System Safety and Reliability Analysis


In aerospace, safety means that the risk of a serious accident is lower than a respective boundary risk stipulated by certification regulations. Reliability denotes the likelihood of an aircraft to be dispatched for flight on time due to the absence of technical problems.
Safety and reliability have to be dealt with as an integral part in the development process of an aircraft and its systems.
Stand-alone, manual tools (not coupled with physical modelling and simulation) for safety and reliability analysis are typically used in aerospace.
Due to the effort involved, safety and reliability analyses are usually conducted only twice in the development process. This increases the risk of detecting design problems late in the process.


Methods and tools founded on object-oriented, physical modelling are developed by the team Energy Systems for design and dimensioning of aircraft systems, such as environmental control, electric generation and distribution, or flight control actuation. Fault modelling is introduced to simulate normal or degraded operating states of system architectures. This allows to analyse and minimise the loads, and in turn the sizes and weight of the components of a system.
Fault modelling and simulation forms a basis also for safety and reliability analysis methods developed by the team Energy Systems. In essence, the methods are an automated detection of minimal path sets or minimal cut sets.
Integration of automated safety and reliability analysis methods with system architecture design tools supports an early and continued use of them in the design process. Problems are detected early, which ensures that a system design fulfills the mandated levels of safety and reliability.

Selected Publications

  • Schallert, C.: Inclusion of Reliability and Safety Analysis Methods in Modelica. 8th international Modelica conference, 20. – 22.03.11, Dresden.
  • Schallert, C.: Incorporation of Reliability Analysis Methods with Modelica. 6th International Modelica conference, 03. - 04.03.08, Bielefeld.

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