The development of usability scales for flight management systems (volumes one and two)
Lane, Karen P.
Usability is a multidimensional concept, and although a number of techniques have been
developed for assessing usability, none have been developed specifically for the civil
flight deck or its components. The requirement for Human Factors tools to support civil
flight deck certification have been well documented (e.g. FAA, 1996). This thesis
reports on a research programme that resulted in the development of a series of scales to
assess the usability of Flight Management System (FMS) Control and Display Units
(CDUs). Since the goal of this research was to produce scales that could be used by
certification authorities and FMS manufacturers, demonstrating that the scales had
appropriate psychometric properties was critical. A rigorous and systematic approach to
the construction of the usability scales was therefore adopted.
The research was conducted in three studies. The first study involved the development
of a 49-item questionnaire that was distributed to airline pilots. A series of analyses on
the data collected demonstrated that a reliable and valid usability factor structure was
produced. The second study focused on the production of usability scales and examined
the impact of flight phase on usability ratings. Analyses demonstrated that the factor
structure produced in the first study was reliable, and was valid for data collected for the
cruise and descent and approach phases of flight. A series of internally consistent
usability scales was therefore produced which demonstrated evidence of discriminant,
face, content, and construct validity.
The third study involved a content analysis on a large volume of participant comments
derived during studies one and two, and examined the usability problems associated
with current FMSs and suggested improvements for future FMSs. The content analysis
produced evidence of construct validity for the usability scales developed, and permitted
recommendations for FMS designers and certification authorities to be made.
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