I have been following this thread, and read some more after Googling around. A copy of the Nancy Leveson IEEE report is available on the net.
http://courses.cs.vt.edu/~cs3604/lib/Therac_25/Therac_1.html It is very complete, and written in terms of Understatement...... A few remarks: The single fact that even one patient complained About a burning pain during radiation exposure should, no MUST have been enough to ring all available alarm bells. If one reads to what extend safety measures were ignored, one can say only one thing: this company has acted amoral. (even in 1985) Hey this was not prehistoric !!! Even from a medical/functional point of view: Giving hazardous treatments to patient without a operator/treatment log available on paper (excuse: no memory in a PDP-11 ???? ) is asking for errors. The absence of this log made it impossible to trace down what exactly went wrong. The type of software bugs (that are discussed in detail in this report) are those made by programming beginners. Even In 1985. I have been programming in 1984 on modem technology and clearly remember how magazines like Byte discussed programming technologies on microprocessors, and discussions about testing software were already common stuff. I personally made use of a Byte published text editor In 1982 (assembler), and of a multitasking kernel for the 8080 series. The article discussed the problems that go with parallel processing and offered several mechanisms for the problems like race conditions that deal with that, such as semaphores. The technique of incrementing a byte as a flag for setting it, and relying on not being zero for a fault condition goes wrong every 256 settings. How stupid can one be !!!! It's a beginners fault one makes once only! I think that article is still very nice to the manufacturer of this Therac 25. Gert Gremmen Ce-test, qualified testing bv Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens John Woodgate Verzonden: zaterdag 10 mei 2008 7:46 Aan: emc-p...@ieee.org Onderwerp: Re: Ethics grad work Therac-25 In message <4bea4e50d3d4344da9d84367ae31706402195...@dcexvs02.tennant.tco.corp>, dated Fri, 9 May 2008, "Bender, Curtis" <curtis.ben...@tennantco.com> writes: >What EXACTLY are the manufacturer's root ethical issue(s) here? I have >the following so far: > >0.) doing a software safety analysis AFTER the machine has been >commercially available - what kind of motivation would the manufacturer >have to pass!! Even from the 'amoral' business viewpoint, the motivation is that the consequences of doing it might be more favourable than those of not doing it - as proved to be so. >1.) Releasing software that that had an insufficient safety analysis - >was fault tree bad or was that accepted practice in 1983? Not enough was generally known about software safety at that time. Probably even less about how to check for safety. > if 1.) is not the root, then: >2.) Inadequate response to 6 injuries/overdoses in 9 months. this was a >million dollar machine but hey, what is the value of a human life? It's not clear 'who knew what, when?'. Was there enough evidence that at least some of the accidents were not due to operator error, for example. >3.) Knowingly leaving an unsafe product on the market for 10 months >until units were required to be shutdown by the FDA & CRPB. same >comment as above. 'Knowingly' is a big word. Did anybody actually 'know'? Or even 'suspect'? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
