By the same authors

Safety Critical Software

Research output: Chapter in Book/Report/Conference proceedingEntry for encyclopedia/dictionary



Publication details

Title of host publicationEncyclopedia of Aerospace Engineering
DatePublished - 2012
PublisherJohn Wiley & Sons
EditorsRichard Blockley, Wei Shyy
Original languageEnglish
ISBN (Electronic)9780470686652


Safety is concerned with control of hazards, that is, situations that could lead to a loss of an aircraft, or other types of harm. Software is of relevance to the safety of aircraft where it has a potential role in contributing to hazards, or in controlling them. It is shown that a crucial issue underlying all of the process is that software can be a contributory cause to unsafe behavior when its “model” of the state of the world diverges sufficiently from reality, for example, not determining that an aircraft has landed, and thus inhibiting braking functions.

This chapter identified ways in which system safety processes can be extended into software to treat software issues in as integral a manner with the rest of the design process, as is possible. For example, it discussed how classical safety analysis techniques can be adapted for software. The chapter also addresses the particular challenges of software, particularly that the possibility of causing hazards arises only from systematic causes, for example, design defects, not from physical failure causes. It explains what can be done to help reduce the incidence of such problems, and how evidence can be presented to enable informed decisions to be made about the suitability of software for safe operational use.

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