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Improving Airplane Safety by Incorporating Diagnosis into Existing Safety Practice

Safety has always been at premium in airfare. There is a long history of systematic work in the field, and current practice has established a high degree of safety that has resulted in so low failure numbers that the public finds confidence in the process of air worthiness certification. However, the design and development process of airplanes to achieve this is costly and may be even more so since modern airplanes become more and more complex. Furthermore, recent trends towards \emph{Unmanned Aerial Vehicles} (UAV) are likely to require even more efforts and costs, to fulfill the increased safety requirements. Therefore it is interesting to investigate modern techniques that promises to improve safety at reduced costs. One such technique is diagnosis. Diagnosis in general is a term that includes several research and application fields. Examples of such fields, that are technology drivers, are the fields of supervision both on-line (on-board) and off-line (on ground), operator support that evolved from the Harrisburg accident, and law based emission diagnostics regulation e.g.\ as stipulated by \emph{California Air Resource Board} (CARB).

The current work is an investigation in the cross field between safety assessment and diagnosis techniques. The first step was to root the work in existing safety practice. This means that the Swedish defense procedure has been adopted as described in \emph{H SystSäk E}. It is a safety framework that uses fault tree analysis and failure mode effect analysis as important tools. Thereafter some flight applications were investigated together with Saab specialists to capture and formulate some aspects that are non-trivial to cast in the existing safety framework. Examples of such aspects found are for instance related to performance requirements in different operational model. A principle case study was then formulated using laboratory equipment, with the aim to capture some of the identified aspects in the problem formulation. A complete process for safety analysis was then completed along the lines of \emph{H SystSäk E} including all meetings and documents required therein. Several observations were done during this work, but the overall conclusion so far is that the effect of introducing diagnosis algorithms can be handled in the safety analysis, and, yes, that there is a promise that diagnosis algorithms can improve safety in a structured quantitative way by lowering the contribution to the total failure risk from the subsystem being diagnosed.

Jonas Biteus, Gunnar Cedersund, Erik Frisk, Mattias Krysander and Lars Nielsen


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Senast uppdaterad: 2021-11-10