What are Human Factors? Definitions and Terms.
What are Human Factors?
Those of us in the aviation profession, whether we maintain the aircraft or fly them, have all heard of Human Factors at some point in our career. But do we actually know what Human Factors is? Or, is it, what Human Factors are? If I can’t even decide whether to refer to Human Factors in the singular or plural (or whether or not to capitalize the h and f in Human Factors), perhaps it is worth exploring the definition of Human Factors. The intent of this post is to consolidate and share the bit of knowledge I gained while researching the definition of human factors, and furthermore, to define what we at Sociometri mean by the term(s) human factors. Buckle up, there are a remarkable number of human factors definitions out there.
#TLDR: it depends on who you ask. We like the Transport Canada definition: “Human Factors: Is about people interacting with technology; about people in their working and living environments, and about their relationship with equipment, procedures and living environments. Just as importantly, it is about their relationship with other people. Its twin objectives can be seen as safety and efficiency.”
Perspective
Industry
Anyone who has embarked on a similar quest to understand the definition of human factors (by the way, I’m going with human factors in the singular and lower case for the rest of this post) will likely agree that one of the primary considerations in your definition of human factors is perspective. Specifically, your geographical perspective and your industry perspective are important (note: the regulatory authority given your geography-industry combination is also key factor). Sociometri has roots in the aviation industry, so the industry perspective for us is easy – it’s aviation all the way (<insert Top Gun reference here>). That said, we are always interested in adapting the lessons learned, research, and best practices from other “high operational risk” industries, so we are big fans of borrowing the gems from other areas like nuclear, oil and gas (energy), medical, rail, marine/maritime, and mining, to name a few. We also pay attention to passionate people with an interest in Safety and knowledgeable human factors-related professional associations that are industry-agnostic, such as the Human Factors and Ergonomics Society, for example. But by and large, our industry perspective skews airborne, so we draw a lot from the realms of aerospace and aviation.
Geography
Aviation is a global industry. That is kind of the point. You get in an airplane (or helicopter) to travel from A to B, and A and B can be pretty much anywhere on the planet (okay, they have to be a bit closer together for our rotary-winged friends, but hey – runways optional!). A very cool industry, for sure. That coolness, though, brings about a few challenges when it comes to things like international cooperation and coordination. It also ushers in a slew of opportunities for cultural differences to create challenging situations, as the great people who comprise the aviation industry are from many different places on said planet. Thus placing a rather strong emphasis, in my opinion, on the importance of the human part of human factors for the aviation industry. Having worked the majority of my aviation career outside of my home country, I have a deep appreciation for the power of cultural differences and how they can manifest in an aviation environment. But that is a “whole ‘nother” article. Back to geography…
Fortunately, we in the aviation industry are quite lucky to “stand on the shoulders” of some wise industry pioneers who had the foresight to recognize this global, cultural cooperation challenge back in the day. I am referring of course to the Chicago Convention, more formally, “The Convention on International Civil Aviation” which was written in 1944 (in Chicago, of course) and signed by 54 nations in order to promote cooperation and, “create and preserve friendship and understanding among the nations and peoples of the world (https://icao.int/about-icao/history/pages/default.aspx).” This agreement “established the core principles permitting international transport by air, and led to the creation of the specialized agency which has overseen it ever since – the International Civil Aviation Organization (ICAO).” Here ends the history lesson (or the repetition of an old trope for those coming from an aviation academic environment that referred to this often, like yours truly).
Regulatory Authority
ICAO
The point is, when seeking clarity on the definitions of the term human factors from an aviation perspective, it is wise to consider your geographical perspective and ensure it is in alignment with those of the other professionals you have the privilege of interacting with in your industry. Thus, international organizations with a global perspective, such as ICAO, are a good place to start. So how does ICAO define human factors? Well, it kind of depends on who you ask and where you look. That may come as a bit of a surprise, but grace can be afforded given the sweeping scope of ICAO, and one can only imagine the difficulty in finding consensus among its numerous departments and 193 member States. However, the most useful resource we have found is contained within ICAO Document 10151, its Manual of Human Performance (HP) for Regulators (https://www.icao.int/safety/OPS/OPS-Section/Documents/Advance-unedited.Doc.10151.alltext.en.pdf), which itself admits that, “The terms human performance, human factors, and ergonomics are sometimes confused and are often used interchangeably, even in ICAO documents. This is not surprising because they are closely linked.” Fair point. And to its credit, the document really goes above and beyond by defining not only human factors, but also human performance as follows:
Human Performance (HP) refers to how people perform their tasks. HP represents the human contribution to system performance.
Human Factors (HF) is concerned with the application of what we know about human beings, their abilities, characteristics and limitations, to the design of equipment they use, environments in which they function and jobs they perform.
Upon closer inspection, though, this definition is actually borrowed from another organization. Namely, ICAO adopted this definition from the Human Factors and Ergonomics Society in 2008 (https://www.hfes.org/resources/educational-and-professional-resources/new-item). As noted previously, we don’t fault ICAO at all from citing expertise found elsewhere. In fact, we rather applaud it. Regardless of origin, we now have a pretty solid understanding of what ICAO considers to be human factors. Let’s travel around a bit to see how it stacks up to other definitions of human factors our aviation brethren are using. But first, a few small tangents due to some clarification gems presented in this document by ICAO.
Sidebar on Human Factors vs. Ergonomics
One interesting anecdote in the ICAO Manual of Human Performance (HP) for Regulators was the clarification between ergonomics and human factors, which it notes are also sometimes used interchangeably. The clarification is that ergonomics tends to focus more on the physical aspects of the human, whereas human factors is more often associated with the psychological aspects of the human. Further, it says that in aviation, “ergonomics is considered a subset of human factors that focuses specifically on designing technical systems, products, and equipment to meet the physical needs of the user.”
Another sidebar on Human Factors vs. Human Performance
In the ICAO manual, they prefer to use the overarching term Human Performance (HP), and believe that Human Factors (HF) and ergonomics, “bring insights and understanding to HP from many difference scientific disciplines, such as psychology (including cognitive psychology, industrial and work and organizational psychology, and social psychology), behavioral psychology, sociology, anthropology, medical sciences including aviation medicine and occupational medicine, design and engineering, computer science and statistics.” Since we at Sociometri draw most heavily upon expertise from sociology and behavioral assessment and measurement, we prefer sticking with the term Human Factors. Err, I mean, human factors. So, there you go. Clear as mud.
Okay, onwards on our quest for a universal definition and understanding of human factors in aviation.
IATA
Though not necessarily holding the same clout as a regulatory UN body like ICAO, the International Air Transport Association (IATA) is a good place to check for things that pertain to the entire air transport industry. After all, their mission is, “to represent, lead and serve the airline industry,” (http://iata.org) so why not see what they have to say? Not surprisingly, IATA’s focus is more on selling human factors training courses than defining terms, but even so, they seem to have settled on the following definition of human factors:
“The study of Human Factors is about understanding human behavior and performance. When applied to aviation operations, Human Factors knowledge is used to optimize the fit between people and the systems in which they work in order to improve safety and performance.”
This is pretty good, if a little verbose. Interestingly, the first bullet point of their Human Factors in Aviation course (https://www.iata.org/en/training/courses/aviation-human-factors/tcvt05/en/) is, “Definitions, concepts and history.” So perhaps the key to a universal definition of aviation human factors lies within? If anyone reading this has completed this course, please let us know.
EASA
As an American living in Europe, I must take advantage of the opportunity to start with the European Aviation Safety Agency’s perspective on human factors before diving into the thoughts of the Federal Aviation Administration. Like ICAO, one can probably find multiple definitions or an evolution of the definition of human factors if one was to study all the EASA documentation that mentions human factors. For this post, my preference is to cherry pick my favorite one, which happens to make its appearance in the introductory paragraph of the 2012 document titled, 2012 European Strategy for Human Factors in Aviation,” (https://www.easa.europa.eu/sites/default/files/dfu/sms-docs-EASp-HFP1.1-European-HF-Strategy—1-Sept-2012.pdf), which says that human factors is:
“Anything that affects human performance.”
This is remarkably broad and concise. Later in the strategy document, EASA gives a nod to the human factors terminology struggles afoot, as one of the bullets under Collection and Analysis of Data and Lessons Learnt* states, “Review and revise as appropriate existing Human Factor taxonomies to establish a common understanding of terminology to assist in the further analysis of safety related events by coordinating with existing taxonomy working groups.” In other words, we need some common lingo here. Another gem is the last bullet in this section, which requests, “Cross-fertilisation* of tools and practices across aviation and on aviation activities.” Agree. Any way we can get safer is good for us all.
*Euro-spelling included here for accuracy and authenticity.
FAA
As an American, it was hard to contain my excitement when seeking the enlightenment of the Federal Aviation Administration’s definition of human factors. My hopes were slightly dashed when my initial research seemed to suggest that there isn’t actually one central, harmonized definition of human factors at the FAA. There isn’t even one central department studying human factors at the FAA. Rather, it would appear that there are multiple human factors specialists focused on multiple applications and manifestations of human factors in multiple departments within the FAA. There are human factors initiatives, specialists, research teams, and applications. For example, we have Human Factors in Aviation Safety (AVS), which specialized on promoting, “safety in the National Airspace by working to reduce the occurrence and impact of human error in aviation systems and improve human performance” (https://www.faa.gov/aircraft/air_cert/design_approvals/human_factors). But we also have the Human Factors – Aircraft Certification Service (AIR) (https://www.faa.gov/aircraft/air_cert/design_approvals/human_factors/hf-air), the Human Factors Division NextGen Portfolio Management & Technology Development Office (https://www.hf.faa.gov/), and Human Factors in Aviation Maintenance (https://www.faa.gov/about/initiatives/maintenance_hf), to name a few. One would be forgiven for being a bit overwhelmed by all of this, but rest assured, definition(s) of human factors lie within.
Now, perhaps I am biased because of my maintenance background, but the richness and utility of the FAA’s Human Factors in Aviation Maintenance website is truly remarkable. On its landing page, you will find the word, Definitions, in large, prominent font. Under it is located not only their definition of human factors, but also their definition of safety culture, and a special shout out to the dirty dozen human factors in aviation maintenance (more on that later). Not surprisingly, this is the FAA definition we will prioritize, and it reads as follows,
“Human Factors (HF) is a multidisciplinary field that generates and compiles information about human capabilities and limitations, and applies it to design, development, and evaluation of equipment, systems, facilities, procedures, jobs, environments, staffing, organizations, and personnel management for safe, efficient, and effective human performance.
That’s solid. For fun, here is their definition of safety culture, “A pervasive, organization-wide attitude placing safety as the primary priority driving the way employees perform their work.” That is also very useful. As for the dirty dozen, these are, “the twelve most common maintenance-related causes of errors,” and include: lack of communication, complacency, lack of knowledge, distraction, lack of teamwork, fatigue, lack of resources, pressure, lack of assertiveness, stress, lack of awareness, and norms. Sociometri uses the dirty dozen as a framework by which to measure the human factors culture of aviation organizations in order to improve safety. We explore this in depth, but not here. This is about defining human factors.
Speaking of defining human factors, the astute reader is likely to point to the human factors definition given by the FAA on the paged titled, “The Role of Human Factors in the FAA” (https://hf.faa.gov/role.aspx), which also makes use of the above definition, almost (but not quite) verbatim. Of interest is also the statement directly preceding the definition, as it says, “In the Federal Aviation Administration (FAA), Human Factors is defined as a “multidisciplinary effort to generate and compile information about human capabilities and limitations and apply that information to equipment, systems, facilities, procedures, jobs, environments, training, staffing, and personnel management for safe, comfortable, and effective human performance” (FAA Order 9550.8A).” Forgetting for a second about my use of a quote within a quote, I think this confirms that we have landed upon the FAA’s definition of human factors. Another fun fact, this FAA Order 9550.8A document (https://www.faa.gov/documentLibrary/media/Order/9550.8.pdf) was published in 1993 (and does state the definition of human factors within it), the same year Gordon DuPont is credited with establishing the dirty dozen up north of the US border.
Transport Canada
While we are on the topic of the dirty dozen, and given our passion for Gordon Dupont’s dirty dozen framework (again, more on this another day), there is a special place in our hearts for Transport Canada (for those who don’t know, Gordon DuPont developed the dirty dozen in 1993 while working as an accident investigator for the Canadian CAA (https://skybrary.aero/articles/human-factors-dirty-dozen ). While we will save the Dirty Dozen Deep Dive for another day, Transport Canada has been instrumental in the development of aviation human factors research, education, and awareness. While there are many to choose from, two very helpful Transport Canada human factors documents include Advisory Circular (AC) No. 700-042 ( https://tc.canada.ca/en/aviation/reference-centre/advisory-circulars/advisory-circular-ac-no-700-042) and Human Performance Factors for Elementary Work and Servicing (https://tc.canada.ca/sites/default/files/migrated/hpf_elementary.pdf). AC 700-042 provides the Transport Canada definition of human factors in section 2.3.1.o.,
“Human Factors: Is about people interacting with technology; about people in their working and living environments, and about their relationship with equipment, procedures and living environments. Just as importantly, it is about their relationship with other people. Its twin objectives can be seen as safety and efficiency.”
Interestingly, TC then cites ICAO Circular 227, which upon further investigation is a reference to 1991 ICAO Circular 227-AN/136, Human Factors Digest No. 3, Training of Operational Personnel in Human Factors (https://news.mcaa.gov.mn/uploads/bookSubject/2022-09/63101b2db08f8.pdf). We will take a closer look at this gem another day, but one line about the definition of human factors already caught our eye, “In spite of the academic sources of information on the various Human Factors disciplines, aviation Human Factors is primarily oriented towards solving practical problems in the real world.” This is what Sociometri is all about, solving real human factors and safety culture problems in organizations by measuring their human factors.
The second (3rd?) Transport Canada document we love is Human Performance Factors for Elementary Work and Servicing. While less focused on the definition of human factors, this no-frills document lays out the “Factors Affecting Human Performance,” a.k.a. the dirty dozen, as: Lack of Communication, Complacency, Lack of Knowledge, Distraction, Lack of Teamwork, Fatigue, Lack of Resources, Pressure, Lack of Assertiveness, Stress, Lack of Awareness, and Norms.” They then discuss each of the 12 items in more detail, and conclude the document with two case study examples. The plain, concise language combined with relevant examples make this document stand out compared to many other human factors publications from the regulatory authorities of aviation. As a primer into aviation human factors and the dirty dozen, this one takes the cake.
UK CAA
Given this is a quest to define two simple English words, human and factors, one would be wise to turn to the Brits* for their guidance – having invented the language and all. However, one might be slightly disappointed. At least I was when I discovered that this very promising 38-page text titled, “CAP 719 Fundamental Human Factors Concepts” (https://publicapps.caa.co.uk/docs/33/cap719.pdf) fails to settle on defining human factors, despite spending an entire chapter on it (Chapter 1: The Meaning of Human Factors). Now, it should be said that after reading this chapter you will definitely have a better understanding of what human factors means, but it should also be said that there is not one, true, universal definition presented within. Good concepts, yes, but on the extreme opposite end of the brevity spectrum as the aforementioned EASA take. Here, little is said with a lot.
*Yes, I did catch that CAP719 was previously published by ICAO as Circular number 216-AN/131, but it was more fun to attribute it fully to the UK.
Other Aviation Regulatory Authorities
Acknowledging that most countries have their own state-level civil aviation authority, and there are many countries in the world, I thought it pragmatic to conclude my research at this point for now. Alas, as a human factors practitioner my intent here was not to “develop a new taxonomy” for human factors for EASA, but rather to shed some light on these simple terms we so often use and to ensure we at Sociometri exercise at least a reasonable level of precision when we wield them. And for that, I believe we have reached a satisfactory level of understanding. I apologize in advance if I have offended someone with my choice of CAAs to highlight. Note that I have done more reading than what I opted to reflect in this post, but by all means please let me know if there is a fantastic definition of human factors just waiting for me in the guidance documents of another authority.
Other Industries / Perspectives
Returning to the concept mentioned in the beginning, the most useful definition of human factors is likely to be influenced by the lens through which you view the world. When discussing and presenting human factors, I have found the Venn diagram below to be a helpful starting point. Our understanding and definition of the term human factors likely lies at the middle of the intersection of Industry, Regulatory Authority, and Geography.
As you now know, our industry perspective is inclusive of many high operational risk industries, but the foundation is aviation. As such, I focused my prior rambling with the geographical tour of aviation regulatory authorities, and omitted discussion of other industries. This is both because my academic background and professional experience comes from aviation, and because this post is already 10 times too long for anyone to read. So, at risk of disappointing those readers who have made it this far and were looking forward to hearing my thoughts about other industry perspectives, I think I will cut it here for now. But as a reward for those of you who made it this far, here are a few gems I found while doing this research (Legal, Medical, Nuclear) (https://lawinsider.com/dictionary/human-factors. https://chfg.org/what-are-clinical-human-factors/ https://arpansa.gov.au/regulation-and-licensing/safety-security-transport/holistic-safety/human-factors . We are also embarking on a rather significant amount of work with mining companies, so stay tuned for more insights into the lessons learned from deploying Sociometri in the mining industry.
Feedback
I would love to hear your thoughts on this post, human factors, terminology, or anything related to improving safety culture in organizations. Please give me a shout!