The
Emergence of Human Factors
by
Professor Helen Muir © 2009
Professor Helen Muir is Professor
of Aerospace Psychology and Head of Human Factors Group at Cranfield
University College of Aeronautics. ”Human Factors” is a topic central to
flight safety but, in my opinion, is more often talked about than understood.
This article gives a clear and concise introduction to the increasing
awareness of the role played by human factors in aircraft accidents.
Awareness of the crucial influence human factors have on accident rates is
probably lower among General Aviation pilots (and instructors) than in any
other sector of aviation. An understanding and constant awareness of the
important relationship between human factors and safety will help to reduce
accident rates.
We thank Professor Muir for a thought-provoking conversation about human
factors and for her kind permission to publish this article on Gremline.
For centuries before the first flight of Orville
and Wilbur Wright, humans had engaged both their imagination and ingenuity in
an attempt to emulate bird flight. This early achievement began an
evolutionary programme which has led to supersonic civil transport, to
spaceflight and to outstanding military capabilities. In fact, it is
difficult to imagine a more impressive tribute to applied physical sciences
than the recognition of the achievements in aeronautics and
astronautics.
To recognise the aerospace achievements in solely engineering terms
would be to ignore an important element. The fact that aircraft are
controlled by people who, together with the many ground support personnel
essential to their safe and effective operations, had led to a need to
understand the human role in aircraft operations. This in turn had led to the
involvement of the applied human sciences in aerospace. As a consequence we
are now fully aware of the fact that flight crews and other operational
personnel must be selected and trained according to clearly defined criteria
and that equipment must be designed to ensure that the task demands will not
exceed the capabilities of human performance.
The
emergence of the discipline of human factors has been relatively recent,
although its origins can be traced back over sixty years. The Second World
War provided a huge impetus to the development of aviation and, as part of
this, evidence of the human problems became apparent. As early as 1940, the
‘70% human error’ in aircraft accidents findings has been published. The fact
that the performance of combat aircraft and the success of missions depended
on the skill of the crews performing in extremely hostile environments led to
the realisation that our understanding of the acquisition and maintenance of
skills was severely limited. This subsequently led to the initiation of new
research programmes.
In 1939, the Head of the Psychological Laboratory at Cambridge
University, Sir Frederick Bartlett, was commissioned by the Medical Research
Council to undertake research into the problems associated with military
aviation. The team which he developed was to dominate academic psychology in
the United Kingdom for the next generations and its research into the
fundamental nature of human skills led to contributions in the area of
aircrew selection and training, the effects of sleep loss and fatigue, and
aspects of visual perception and display design. The ‘Cambridge Cockpit’
developed largely by K.J.W. Clark was used for these studies. This was a
piece of experimental equipment built around a Spitfire cockpit into which
was fitted a panel with instruments which responded in a realistic manner to
movements of the controls. Using this equipment, the experimental
psychologists demonstrated that when fatigued, the degradation in pilot
performance led to peripheral activities such as checking fuel being
overlooked with attention being paid only to one or two instruments, the
others being ignored. (Reference 1)
In America, research into the design of displays and instruments also
began to be undertaken. In 1947, Fitt and Jones (Reference 2) identified nine
sources of errors made in the interpretation of instruments including
misinterpretation of information, legibility problems, scale of
interpretation errors and illusions.
The late
40s and 50s saw the publication of numerous papers in the field of skill
acquisition and control performance, much of which is based on research into
the flying task. For example, in 1947 Williams (Reference 3) suggested that
the pilot’s task could be analysed into four sub-goals described as
directional, attitudinal, temporal and mechanical.
Investigations by Mackworth (Reference 4) into the performance of radar
operators made a major contribution to the understanding of our ability to monitor
situations. In the UK, the 50s saw the establishment of ergonomics as a
discipline, whereas in the USA the term ‘human factors’ was introduced. These
words are usually regarded as synonymous.
The late 50s and early 60s will be remembered for important
developments in our understanding of perception and communication, notably by
Broadbent (Reference 5) who was by then leading the team at Cambridge. This
work has formed the basis of what has become known as Cognitive Psychology.
This involves our understanding of how we take in information from the world
around us and process it in such a way that we make a decision to take some
action or store information in our memory systems. During this period, our
knowledge and understanding of the influence of stress on performance and the
influence of different types of stress, e.g. environmental, work, domestic
etc., was substantially increased (Reference 6). Our knowledge of all these
processes is obviously fundamental to understanding human performance of the
flying task since it enables us, for example, to identify types of error and
their associated causes as seen in the table at the end of this
article.
The 1970s saw the application of much of this work to the flight
deck. Studies of pilot workload were introduced in order to ensure that the
workload associated with flying the aircraft did not at any time exceed the
capabilities of the required crew at any period of the flight. These
techniques became part of the certification process. Indeed, workload
assessment techniques were later used for the determination of whether a
civil cockpit should be crewed by two or three pilots.
The 1970s also saw the first attempt by aviation psychologists to
conceptualise the relationship between the human and the rest of the aircraft
system. In 1972, the SHEL model was published by Edwards (Reference 7) in
which the interaction between the Hardware, I.e. the aircraft, the Software,
in other words the operational procedures, rules, etc., the Lifeware
involving the flight crew and the Environment e.g., the physical, economic
and social factors, was described.
Since the
early 70s, one of the principal topics under consideration has been the
development of flight deck automation. Over the last 15 to 20 years there has
been a rapid evolution of display and control devices including the
introduction of electronic computing devices which provide a range of support
facilities for aircraft guidance and control. In the early stages of
automation, the systems were developed by engineers and human factor
specialists were not involved until the system had been installed in the
cockpit and required evaluation. The increasing awareness of human factors
has led to the situation where the major manufacturers now involve human
factor expertise at all stages of the design process. The recognition that
flying a modern aircraft is no longer a one man effort but rather a team
managing a system has led to the acceptance of the importance of human
factors training and indeed crew resource management for all pilots
(reference 10). In the space of sixty years, human factors has not only
emerged as a discipline but has been recognised as being of such importance
within the aviation community that in the UK human factors is part of the
licensing requirement for all new pilots. In addition, crew resource
management training is mandatory for all commercial pilots and part of
recurrent training. The lead shown by pilots to recognise the value of human
factor training will, it is hoped, be followed by other personnel in the
industry responsible for safety. The complete elimination of human errors may
be an unrealistic goal but advances to minimise the causes and consequences
of error in aviation is one to which all human factors specialists are
dedicated.
