Human factors and aircraft maintenance

Flying Safety,  August, 2004  by Anthony Wurmstein,  Michael Shetler,  Jeff Moening

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Human factors and aircraft maintenance, what's a maintainer to do? If you look at past mishaps, we spend a lot of time looking at aircrew human factors, but what about the person turning the wrench and making the aircraft fly? They are a human factor, and the Air Force needs to look at how we can prevent the maintenance human factor mishap. We hope to provide you with some information that you, the supervisor and the individual, can use to help understand human factors in aircraft maintenance.

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What is Human Factors?

Human factors is the science of analyzing the limitations of humans as we interact with the environment and preventing or mitigating the inevitable human error. The limitations of humans come in five flavors and are known as the Five Ps: Physical (heat, cold, etc.); Physiological (oxygen, blood flow, etc.); Psychological (senses, information processing, etc.); Psychosocial (team interaction, communication, etc.) and Pathological (illness, injury). Each of these areas is a profession by itself, but together they make up the field of human factors. Human factors lets us look at not just individual human failures but the failures in the systems that we humans create. "OK," you say. "That's all great, but how does it help me?" Well, in order to analyze these failures and develop strategies to prevent them, you need a structure or "taxonomy" to organize the different types of failure.

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What Is the Human Factors Taxonomy?

This is how we apply human factors to a mishap to determine the cause of the human failure or error that contributed or led to the mishap. If you look at the human factors taxonomy charts (Charts 1-4), you can see we start at the organizational influences and work our way down to the individual acts. This ensures we look at all aspects of the mishap to find the root cause--not the easy answer.

We start by looking at organizational influences or culture (Chart 1). These are the factors in a mishap where the decisions of upper-level management directly affect supervisory practices, conditions and actions of the operator, and result in system failure, human error or unsafe situation. This could be resource management or acquisition, organizational climate or organizational process.

These factors apply when upper-level management sets up or fails to provide an adequate safety environment, structure, policies, procedures or equipment that influences individual actions and results in human error or an unsafe condition. The processes fail when operations, procedures, ORM and oversight negatively influence individual, supervisory, and/or organizational performance and results in unrecognized hazards and/or an uncontrolled risk. Have you ever heard of a mishap where the cause was a procedure that was overlooked as being wrong until the mishap? It happens every year and even cost one maintainer his life.

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The next level is supervision, which is a factor in a mishap if the methods, decisions or policies of the supervisory chain of command directly affect practices, conditions, or actions of individuals and results is human error or an unsafe condition (Chart 2). The main aspects of the supervision factors are inadequate supervision, planned inappropriate operations, failure to correct a known problem and supervisory violations.

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How do we define inadequate supervision? In a mishap sequence, it would be when supervision proves to be inappropriate or improper, and fails to identify a hazard, recognize or control a risk, provide guidance, training and/or oversight that result in human error or an unsafe situation. How about when supervision is supposed to perform an In-Process Inspection and doesn't?

The next supervisory item is planned inappropriate operations. This is a factor in the mishap sequence when supervision fails to adequately assess the hazards associated with an operation and allows for unnecessary risk. Additionally, supervision may allow non-proficient or inexperienced personnel to attempt missions/tasks beyond their capability or when crew or flight makeup is inappropriate for the task or mission assigned. We had one mishap during an engine run where supervision planned an engine run operation that ended up with the aircraft jumping chocks.

Another factor is failure to correct a known problem. This is when supervision fails to correct known deficiencies in documents, processes or procedures, or fails to correct inappropriate or unsafe actions of individuals and this lack of supervisory action creates an unsafe situation. How often do we hear, "This is the way we have always done it?" Too often! Supervisors knew the people were violating the rules, or supervision said to violate the rule, and nothing was done to prevent the mishap. How many cases are out there today where supervisors watch a young inexperienced troop do things wrong and don't correct them on the spot? This sets the person up for failure in the future.