ignition of the gas. The house is destroyed because a fire resulted from ignited gas. The mishap is the destroyed house, caused by an explosion and fire, caused by gas ignition. For this particular hazard, all of the causal factors must be ANDed together gas present in system, gas leak occurs, and gas ignition source occurs. 

MORT is an analysis technique for identifying SR oversights, errors, and/or omissions that led to the occurrence of a mishap. MORT is primarily a reactive analysis tool for accident/mishap investigation, but it can also be used for the proactive evaluation and control of hazards. MORT analysis is used to trace out and identify all of the causal factors leading to a mishap or UE. MORT utilizes the logic tree structure and rules of FTA, with the incorporation of... 

An industry standard definition of mishap, provided in MIL-STD-882D, is An unplanned event or series of events resulting in death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment. It should be noted that in system safety, the term mishap is synonymous with accident. A mishap is effectively an actualized hazard, whereby the hazard transitions from the dormant conditional state to the active mishap event state. The three required components of a hazard predefine the mishap. A mishap would not be possible without the preexistence of a hazard. A mishap is an actual event that has occurred and has resulted in an undesired outcome. Mishaps and a hazards are directly related, they are linked together by risk and state space. A mishap is an actuated hazard it is the direct result of a potential hazard, when the hazard s IMs (or causal factors) occurs, transitioning the hazard from a potential condition state to a mishap event state with loss outcome. 

Identify new hazards and their causal factors by evaluating the subsystem hardware components and software modules. Use analysis aids to help recognize and identify new hazards, such as TLMs, hazard checklists, lesson learned, mishap investigations, and hazards from similar systems. 

A TLM is a generic mishap category for collecting together various hazards that share the same general outcome or type of mishap. A TLM is a common mishap outcome that can be caused by one or more hazards its purpose is to serve as a collection point for of aU the potential hazards that can result in the same outcome, but have different causal factors. TLMs provide a design safety... 

The real value and need for TLMs is based on the need for system hazard clarity and focus. The use of TLMs helps to resolve some safety programmatic issues, such as (a) hazard abundance, (b) hazard confusion, (c) subsystem confusion, and (d) total mishap risk. As HAs are performed on a system design, many hazards are identified, sometimes in the thousands. With a large number of hazards, it often becomes difficult to maintain hazard visibility. Sometimes hazards are inadvertently repeated sometimes hazards are stated as causal factors rather than hazards. Hazard risk can be assessed against TLMs to determine if a thread exists that creates increased risk for that TLM category. 

X-tree analysis is an analysis technique that combines FTA and ETA together to evaluate multiple possible outcomes from a UE. The various outcomes result from the operation or failure of barriers intended to prevent a mishap. The analysis begins with identification of the IE of concern in the center. An FTA is performed to identify the causal factors and probability of this event. Then an ETA is performed on all the barriers associated with the IE, and the possibilities of each barrier function failing. The various different failure combinations provide the various outcomes possible, along with the probability of each outcome. X-tree analysis is also referred to as bow-tie analysis. 

---