From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,885dab3998d28a4 X-Google-Attributes: gid103376,public From: Ken Garlington Subject: Re: Ariane 5 failure - latest S/W tech vs. cold hard facts Date: 1996/10/10 Message-ID: <325D3FE3.63E0@lmtas.lmco.com>#1/1 X-Deja-AN: 188729339 references: <96100112290401@psavax.pwfl.com> <32531A6F.6EDB@dynamite.com.au> <3252B46C.5E9D@lmtas.lmco.com> <531mdv$tfm@flood.weeg.uiowa.edu> <537ggl$mc8@flood.weeg.uiowa.edu> content-type: text/plain; charset=us-ascii organization: Lockheed Martin Tactical Aircraft Systems mime-version: 1.0 newsgroups: comp.lang.ada x-mailer: Mozilla 2.02 (Macintosh; I; 68K) Date: 1996-10-10T00:00:00+00:00 List-Id: Robert S. White wrote: > > In article , dewar@schonberg.cs.nyu.edu says... > > >There are certainly cases where careful consideration of these three factors > >still results in a decision to use less hardware and more complex software, > >but I think we have all seen cases where such decisions were made, and n > >in retrospect turned out to be huge mistakes. > > In business when making hard decisions about embedded systems products, > such studies are almost always made. In my experience, both statements are true. Such studies are often made, and I have also seen cases where they weren't made, or were done poorly. I have no idea what the percentages are for: * the study was done correctly * the study was not done correctly (or not done at all), but the decision turned out to be right anyway * the study was done incorrectly, the answer was wrong, and no one ever discovered it was wrong (because no one ever looked at the final cost, etc.) * the study was done incorrectly, the answer was wrong, someone found out it was wrong, but didn't broadcast it to the general public (would you?) Overall, I'd say we'll never know. As a colleague of mine said: "How many systems out there have a bug like the Ariane 5, but just never hit that magic condition where the bug caused a failure?" Just think: A little less acceleration on takeoff, and we'd think Arianespace made a wonderful decision by reusing the Ariane 4 -- look at all the money they saved! It might have been mentioned in the Reuse News as a major success :) I've got a few minutes, so I'll mention another of my favorite themes at this point (usually stated in the context of preparing Ada waivers): It's really hard to determine the life-cycle cost of software, particularly over a long period (e.g. 20 years). There are cost models; sometimes, we even get the parameters right and the model comes up with the right answer. Nonetheless, it's tough to consider life-cycle costs objectively. That's not an excuse for failing to try, but an acknowledgement that it's easy to get it wrong (particularly for new technology). Software engineering can be _so_ depressing! -- LMTAS - "Our Brand Means Quality" For more info, see http://www.lmtas.com or http://www.lmco.com