Ian sommerville 2004 slide 16 software engineering

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Unformatted text preview: sons learned Inquiry report makes detailed recommendations for future development of the LAS CAD system, including: Focus on repairing reputation of CAD within the service; Increasing sense of `ownership' for all stakeholders; They still believe that a technological solution is required; Development process must allow fully for consultation, quality assurance, testing, training; Management and staff must have total, demonstrable, confidence in the reliability of the system; Any new system should be introduced in a stepwise approach. Ian Sommerville 2004 Slide 17 Software Engineering Case Studies The Ariane 5 Launcher Failure June 4th 1996 Total failure of the Ariane 5 launcher on its maiden flight Ian Sommerville 2004 Slide 18 Software Engineering Case Studies Ariane 5 A European rocket designed to launch commercial payloads (e.g.communications satellites, etc.) into Earth orbit Successor to the successful Ariane 4 launchers Ariane 5 can carry a heavier payload than Ariane 4 Ian Sommerville 2004 Slide 19 Software Engineering Case Studies Launcher failure Approximately 37 seconds after a successful lift-off, the Ariane 5 launcher lost control. Incorrect control signals were sent to the engines and these swivelled so that unsustainable stresses were imposed on the rocket. It started to break up and was destroyed by ground controllers. The system failure was a direct result of a software failure. However, it was symptomatic of a more general systems validation failure. Ian Sommerville 2004 Slide 20 Software Engineering Case Studies The problem The attitude and trajectory of the rocket are measured by a computer-based inertial reference system. This transmits commands to the engines to maintain attitude and direction. The software failed and this system and the backup system shut down. Diagnostic commands were transmitted to the engines which interpreted them as real data and which swivelled to an extreme position resulting in unforeseen stresses on the rocket. Ian Sommerville 2004 Slide 21 Software Engineering Case Studies Software failure Software f...
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