Human Factors in the Training of Pilots

Jefferson M. Koonce

• Publisher: CRC Press
• Year: 2002
• ISBN:
  9781134525102
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Industrial Engineering
• Index: Technology & Engineering

In this educational yet entertaining text, Jeff Koonce draws on his 44 years of pilot experience and 31 years as a professor of psychology and human factors engineering in addressing the questions of how to apply sound human factors principles to the training of pilots and to one's personal flying. The author discusses principles of human f

Part I
Human factors

1 Human factors

Scope of human factors

As the name implies, the topic, human factors, is about humans and how they interact with their environment and things within that environment. A definition that I have used for many years is as follows:

Human factors is the study of the human’s capabilities, limitations, and behaviors and the integration of that knowledge into the design of things, places, and environments in which people live and work for the enhancement of the person’s efficiency, safety, and general well-being.

The first part of this definition involves the understanding of the human, and the second half is the application of that knowledge in improving the human-machine system’s performance and making life better for people. In Europe, the term “ergonomics” has been the term used for what we call “human factors,” and that term, ergonomics, has become more popular in the United States over the past 10 years.

Actually, very little could be considered beyond the scope of human factors. For no matter what an engineer designs, somehow or somewhere humans will interact with it, and to the extent that a failure in that interaction may affect system performance or the human in some adverse manner, human factors must be considered in that design.

Background

Human factors, that is, the need for consideration of the human’s needs for information, proper controls, and personal safety in the flying of an airplane dates back to the earliest airplanes (Koonce 1984a, 1999). In the realm of flight, the human’s capability to sense information was being exceeded, and devices and instruments had to be developed to provided needed information to the pilot. The pilot could not directly sense the angle of attack of the wing(s), critical to the difference between flying and stalling the wing. So, the Wright brothers developed an incidence meter that indicated the angle of the wing with respect to the flow of air (relative wind). Uncoordinated flight could easily put the airplane in a spin, so a string or yarn was tied to one of the struts of the airplane in such a manner that the pilot could see whether or not the airflow was parallel to the longitudinal axis of the airplane.

As flights became longer and were performed at higher altitudes, the human’s ability to make needed discriminations in heading, velocity and altitude was exceeded. Thus, magnetic compasses were carried over from maritime applications to airplanes, and airspeed indicators and altimeters were developed to provide height and velocity information to the pilots.

Because of the unreliability of the propulsion systems (engines and propellers) tachometers were developed for better control of the engine speed and stresses upon the propeller. Also, information was provided regarding the engine temperature and lubrication so that the pilot would not cause harm to the engine that could result in its failure.

Other human factor considerations were with the protection of the pilot. On 17 September 1908, US Army Signal Corps Lieutenant value of the Wright’s airplane. When a guywire broke, causing damage to one of the propellers, the airplane crashed. Orville Wright suffered a broken thigh and two broken ribs, but his passenger, Lieutenant Selfridge, died of a fractured skull; the first person to die in powered flight. Subsequent airplane designs began to include seat belts to secure the pilot and passenger(s).

Initially, the pilot was not shielded from the environment when piloting the airplane. Protection from the elements took the form of goggles, gloves, and topcoats similar to those used in driving the automobiles and motor cycles of that era. Later models of airplanes had streamlined fuselages in which the pilot was located in a cockpit, open or enclosed. As the airplanes’ performance capabilities advanced so did the need for additional information to be presented to the pilots.

In the early days of aviation, the airplanes and their subsystems were not very reliable, and most of the aircraft accidents were attributable to some mechanical failure or design flaw. There were many instances of power loss due to the failure of the engine, the propeller, or the quality of the fuel. There were also numerous accidents due to structural failure of the wings, empennage or fuselage or the inherent instability of the aircraft’s design. Over the past 50 or 60 years, the physics and mechanics related to aviation have rapidly evolved. The result has been that the mechanical components of airplanes have become much more reliable, so much so, that the major contributor to today’s accidents and incidents is the human element. The National Transportation Safety Board (NTSB) suggests the pilot as the causal factor in about 80 percent and Jensen (1995) says that human error accounts for 80 percent of general aviation accidents and 70 percent of the commercial aviation accidents. Thus, a very large portion the aviation accidents and incidents could have been prevented through the proper application of the principles of human factors.

Chambers and Nagel (1985) noted the fact that the refinements in the machines (technology) over the years has resulted in the number of aviation accidents caused by the “machine” to decline while those attributed to the human have risen proportionately (see Figure 1.1).

However, the Air Safety Foundation’s Safety Advisor (1998b: 1) states that “The root cause of mechanically induced accidents is almost always neglect.” Neglect infers the behavior of a human in the chain of events that lead to an accident or incident. Thus, it is reasonable to assume that in most of the mechanical failures in aviation accidents the pilot, maintenance person, or others might have noted a potential failure, but decided that it might not be too serious, or it might last a little longer. This is rather typical with wearing of tires and brakes, nicks in the propeller, and various engine signals of impending failure. For various reasons, the humans in the chain of events failed to act upon a potential problem (neglect), and it became an actual event at a later time.

Figure 1.1 Relationship of mechanical and human causes of aviation accidents.
Source: Chambers and Nagel 1985.

In 1963, Pearson recognized the importance of the role of human factors in airplane accidents. “The largest single cause to which light airplane accidents are attributed is pilot error which stems from inattention, poor judgment, distractions and fatigue. It is in this area where the greatest contribution can be made toward the reduction of accidents” (see p.).

The relationship of a human operator to a system or machine has been represented by this simple diagram (Figure 1.2) for many years. In the consideration of the human and machine as a system working together for the attainment of some common goal, the human is represented above the dotted line and the machine below it. The human component senses information from the machine’s displays and sometimes from the system’s response without it being represented upon a display. The human also senses information from the controls through which inputs are made to the machine and directly from the environment in which the system exists. These two components interact together within an environment that also affects the overall system’s performance. The environment includes the physical surroundings of the human–machine interface as well as the social and political climate that influences the human’s behavior with respect to his/her performance toward certain goals.

Figure 1.2 Human–machine relationship.
Source: Adapted from Birmingham and Taylor 1954.

Research has indicated that all the data that the human senses pick up do not get into the short-term memory (STM). I often tell my students that until I mention it, you are not aware that your shoes are full of feet. They wiggle their toes and begin to smile, and I know they got the point. Their senses were picking up the information, but it was not being registered in their short-term memory. They were not attending to those sensory inputs.

Another example is that if you close your eyes for a few moments (don’t go to sleep), keeping your eyes closed, face another direction and then very briefly open and close your eyes. For the brief moment that the eyes are open, virtually everything in the visual field is registered on the retina of the eye. Then, after the eyes are closed much of the image begins to fade away leaving you with the recollection of only a limited number of details. All of the visual information was there, even for a very brief period of time, but your attention captured only a few pieces of the information.

More elaborate studies have demonstrated that a cue following the very brief presentation of a multitude of information can improve the probability of recall of that information which occurred in the visual location of the post-stimulation cue.

There are various theoretical models of what information is attended to and how the information is processed, before the human makes a response. Simplistically, one might simply say that the information is processed and decisions are made. We do realize that the processing of the information is limited by the capacity of the STM of the human, and the information is also related to some of what the human has stored in long-term memory (LTM).

However, it appears that the individual, sensing information from the displays, the controls, and the environment relates that with what has recently occurred (STM) and what has happened in the past under similar circumstances (LTM). How did you respond in the past under the same situation, under similar circumstances, or if totally unique, what have you learned from the past (LTM) that might help in this situation? Are there various principles that you’ve learned in the past that might relate to how you should respond in this situation? In addition to drawing on the mere responses of the past, one also considers the results of the past responses (rewards and punishments). The decision-making process also draws on the history of the outcomes of past responses under similar circumstances, and the costs and benefits of various responses or not responding in the present situation.

Humans are not purely objective decision-makers. Most all of the decisions are tainted to some degree by our subjective assessment of the situation and the existing emotional state at the time. Humans are much more subjective or emotional decision-makers than purely objective decision-makers.

Human decisions, especially under time pressure (during flight), are seldom optimized. The typical human decision-maker selects the quickest course of action that will provide a satisfactory result. We call this “satisficing.”

Humans don’t always respond to situations by themselves but are influenced by the attitudes and behaviors of others within their environment, physically and socially. A strong influence upon an individual’s response is the expected acceptance of family, friends, supervisors, and others who observe the behavior.

Old saying: The true character of a person is what he would do if no one else were around to know what he did.

In aviation, the organizational politics, published regulations, and many, many unwritten rules guide and influence our behaviors and responses to virtually everything we do.

The commercial air carrier pilot is supposed to work with his/her fellow crew members as a small team with common goals under the restrictions of the published regulations, the unwritten rules of organizational behavior, to satisfy the desired outcomes of the multitude of passengers on board! The situation can become much more complex than the simplified schematic of the human–machine interface shown in Figure 1.2.

Another approach to explaining human factors is the SHEL model put forward by Edwards (1988) (Figure 1.3). It takes a systems approach to human factors in that there is the Hardware – the physical properties with which people work and interact, the Software – rules procedures, regulations, habits and customs, and the Liveware – the human beings, that all interact in and with an Environment.

Figure 1.3 The SHEL model.

Edwards (1988) offers the following definition of human factors:

Human factors (or ergonomics) may be defined as the technology concerned to optimize the relationships between people and their activities by the systematic application of the human sciences, integrated within the framework of system engineering.

Essentially, human factors is the study of the liveware (L) with a focus upon the design and optimization of the interfaces of L with the other components of the model (L–S, L–H, L–E), and L with other humans (L–L).

The person, Liveware, has knowledge of the rules, regulations, procedures and customs related to responding in specified situations. These are the things that he/she has learned. The individual also has certain habits of responding in certain ways to particular situations. These all form part of what is known as the interface between the liveware and software (L–S).

The engineers design the machines, the controls and displays, and the associated support equipment which the liveware utilizes. The relationship between the liveware and the equipment is called the liveware – hardware interface (L–H). This area was the principal focus of the early human factors engineers. In recent years, there has been great interest in the interaction between the liveware and the computer software that is a form of designed interface between the operator and the machine. This interface is also represented by L–H in the SHEL model.

The L–E interaction is recognized by all. The extremes of temperature, humidity and altitude are the most common environmental factors that may influence the pilot‘s performance. Sometimes the liveware tends to fool himself into thinking that the environment will not have an effect or that it will be only for a brief period of time that can be easily endured without any adverse effects. This L–E interface had long been the focus of study of aviation physiologists for the adverse effects upon the human body. The human factors researchers are more interested in the effects of the environment upon the cognitive functioning of the human operator, particularly perception, judgement and decision-making.

The environment also interacts with and has direct effects upon the hardware and its performance. As the environment affects the performance of the hardware, the software is modified to account for the effects of the environment.

In addition to all of these interfaces, there is also an interaction of the liveware with other liveware (L–L), as in team performance, crew behaviors, and instructor–student relationships. These L–L relationships have come under greater scrutiny following several notable commercial airline accidents, which were attributable to breakdowns in good L–L interfaces.

In a depiction more easily recognized by pilots, Roscoe, in his book on Aviation Psychology (1980), offers the following schematic of the functional relationship between a pilot and the airplane that he/she controls:

Figure 1.4 Functional model of pilot–airplane system operations. Source: Roscoe 1974; US Air Force technical report.

In Roscoe’s representation, the pilot is “sensing” directly from the environment as well as the airplane’s displays, and the pilot responds by “manipulating” the controls. The system (airplane) responds to the pilot’s manipulations through the actuation of the vehicle and engine controls.

In a 1997 publication of the Civil Aeromedical Institute of the Federal Aviation Administration (CAMI), Introduction to Human Factors in Aviation: A Tri-National Initiative, the human element is represented in a more systems perspective as being affected by four different external pressures:

• the machine
• the mission
• the environment and
• management, which includes culture, policies, and practices.

These models of human–machine–environment interactions are just simply models. They are the representations of how certain persons conceive reality and are not necessarily flawless or all encompassing.

Regardless of one’s preference for representing the role of the human factors, the facts are that at least 80 percent of the aircraft accidents and incidents are attributable, in some way, to human factors problems, especially if you include neglect of mechanical problems. That is, what the person does, or does not do, both outside and within the airplane cockpit in this chain of events may have caused or could have prevented the accidents or incidents.

How those individuals responded to the situations they faced often reflected their habits that were developed in prior training. These habits might have been or should have been noted in the evaluative process for the certification of the individual for his or her pilot ratings and in the periodic re-evaluation of the pilot’s knowledge, skills, and behaviors.

Yet, it is remarkable that the proportion of instructional material in civilian and military flight training does not reflect the contribution of areas that are involved ...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Illustrations
• Foreword
• Acknowledgments
• Part I Human factors
• Part II Applications and hints from the years
• References