Text-only reference. Published from the recorded official FAA General Chapter 14 PDF. Diagrams, photographs, and figure artwork are not reproduced here; use the official FAA PDF for those materials.
14-1
Human Factors
Chapter 14
Introduction
FAA Involvement The FAA has had a formal involvement in this issue since 1988. That was the year the first Human Factors Issues in Aviation Maintenance and Inspection National Conference was conducted, and that effort reflects a working relationship between government research and industry activity. This yearly event includes airlines, suppliers, manufacturers, schools, and government agencies. There is also an FAA website for human factors at hf.faa.gov which is a tremendous resource. Importance of Human Factors The greatest impact in aircraft safety in the future will not come from improving the technology. Rather it will be from educating the employee to recognize and prevent human error. A review of accident related data indicates that approximately 75–80 percent of all aviation accidents are the result of human error. Of those accidents, about 12 percent are maintenance related. Although pilot/co-pilot errors tend to have immediate and highly visible effects, maintenance errors tend to be more latent and less obvious. However, they can be just as lethal.
Definitions of Human Factors Human factors are concerned with optimizing performance … including reducing errors so that the highest level of safety is achieved and maintained. —Ron LoFaro, PhD FAA Human factors is the study of how people interact with their environments. —FAA-H-8083-25, Pilot’ s Handbook of Aeronautical Knowledge Human factors are those elements that affect our behavior and performance, especially those that may cause us to make errors. —Canadian Department of Defense (video) Our focus is on human factors as it relates to improper actions. Note, however, that human factors exist in both proper and improper actions. [Figure 14-1] Since improper actions usually result in human error, we should also define that term.
Human error is the unintentional act of performing a task incorrectly that can potentially degrade the system. There are three types of human error: 1. Omission: not performing an act or task. 2. Commission: accomplishing a task incorrectly. 3. Extraneous: performing a task not authorized. There are also four consequences of human error: 1. Little or no effect. 2. Damage to equipment/hardware. 3. Personal injury. 4. Catastrophic. Why are human conditions, such as fatigue, complacency, and stress, so important in aviation maintenance? These conditions, along with many others, are called human factors. Human factors directly cause or contribute to many aviation accidents. It is universally agreed that 80 percent of maintenance errors involve human factors. If they are not detected, they can cause events, worker injuries, wasted time, and even accidents. [Figure 14-2] Aviation safety relies heavily on maintenance. When it is not done correctly, it contributes to a significant proportion of aviation accidents and incidents. Some examples of maintenance errors are parts installed incorrectly, missing parts, and necessary checks not being performed. In comparison with many other threats to aviation safety, the mistakes of an aviation maintenance technician (AMT) can be more difficult to detect. Often, these mistakes are present but not visible and have the potential to remain latent, affecting the safe operation of aircraft for extended periods of time.
AMTs are confronted with a set of human factors unique within aviation. They can be working in the evening or early morning hours, in confined spaces, on high platforms, and in a variety of adverse temperature/humidity conditions. The work can be physically strenuous, yet it also requires attention to detail. [Figure 14-3] Because of the nature of maintenance tasks, AMTs commonly spend more time preparing for a task than actually carrying it out. Proper documentation of 14-2
Human Factors
Active Failure Latent Failure Assertiveness Leadership Asynchronous Communication Maintenance Resource Management Authoritarian Leader Mental Model Communication Norms Complacency Participatory Leader Crew Resource Management Safety Culture Dirty Dozen* Situational Awareness Egalitarian Stressor Ergonomics Synchronous Communication Human Factors Team Inter-team Team Situational Awareness Intra-team Teamwork Instructional Systems Design * 1. Lack of Communication 2. Complacency 3. Lack of Knowledge 4. Distraction 5. Lack of Teamwork 6. Fatigue 7. Lack of Resources 8. Pressure 9. Lack of Assertiveness 10. Stress 11. Lack of Awareness 12. Norms
Human Factors
Proper Actions Improper Actions HF applies to both all maintenance work is a key element, and AMTs typically spend as much time updating maintenance logs as they do performing the work. [Figure 14-4] Human factors awareness can lead to improved quality, an environment that ensures continuing worker and aircraft safety, and a more involved and responsible work force. The reduction of even minor errors can provide measurable benefits including cost reductions, fewer missed deadlines, reduction in work related injuries, reduction of warranty claims, and reduction in more significant events that can be traced back to maintenance error. Within this chapter, the many aspects of human factors are discussed in relation to aviation maintenance. The most common human factors are introduced along with ways to mitigate the risk to stop them from developing into a problem. Several Federal Aviation Administration (FAA) human factor resources are provided, including a direct link to aviation maintenance human factors are at hf.faa.gov.
What are Human Factors?
The term “human factors” has grown increasingly popular as the commercial aviation industry realizes that human error, rather than mechanical failure, underlies most aviation accidents and incidents. Human factors science or technologies are multidisciplinary fields incorporating contributions from psychology, engineering, industrial design, statistics, operations research, and anthropometry. It is a term that covers the science of understanding the properties of human capability, the application of this understanding to the design, development, and deployment of systems and services, and the art of ensuring successful application of human factor principles into the maintenance working environment.
The spectrum of human factors that can affect aviation maintenance and work performance is broad. They encompass a wide range of challenges that influence people very differently as humans do not all have the same capabilities, strengths, weaknesses, or limitations. Unfortunately, aviation maintenance tasks that do not take into account the vast amount of human limitations can result in technical error and injuries. Figure 14-5 shows some of the human factors that affect AMTs. Some are more serious than others but, in most cases, when you combine three or four of the factors, they create a problem that contributes to an accident or incident.
Elements of Human Factors Human factors are comprised of many disciplines. This section discusses ten of those disciplines: Clinical Psychology, Experimental Psychology, Anthropometrics, Computer Science, Cognitive Science, Safety Engineering, Medical Science, Organizational Psychology, Educational Psychology, and Industrial Engineering. [Figure 14-6] The study and application of human factors is complex because there is not just one simple answer to fix or change how people are affected by certain conditions or situations. The overall goal of aviation maintenance human factors research is to identify and optimize the factors that affect human performance in maintenance and inspection.