An Exploration of Function Analysis and Function Allocation in the Commercial Flight Domain
DOUGLAS AIRCRAFT CO LONG BEACH CA
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Two approaches to function analysis and to function allocation were investigated. One function analysis approach Bottom-Up extracted functions from a very detailed task time line TTL database. These were the functions that might have been implemented to produce the task performance documented in the TTL. A second approach Top-Down created a functional architecture of the objective Accomplish Commercial Transport Missions using the function modeling method Structured Analysis and Design Technique SADT. Comparable functions were found for both methods in the Lift-Off segment, at the lowest level of decomposition. In the Bottom-Up approach, although the analysts attempted to eliminate references to any specific design implementation, its content might be influenced by the existing allocations. The Top-Down model made no assumptions about automation. The Bottom-Up approach was valuable in relating functions to the time interval of the mission during which they occurred. It also provided the capability for relating the Top-Down model which does not address time or sequence to the mission time line. Both methods are valuable. A detailed treatment of each model is given in the Appendices. The first approach to function allocation, Method A, is a comprehensive, iterative process that is integrated with the system engineering effort. It emphasizes the iteration of the three steps of allocation, design and evaluation. This method explicitly incorporates a human-centered approach to allocation, viewing the human operator as a multidimensional resource whose cognitive and performance characteristics must directly influence the allocation process. This method also encourages the development of adaptive allocation schemes capable of making on-line decisions responsive to situation-specific changes on the flight deck. The second approach, Method B, is a relatively brief, simplified system designed to provide an effective first cut allocation.
- Civilian Aircraft
- Numerical Mathematics