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,ASCII-7-bit X-Google-Thread: 103376,f948976d12c7ee33 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-06-23 23:22:28 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!arclight.uoregon.edu!wn13feed!wn12feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi_feed4!attbi.com!sccrnsc01.POSTED!not-for-mail Message-ID: <3EF7EE09.7040505@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: Boeing and Dreamliner References: <3EF5F3F3.6000806@attbi.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 24.62.164.137 X-Complaints-To: abuse@attbi.com X-Trace: sccrnsc01 1056435730 24.62.164.137 (Tue, 24 Jun 2003 06:22:10 GMT) NNTP-Posting-Date: Tue, 24 Jun 2003 06:22:10 GMT Organization: AT&T Broadband Date: Tue, 24 Jun 2003 06:22:10 GMT Xref: archiver1.google.com comp.lang.ada:39635 Date: 2003-06-24T06:22:10+00:00 List-Id: Alexander Kopilovitch wrote: > No, simple "stupid management" is not enough here. Something more technical > was rotten. There was not single decision (or couple of decisions) taken by > top level manager at the last moment - there was nothing like ordering a > launch despite inappropiate weather. It was a long project with many presumably > competent people involved; and it is important to investigate more deeply: > why consequences of initial wrong decision (which was made by incompetent > people) were not recognized by scientific and technical staff before the > actual failure happened. I can give you some of the answers from memory, but the best thing to do is to actually read the technical report on what happened. (I found a copy at http://www.dcs.ed.ac.uk/home/pxs/Book/ariane5rep.html) There are a number of places where the international politics are not included in the technical report. But some political details are important. The French didn't want Germans getting access to the Ariane 5 performance data, even though the SRI software was written by the English subsidiary of a German company, if I remember right. But the real cap on the whole thing was that there was supposed to be a full up test rig which would allow system test for the gyros, the computers and the engine controls. This test platform was behind schedule so the French decided to go ahead and launch without doing the test! I don't know about the formal test methods in Russia, but in the US the common practice is to come up with a set of test objectives, then assign them to one of four major categories. In effect what happened was that ALL the guidance and engine control subsystems test objectives that were supposed to be Demoed (i.e. demonstrate that the subsystem does what it is supposed to do in operation) were signed off without ever being run. But to me the crowning idiocy of the whole thing is in one sentence of the report: "The main explanation for the absence of this test has already been mentioned above, i.e. the SRI specification (which is supposed to be a requirements document for the SRI) does not contain the Ariane 5 trajectory data as a functional requirement." The SRI requirements document was never updated for the Ariane 5, and as I pointed out, the software had built in parameters that reflected physical constants relating to the Ariane4. Also, it doesn't take a genius to tell you what that ten second period of "pressure surges" in the flight control hydraulics was. But of course the politics of the situation kept the fact that oscillations were building up in the stack from being an obvious part of the official report--and from being left out of it: "One anomaly which was brought to the particular attention of the Board was the gradual development, starting at Ho + 22 seconds, of variations in the hydraulic pressure of the actuators of the main engine nozzle. These variations had a frequency of approximately 10 Hz. "There are some preliminary explanations as to the cause of these variations, which are now under investigation. "After consideration, the Board has formed the opinion that this anomaly, while significant, has no bearing on the failure of Ariane 501." Don't you just love that attempted slight of hand? The stack was swinging back and forth ten times a second. (Of course it was, the control systems model didn't match the actual system.) Before the oscillations got too bad, this other thing destroyed Ariane 501. Of course, if you just fix that other bug, Ariane 502 will go boom! a little higher up. But we aren't going to say that in public.