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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Ariane 5 - not an exception?
Date: 1996/08/24
Message-ID: <EACHUS.96Aug23201508@spectre.mitre.org>#1/1
X-Deja-AN: 176073841
references: <4vgmit$124@goanna.cs.rmit.edu.au> <4vk8r4$2r7@zeus.orl.mmc.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: comp.software-eng,comp.lang.ada,comp.lang.pl1
Date: 1996-08-24T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <4vk8r4$2r7@zeus.orl.mmc.com> rgilbert@unconfigured.xvnews.domain (Bob Gilbert) writes:

  > ...It is my impression that they concluded that an analysis of the
  > conversions was done, and a conscious decision to omit them was
  > (wrongly) made, in part to meet their 80% processor utilization
  > goal (something some have suggested should have been waived in
  > this circumstance)...

  > As you say, an analysis was done and checks added where they felt it
  > was necessary.  Sounds like the analysis, which determined the
  > requirements, was in error...

    There is one detail you seem to have missed.  The analysis was
correct for the Ariane 4.  The incredible management blunder was that
reanalysis was not done for the Ariane 5, because the plan was to test
the actual hardware (and software) instead.  But later changes in
plans eliminated the full up testing.  So the software was not written
to Ariane 5 specifications--in fact the report specifically states
that the developers never had access to those specifications.  The
software was never analyzed with respect to those specifications. And
the software and hardware was never tested against those different
specifications.

    I would be be fired three times over for incompetent engineering
on that scale, and so would you.  But the decisions were political and
managerial.  I can't overemphasize this.  The decisions which caused
the failure were signed off not by engineers but by government
ministers and corporate executives.  And the effect, not the intent of
those decisions insured that the engineers never knew how badly things
were being botched.  It speaks well for the consortium that they did
an honest evaluation of what went wrong and published it.
Unfortunately it was clearly bowdlerized and mentions no names.  I
suspect that this was a condition imposed upon publishing it.





--

					Robert I. Eachus

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