Introduction to Human Factors in Aviation

AVIA 4000, Special Projects: Human Factors in Aviation

Raymond E. Cain, Jr., Ph.D., Instructor

Lesson Objectives

After completing this unit of instruction, the student will be able to demonstrate the following:

Define the term human factors Describe the types of problems that human factors attempts to solve Translate the history, evolution, and development of human factors into

novel solutions Explain the utility of viewing human factors from the SHEL(L) perspective List the components of the SHEL(L) model Describe the major characteristics of each SHEL(L) model component Explain the interaction of liveware to itself and to the other components

of the SHEL(L) model Apply the SHEL(L) model to complex human factor problems

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What is Human Factors?

Generally speaking, human factors is the study of the interaction between humans and their environments. The operative work here is interaction and it suggests the dynamism that encompasses mans relationship with the things of creation and the things he creates. Itthat is to say human factors and its associated interactionsalso, nonetheless, describes the boundaries or interfaces at which things may go terribly awry. So, it is also a study of fit between the human, its creations, and its environment.

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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

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Debunking the definition

Human factors and ergonomics are used synonymously; however, ergonomics is usually associated with design

Human factors is problem oriented rather than discipline centered

Human factors involves people and their activities Human sciences comprise all those studies of the structure and

nature or human beings, their capabilities and limitations, and their behavior both singly and in groups

Ergonomists integrate their contributions with those of other people

The optimization of relationships comprises two sets of criteria: human wellbeing and the effectiveness of system performance

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Evolution of Human Factors

18801890 Taylors and Gilbreths time in motion studies

19241930 Western Electrics Hawthorne Effect 19401945 The Cambridge Cockpit (Design/layout

in a simulator) 1950the Ergonomics Research Society (United

Kingdom) The word ergonomics was coined by Professor K.F.H.

Murrell and means the science of work

1957Human Factors Society (United States) 1961International Ergonomics Association

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Emergence of Aviation Human Factors

1971 Human Factors in Transport Aircraft Operations Started at Longhborough University in England

197520th Technical Conference of IATA Something amiss related to the role and performance of man in

civil aviation HF educational gap existed in aviation transportation

1976ASRS set up in the US 1977Tenerife 1978KLM provided the first human factors awareness

program 1982CHIRP set up in the UK

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Examples of Human Factors Problems

Human behavior and performance Cognitive processes (e.g., situation awareness,

decisionmaking, judgment, etc.) Design

Hardware Controls and displays Flight decks, aircraft cabins, public facilities

Software

Communications Human resource selection and training

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The integration model: SHEL

Softwarerules, regulations, laws, orders, standard operating procedures, customs, practices, and habits which govern the manner in which the system operates and in which the information in it is organized

Hardware (physical property)buildings, vehicles, equipment, materials, etc.

Environment

Livewarehuman beings

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The SHEL(L) Model

The SHEL Model was originally conceived by Elwyn Edwards in 1972

Edwards conceptualized human factors as the interface between humans (Liveware) and the Software and tools (Hardware) they use within an Environment (p. 3).

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The Original SHEL Concept

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The SHEL ModelInterrelationships

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The SHEL Modelillustrating the interrelationships

between the three types of system

resources and their environment

L

H S

E

1. The lines joining the system

components represent the

interfaces through which

energy and information are

interchanged

2. It is at these boundaries

that many of the systems

problems occur under

operational conditions

3. It is certainly true that

mismatches at the interfaces,

rather than catastrophic failures

of single components, typify

aviation disasters

Hawkins SHEL Adaptation The SHEL model was modified into a building block concept in 1984 by Frank H. Hawkins

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Assumptions of the SHEL model

No arrangement of hardware, software, and liveware exists in vacuo

These resources operate in the context of an environment made up of physical, economic, political, and social factors The environment consists of those factors or

elements that are NOT in the control of system designers

Further, this is simply a convention to distinguish our system from the rest of the universe

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Livewarequintessentially it!

Liveware (or the human) is the most important component of the SHEL model

The study of liveware interactions between and among other SHEL components requires a multi and interdisciplinary approach, for example . . . Medicine Physiology Psychology Ergonomics

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The SHEL model: LH Interface

Knowledge of both component types is necessary

The ergonomist provides expertise concerning the liveware component

The systems engineer provides expertise concerning the hardware component

However, each system component may, to some extent, be tailored to suit the characteristics of the other

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The SHEL model: LH Interface

Liveware CANNOT be fundamentally redesigned Its properties are variable only within relatively narrow limits

Other system resources may be contrived to fulfill their roles Design decisions are bounded only by the laws of nature,

constraints imposed by the environment, and by the limit of the designers ingenuity

System design must first accept liveware characteristics followed by the design of other resources to match these human properties, which must be accepted as a given This approach is frequently inhibited by an inherent human

tendency to design for individuals as they should be, or as they are mistakenly believed to be

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The SHEL model: LS Interface

The pilot must conform to several sets of rules, regulations, conventions, and operating procedures

Software must not be in conflict with human characteristics It is futile to formulate rules that cannot be followed

Thus, during a violations investigation, were the rules, rather than the violators, at fault?

Since most rules and regulations are codified in paper form, these documents are hardware Therein lies another issue: the relative availability and

interpretability of these documents

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The SHEL model: LE Interface

Factors over which designers and operators have no control physical environment

temperature radiation air pressure weather

political and economic constraints deregulation oil prices supply and demand

changing circumstances

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Examples of SHEL interface errors

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Poor Equipment Design

Poor Procedures and Difficult Manuals

Poor Comfort Environment and Effects of Jet Lag

Poor Communication, Leadership, Followership, Teamwork, and DecisionMaking

Adding the Third Dimension

Systems typically comprise several units of each type of resource thus, more opportunity for failures

HH plug and socket design signal data formats impedance matching

SS operating procedures versus rules and regulations versus

aircraft certification

LL interrelations among crews, cabin staff, ATC, ground crews,

and other personnel

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ThreeDimensional SHEL Model

The threedimensional SHEL Model: additional dimensions have been added to the model to emphasize that systems typically comprise several units of each type of resource

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SHELCommand & Authority

Coordination of team (crew) efforts the crew commander must achieve satisfactory working

relationships neither an overbearing, dictatorial approach (command

role overemphasized) nor one in which the command function is obscured (command role underemphasized) will be satisfactory

TransCockpit Authority Gradient (TAG, Edwards, 1975) the variable to be optimized ensures a uniformly high standard of flight-deck

management and interpersonal relationships

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How should flight crews interact in the cockpit?

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What is the appropriate gradient for symbiosis?

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SHELSystem Stability

A welldesigned system exists in a state of equilibrium, which is dependent upon highly interactive links between its component parts

Any changeseven smallwithin a SHEL system may have far-reaching, undesirable, deleterious consequences

Even in the absence of modifications to resource components, continuous review of a dynamic system is necessary in order to adjust for changes beyond the control of the system designers and managers

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SHELSkill & Error To Err is Human!!

Humans have the capacity to acquire and employ skills

However, the notion of skill is inseparable from that of error

The philosophy of HF is to study the nature of error, and having done so, to take the necessary steps to control it, minimize it, mitigate it, and eliminate any deleterious effects of it

From this posture, it is known that errors can be classified into types having different etiologies and different treatments

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LCentered Approaches to Error

The most fruitful component to modify is L? Through training

Through education

However, there may be tradeoffs to consider between the choice of training (L), of equipment modification (H), or of procedural changes (S)

A second humancentered approach to error is to determine the point in the sequential chain of human information processing at which a breakdown occurred

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LCentered Approaches to Error

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LCentered Approaches to Error

When assessing human information processing error, the result of such an analysis should suggest ways in which the probability of error may be

diminished, and appropriate means of detection and correction

Management skills are equally susceptible to this approach Failures in communication Inadequacies in the form of leadership provided

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The Contemporary Scene

HF has the task of keeping abreast of new developments in hardware technology

Much of the current activity centers around the introduction of sophisticated automatic systems

Pilots tasks are now little concerned with the direct control of aircraft but with providing strategic decision making and supervisory management of the automatic systems

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Humans are well human!!

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