Advanced Technology Aircraft Safety Survey Report - Australian ...

WORKLOAD
WORKLOAD
Introduction
The term ‘mental workload’ refers to the difference between the amount of information
processing resources required by a situation and the amount of such resources available to the
person at the time (Wickens 1992). The more that the demand approaches capacity, the
greater the workload. When the demand reaches a level such that the person’s performance is
significantly affected, then a person can be said to be ‘overloaded’.
A high workload level can have a variety of influences on human performance. The majority
of these effects can be considered as attempts by the person to reduce demands by simplifying
them. For example, a high workload can lead to a narrowing of the perceptual information a
person attends to and a narrowing of the number of tasks a person attempts to perform. A
person generally focuses on those information sources and tasks which he or she thinks to be
the highest priority. However, this prioritisation process is subjective and may not necessarily
be optimal. Working memory and decision making processes are also limited by high
workload. These limitations can exacerbate a variety of decision making biases, and lead to a
focus on certain aspects of tasks (e.g. speed) in opposition to others (e.g. accuracy).
If multiple tasks are being performed simultaneously, the performance of each of the tasks
often deteriorates to some extent. The amount of interference between tasks increases if the
same stages of information processing, input modalities, processing codes and types of
response are involved. Another commonly discussed means of reducing task demands
involves reverting to stereotyped patterns of behaviour. In addition, there is a tendency to
focus on simpler tasks and responses, which generally but not always are the more established
patterns of behaviour.
High workload can have negative influences on all aspects of human information processing.
It can also be associated with the physiological responses associated with an increased
perception of threat or stress. The maintenance of a high workload over a sustained period of
time can therefore be associated with a variety of other negative influences.
This chapter discusses the responses of pilots regarding their perception of the effect of
automation on workload. The questions in this section address periods of low workload,
emergency situations and total workload. Pilots were also asked to assess the effect of
automation on fatigue.
Workload and boredom
Thirty-six per cent of respondents considered that times of low workload in an automated
aircraft were boring (see fig. B6.1). This supports anecdotal evidence that suggests that
automation accentuates times of low workload. It also relates to question B9.4 where 32% of
respondents indicated that they had inadvertently fallen asleep on the flight deck of an
advanced technology aircraft.
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