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Purpose of the experiment was to demonstrate the use of distraction stress to improve the validity of performance as a workload criterion.
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In a DC-7 flight simulator instrument approaches with and without flight director system were compared.
The superiority of the flight director system can be taken for granted and it could therefore be used as a criterion: flying performance should be better with flight director and this would be more obvious under distraction stress.
Material and methods.
Distraction stress. The BCG was used in a aural mode, paced condition (30 tones/min).
Subject had to respond by pressing push buttons on the left topside of the control column.
When an error or omission was made, a light on the dash-panel would illuminate.
Only one error per minute was allowed. If more errors were made, subject had to overshoot.
The flight performance criterion was obtained by averaging the total variance of speed and optimal horizontal and vertical approach path together.
This results in one figure for each condition. The larger the figure the poorer the flying performance.
Subjects were 3 junior airline pilots. Each made 8 approaches, equally divided over two sessions.
Figure 1 shows flying performance with and without distraction stress under the two conditions as described.
It is shown that distraction stress causes a deterioration in performance both for flight with and without flight director.
However for flights without the flight director the situation is much more pronounced.
Without flight director the flight performance error value increases by 97% under distraction stress.
With flight director this error value increases only by 36.5%.
Also, performance without distraction stress is slightly better without flight director.
Only with distraction stress the flight director proved to be superior.
Since this is already known, this finding illustrates the significance of the method.
Thus both findings support the hypothesis that under distraction stress the superiority of the more advanced system, as apparent from flying performance, is more obvious.
= Distraction stress
FD = With flight director
NFD = Without flight director
Validation of constructs II "Main Page"
Copyright J. P. Krol ©