Navigation path

Decrease textIncrease textDividerPrint versionRSSDivider

Improvement of Safety Activities on Aeronautical Complex Systems


Avionic systems are becoming increasingly complex (heterogeneous components, large number of functions, and interaction with operators through advanced interfaces). Therefore, it is becoming harder to manage all aspects of safety assessment and to maintain the required safety levels. A Fifth Framework Programme project called ESACS (Enhanced Safety Assessment for Complex Systems) has shown the benefit of using formal techniques to assess aircraft safety. ISAAC builds upon and extends the ESACS results to go a step further towards the improvement and integration of safety activities of aeronautical complex systems.

Project objectives

The ISAAC project aims to increase the capability and efficiency of safety and systems engineers to perform safety assessments resulting in secure systems. The proposed methodology, built on formal method techniques, is an integrated part of a model-based development process where safety and reliability aspects are examined in the early steps of development.

The goals of the project are:

  • to consolidate the ESACS results by improving analysis for dynamic aspects like sequencing or temporal behaviour
  • to extend the scope of the integrated environment among designers and safety/reliability engineers
  • to take into account results from tools used in performing particular risk and zonal safety analysis and to use this information to analyse unintended interactions injected into independent ‘intended functionality’ but co-located systems
  • to evaluate the relationship between man and machine offering a complex human-complex machine interaction model
  • to automate the analyses to determine the impact of degraded situations on system operating modes and over pre-defined missions
  • to exploit the use of ESACS formal verification techniques to deal with testability aspects.

Description of the work

To reach the above goals, the ISAAC work will follow detailed technical and scientific objectives organised into three complementary dimensions, which are structured into basic topics.

First dimension: Consolidation of ESACS work

Integration with higher-level notations for requirements, extension of traditional techniques to timing aspects and quantitative analysis, further development of platform/tools already started in ESACS.

Second dimension: Extension to other safety related aspects

Human errors, common cause analysis, mission analysis and testability.

Third dimension: Commonalities

Common methodology recommendations and common tools and libraries that facilitate exchanges among tools will be identified in order to provide a more comprehensive tool-supported coverage of the safety process.

Expected results

A comprehensive methodology of different safety-related aspects, supported by tools that allow the various analyses. The main benefit is that activities of designing and doing analysis can be performed more easily in an iterative manner resulting in a more effective development process, where the results of the analysis can influence the design in a short period of time. Moreover, the traceability of safety issues and of relevant design changes will be improved, enhancing the visibility in the perspective of the certification process.