ABSTRACT
The objective of the research was to develop and validate a multifaceted model such as a fuzzy analytical hierarchy process (AHP) model that considers both qualitative and quantitative elements with relative significance in assessing the likelihood of falls and aid in the design of Ground Support Operations in aerospace environments. The model represented linguistic variables that quantified significant risk factor levels. Multiple risk factors that contribute to falls in NASA Ground Support Operations are task related, human/personal, environmental, and organizational. The subject matter experts were asked to participate in a voting system involving a survey where they judge risk factors using the fundamental pairwise comparison scale. The results were analyzed and synthesized using Expert Choice Software, which produced the relative weights for the risk factors. The following arc relative weights for these risk factors: Task Related (0.314), Human/Personal (0.307), Environmental (0.248), and Organizational (0.130). The overall inconsistency ratio for all risk factors was 0.07, which indicates the model results were acceptable. The results show that task related risk factors are the highest cause for falls and the organizational risk are the lowest cause for falls in NASA Ground Support Operations. The rationale in this research is to justify using the priority vector to validate the weights by having two different sets of experts/decision makers create priority vectors separately and confirm the weights are similar. The fuzzy AHP model was validated by applying it to three scenarios in
NASA KSC Ground Support Operations regarding various case studies and historical data. The design of the experiment was a repeated measures analysis to evaluate three scenarios in NASAKSC Ground Support Operations. As a result, the predicted value was compared to the accepted value for each subject. The results from this model application confirmed that the predicted value and accepted value for the likelihood rating were similar. The three scenarios were Shuttle Landing Facility (SLF), Launch Complex Payloads (LCP), and Vehicle Assembly Building (VAB). The percentage error for the three scenarios was 0%, 33%, 0% respectively. The Kendall Coefficient of Concordance for assessment agreement between and within the subjects was significantly 1.00. Therefore, the appraisers are applying essentially the same standard when evaluating the scenarios. Multiple descriptive statistics for a 95%, confidence interval and t-test are the following: coefficient of variation (21.36), variance (0.251), mean (2.34), and standard deviation (0.501). The results indicate there is minimal variability with fuzzy AHP modeling. As result, model evaluation and validation indicates that there is no difference between the current accepted NASA model and developed fuzzy AHP model. Future research includes developing fall protection guidelines.
