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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,CP1252 X-Google-Thread: 103376,f039470e8f537101 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-07-21 20:11:11 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!bloom-beacon.mit.edu!nycmny1-snh1.gtei.net!news.gtei.net!newsfeed.mathworks.com!wn13feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi_feed4!attbi.com!sccrnsc03.POSTED!not-for-mail Message-ID: <3F1CAB38.1040300@attbi.com> From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Ariane5 FAQ References: <1058799152.775376@master.nyc.kbcfp.com> <1058810510.375902@master.nyc.kbcfp.com> <1058813341.841940@master.nyc.kbcfp.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit NNTP-Posting-Host: 66.31.71.243 X-Complaints-To: abuse@comcast.net X-Trace: sccrnsc03 1058843470 66.31.71.243 (Tue, 22 Jul 2003 03:11:10 GMT) NNTP-Posting-Date: Tue, 22 Jul 2003 03:11:10 GMT Organization: Comcast Online Date: Tue, 22 Jul 2003 03:11:10 GMT Xref: archiver1.google.com comp.lang.ada:40602 Date: 2003-07-22T03:11:10+00:00 List-Id: Vinzent Hoefler wrote: > Ok, so change the entire brake controller. ;-) What reason makes you > think, it will work? A better example would be to take a brake system from a car and put it into a truck. But the box for the brake system was labeled "for MVW up to 5,000 pounds," and it is a 2 1/2 ton truck. This is what you have to keep the focus on. The problem was not that the engineers for the Ariane 4 inertial guidance system didn't do their job perfectly, or that the engineers for the Ariane 5 didn't do their jobs correctly. Management put a box on the org chart and the engineering test plan which said that these people will make sure that the Ariane 4 inertial guidance software will work on the Ariane 5. Then they literally erased the box without staffing it, with the intent of saving money. So as things worked out no engineer was ever in a position to give an opinion on whether the inertial guidance software was suitable for the Ariane 5. It really happened that (if you read Dilbert) a pointy haired boss took the software out of the box and handed it to the Arine 5 construction team saying it had been throughly tested for this job. But no engineer ever saw both the Ariane 5 requirements and the Ariane 4 inertial guidance software documentation until after the crash. And the elimination of the "full-up" engineering tests of the inertial guidance software with the engine controls was cancelled for lack of funds and lack of time after all the engine system design engineers had gone on to other projects. It would be nice if there was a particular culprit who knew that the reason the full-up guidance system tests were behind schedule because the guidance software didn't work. But in reality, the testing was so far behind schedule when it was cancelled that they never got as far as running with the computers the software ran on integrated into the test stand. (And the test platform was being done as "black box" testing, so the test developers had access to the Ariane 5 requirements--but not the actual software documentation, just the interfaces.) I would love to be able to say that "it could never happen here." But I can't, it takes constant vigilance on a project to ensure that there are no loose ends, missed requirements or requirements that have changed since the original analysis. So in the end it comes down to the fact that we are all only human. -- Robert I. Eachus �In an ally, considerations of house, clan, planet, race are insignificant beside two prime questions, which are: 1. Can he shoot? 2. Will he aim at your enemy?� -- from the Laiden novels by Sharon Lee and Steve Miller.