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Software Considerations in Airborne Systems

Software Considerations in Airborne Systems. Koray İnçki Spring 2009. Safety-critical?. Safety: Safety is a property of a system that it will not endanger human life or the environment. Safety-Critical System:

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Software Considerations in Airborne Systems

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  1. Software Considerations in Airborne Systems Koray İnçki Spring 2009

  2. Safety-critical? • Safety: Safety is a property of a system that it will not endanger human life or the environment. • Safety-Critical System: A system that is intended to achieve, on its own, the necessary level of safety integrity for the implementation of the required safety functions. Koray İNÇKİ, CmpE Spring 2009

  3. What is DO-178B? • Overview • RTCA • Software use in Airborne Systems • Not a “Process” document; instead a discussion of the certification process and relationship to system and software lifecycle for commercial avionics • A guideline of best practices for safety critical software development on airborne systems Koray İNÇKİ, CmpE Spring 2009

  4. DO-178B Overview • In 1985, revisions and updates were made to produce DO-178A / ED-12A. • The documents became a worldwide basis for software certification in the aviation industry • Three basic Software Lifecycle Processes • Software Planning Process • Software Development Process • Correctness, Confidence & Control Process Koray İNÇKİ, CmpE Spring 2009

  5. Guidelines • The guidelines in DO-178B impose constraints on the software development process so that the resulting system is safe. • The FAA’s DO-178B offers guidelines for the development of airborne systems equipment software. • Most RTOS tool vendors have accepted the guidelines in DO-178B and begun to offer tool support. Koray İNÇKİ, CmpE Spring 2009

  6. What are we dealing with? Koray İNÇKİ, CmpE Spring 2009

  7. DO-178B Document Layout Koray İNÇKİ, CmpE Spring 2009

  8. DO-178B Software Levels Koray İNÇKİ, CmpE Spring 2009

  9. DO-178B Processes and Outputs • DO-178B is divided into six main processes: • Software Planning Processes • Software Development Processes • Software Verification Processes • Software Configuration Management Processes • Software Quality Assurance Processes • Certification Liaison Processes • Each process has a set of expected documented outputs. Koray İNÇKİ, CmpE Spring 2009

  10. Software Planning Process • Activities addressing system requirements and certification levels • Inter-relationships between processes, sequencing, feedback, and transition criteria • Lifecycle environment, including methods and tools • Software development standards • Software plans that comply with DO178B • Coordination of development and revisions to plans Koray İNÇKİ, CmpE Spring 2009

  11. Software Planning Process Outputs • Plan for software aspects of certification (PSAC) • Software development plan (SDP) • Software verification plan (SVP) • Software configuration management plan (SCMP) • Software quality assurance plan (SQAP) • System requirements • Software requirements Specifications(SRS) • Software design standard (SDS) • Software code standard (SCS) Koray İNÇKİ, CmpE Spring 2009

  12. Software Development Process • The software development process is broken into four sub-processes: • Software Requirements Process • High-level requirements in relation to function, performance, interface and safety. • Software Design Process • Low-level requirements used to implement the source code. • Software Coding Process • Production of source-code from the design process. • Integration Process • Integration of code into a real-time environment. Koray İNÇKİ, CmpE Spring 2009

  13. Software Development Process Outputs • The following tangible outputs are the result of the combined four sub-processes: • Software requirements data (SRD) • Software design description (SDD) • Source code • Executable object code Koray İNÇKİ, CmpE Spring 2009

  14. Software Verification Process • The purpose is to identify and report any errors resulting from the development process. • The verification process objectives can be met with reviews, walkthroughs, unit testing, integration testing, and more. • Proof of objectives is within the execution of the testing procedures. • Outputs include: • Software verification cases and procedures (SVCP) • Software verification results (SVR): • Review of all requirements, design and code • Testing of executable object code • Code coverage analysis Koray İNÇKİ, CmpE Spring 2009

  15. Software Verification Process.. Koray İNÇKİ, CmpE Spring 2009

  16. Software Configuration Management Process • The purpose is to establish secure and effective configuration control for all artifacts. • The following activities are done within the process: • Configuration Identification • Change Control • Baseline establishment • Archiving of the software • Outputs include: • Software configuration index (SCI) • Software life cycle environment configuration index (SECI) Koray İNÇKİ, CmpE Spring 2009

  17. Software Quality Assurance Process • The purpose is to provide assurance that the software life cycle process is going to yield quality software. • Each process is analyzed to show that each process is producing the expected outputs. • Any changes from originally proposed plans are reported, evaluated, and resolved to ensure process integrity. Koray İNÇKİ, CmpE Spring 2009

  18. Software Quality Assurance Process • Outputs: • Software quality assurance records (SQAR) • Software conformity review (SCR) • Software accomplishment summary (SAS) Koray İNÇKİ, CmpE Spring 2009

  19. DO-178B Certification • Typically a Designated Engineering Representative (DER) working for e.g. FAA in an airplane manufacturing company. • D0-178B very specifically addresses the following which directly affects product development. • Certification of a product applies only to it's finished result. • Certification includes approval of all systems and subsystems, hardware, software, firmware, development tools, production, and testing of the product. • Certification is done on the individual application of the product • Coding practices must be certified to ensure things like "dead code" are not allowed. • Certification requires that 'full testing' of the system and all of it's components (including firmware) be done on the target platform in the target environment. • Certification requires code testing at the MCDC level. Koray İNÇKİ, CmpE Spring 2009

  20. A RTOS Perspective of DO-178B Koray İNÇKİ, CmpE Spring 2009

  21. Development Tools Koray İNÇKİ, CmpE Spring 2009

  22. References • “DO-178B, Software Considerations in Airborne Systems and Equipment Certification.” Wikipedia The Free Encyclopedia. 13.May.2009. Wikimedia Foundation, Inc. June 2003. http://en.wikipedia.org/wiki/DO178B • Johnson, Leslie A. (Schad). DO-178B, “Software Considerations in Airborne Systems and Equipment Certification.” Flight Systems. 4 March 2007. Boeing Commercial Airplane Group. 4 March 2007. http://www.stsc.hill.af.mil/crosstalk/1998/10/schad.asp • RTCA/DO-178B, "Software Considerations in Airborne Systems and Equipment Certification," December 1, 1992 • http://www.highrely.com Koray İNÇKİ, CmpE Spring 2009

  23. Have a safe flight! Koray İNÇKİ, CmpE Spring 2009

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