Therac-25 : Summary Malfunction Complacency Race condition (turntable / energy mismatch) Data overflow (turntable not positioned) time‘85‘86‘88 ‘87 Micro-switch.

Slides:

Advertisements

Similar presentations

Testing Workflow Purpose

Advertisements

Test process essentials Riitta Viitamäki,

CSCI 5230: Project Management Software Reuse Disasters: Therac-25 and Ariane 5 Flight 501 David Sumpter 12/4/2001.

“An Investigation of the Therac-25 Accidents” by Nancy G. Leveson and Clark S. Turner Catherine Schell CSC 508 October 13, 2004.

The Therac-25: A Software Fatal Failure

Software Quality Assurance Plan

Software Engineering CSE470: Process 15 Software Engineering Phases Definition: What? Development: How? Maintenance: Managing change Umbrella Activities:

Social Implications of a Computerized Society Computer Errors Instructor: Oliver Schulte Simon Fraser University.

An Investigation of the Therac-25 Accidents Nancy G. Leveson Clark S. Turner IEEE, 1993 Presented by Jack Kustanowitz April 26, 2005 University of Maryland.

Therac-25 Lawsuit for Victims Against the AECL

PERTEMUAN - 2 SOFTWARE QUALITY. OBJECTIVES After completing this chapter, you will be able to: ■ Define software, software quality and software quality.

Therac-24 The Upshot. Summary/Overview Six patients received radiation overdoses during cancer treatment by a faulty medical linear accelerator, the Therac-25.

+ THE THERAC-25 - A SOFTWARE FATAL FAILURE Kpea, Aagbara Saturday SYSM 6309 Spring ’12 UT-Dallas.

A Gift of Fire Third edition Sara Baase

Jacky: “Safety-Critical Computing …” ► Therac-25 illustrated that comp controlled equipment could be less safe. ► Why use computers at all, if satisfactory.

Software Quality Assurance

Planning and Tracking Software Quality Yordan Dimitrov Telerik Corporation

Introduction to Computer Technology

CommitCloseLaunchInvestLaunchBuildPlanExplore PRODUCT ENGINEERING – PLC COMMIT DECISION.

Release & Deployment ITIL Version 3

Software Failures Ron Gilmore, CMC Edmonton April 2006.

Lecture 7, part 2: Software Reliability

Dr Andy Brooks1 Lecture 4 Therac-25, computer controlled radiation therapy machine, that killed people. FOR0383 Software Quality Assurance.

DJ Wattam, Han Junyi, C Mongin1 COMP60611 Directed Reading 1: Therac-25 Background – Therac-25 was a new design dual mode machine developed from previous.

“Here’s why you need the new wheels, too…” Shawn and Steve Image from

Death by Software The Therac-25 Radio-Therapy Device Brian MacKay ESE Requirements Engineering – Fall 2013.

Product Quality, Testing, Reviews and Standards

 The software systems must do what they are supposed to do. “do the right things”  They must perform these specific tasks correctly or satisfactorily.

Planning and Tracking Software Quality.  What Is Software Quality?  Causes of Software Defects  What is Quality Assurance?  Improving the Software.

Therac-25 Final Presentation

FDA Docket No. 2004N-0133 Themes for Renewal of 21 CFR Part 11 Rule & Guidance by Dr. Teri Stokes, GXP International

Therac 25 Nancy Leveson: Medical Devices: The Therac-25 (updated version of IEEE Computer article)

Course: Software Engineering © Alessandra RussoUnit 1 - Introduction, slide Number 1 Unit 1: Introduction Course: C525 Software Engineering Lecturer: Alessandra.

Chapter 8: Errors, Failures, and Risk

Chapter 3: Software Maintenance Process Omar Meqdadi SE 3860 Lecture 3 Department of Computer Science and Software Engineering University of Wisconsin-Platteville.

Security and Reliability THERAC CASE STUDY TEXTBOOK: BRINKMAN’S ETHICS IN A COMPUTING CULTURE READING: CHAPTER 5, PAGES

DEFECTS By K.KARTHIKE. WHAT IS DEFECTS? Software bug, a failure of computer software to meet requirements Software bug The term defect and its relationship.

1.  Project: temporary endeavor to achieve some specific objectives in a defined time  Project management ◦ Dynamic process ◦ Controlled and structured.

Dimitrios Christias Robert Lyon Andreas Petrou Dimitrios Christias Robert Lyon Andreas Petrou.

Testing Workflow In the Unified Process and Agile/Scrum processes.

© 2008 Wayne Wolf Overheads for Computers as Components 2nd ed. System design techniques Quality assurance. 1.

Software Engineering 2 Software Testing Claire Lohr pp 413 Presented By: Feras Batarseh.

QUALITY ASSURANCE PRACTICES. Quality Plan Prepared and approved at the beginning of project Soft filing system approach followed. Filing location – –

Managing Change 1. Why Do Requirements Change?  External Factors – those change agents over which the project team has little or no control.  Internal.

Computing is Socio-Technical or: Why Stakeholder Listing is Inadequate for Thoughtful Ethical Analysis Chuck Huff St. Olaf College For NSF Computer Ethics.

Therac-25 CS4001 Kristin Marsicano. Therac-25 Overview  What was the Therac-25?  How did it relate to previous models? In what ways was it similar/different?

Defect Classes and the defect repository

Program Development Cycle

CS 1120: Computer Science II Software Life Cycle Slides courtesy of: Prof. Ajay Gupta and Prof. James Yang (format and other minor modifications by by.

Hussein Alhashimi. “If you can’t measure it, you can’t manage it” Tom DeMarco,

1 Developing Aerospace Applications with a Reliable Web Services Paradigm Pat. P. W. Chan and Michael R. Lyu Department of Computer Science and Engineering.

1 Software Maintenance and Evolution CSSE 575: Session 4, Part 2 Software Maintenance Process Steve Chenoweth Office Phone: (812) Cell: (937)

Project Planning Goal 1 - Estimates are documented for use in tracking and planning project. Goal 2 - Project Activities and commitments planned and documented.

Directed Reading 1 Girish Ramesh – Andres Martin-Lopez – Bamdad Dashtban –

USDA 2016 Financial Management Training Transforming Shared Services Change Management Presented by Ron Gros.

1 Advanced Computer Programming Project Management: Basics Copyright © Texas Education Agency, 2013.

Black Boxes and Due Process: Transparency in Expert Software Systems AAFS 2016 By Nathan Adams – Dan Krane –

1 March 19, Test Plans William Cohen NCSU CSC 591W March 19, 2008.

EE 585 : FAULT TOLERANT COMPUTING SYSTEMS B.RAM MOHAN

COMP60611 Directed Reading 1: Therac-25

A Gift of Fire Third edition Sara Baase

Reliability and Safety

CS 1120: Computer Science II Software Life Cycle

System design techniques

Therac-25: A Lesson Learned

Week 13: Errors, Failures, and Risks

CS 1120: Computer Science II Software Life Cycle

Software Maintenance Part1 Introduction. Outlines What Is Software Maintenance Purposes of Maintenance Why We Need It Maintenance Difficilties Some Tips.

A Gift of Fire Third edition Sara Baase

Presentation transcript:

Therac-25 : Summary Malfunction Complacency Race condition (turntable / energy mismatch) Data overflow (turntable not positioned) time‘85‘86‘88 ‘87 Micro-switch blamed and replaced Soft/Hardware changes ignored Overdose declared impossible Software fault identified Defective and CAP requested Software fault identified Defective and CAP requested Modifications (including hardware interlocks) approved Colin Barrett, Michael Pappas, Li Qingyi FDA notified by AECL

Therac-25 : Procedural Failings Only one software engineer In assembly language with bespoke scheduler Overreliance in software integrity No documentation for users or internally No Quality Assurance for software No meaningful testing strategy No understanding of the risks No design capturing full feature set and reuse If it wasn’t these bugs there probably were others Colin Barrett, Michael Pappas, Li Qingyi

Therac-25 : Procedural Failings Poorly conceived product from failed consortium Pressure to supress faults Ignoring previous incidents Fixes failed to find root cause Fixes to appease regulators (e.g. update micro- switch) Workarounds (remove  key) Only investigating hardware / external influences Colin Barrett, Michael Pappas, Li Qingyi N G Leveson, C S Turner, “An investigation of the Therac-25 Accidents”, IEEE Computing, Vol. 26 No pp