Re: Ariane 5 failure

[Ken Garlington <garlingtonke@lmtas.lmco.com>]

Robert I. Eachus wrote:
> 
> In article <96100111162774@psavax.pwfl.com> "Marin David Condic, 407.796.8997, M/S 731-93" <condicma@PWFL.COM> writes:
> 
>    Marin David Condic
> 
>    > It's not a case of saving a few CPU cycles so you can run Space
>    > Invaders in the background. Quite often (and in particular in
>    > *space* systems which are limited to rather antiquated
>    > processors) the decision is to a) remove the runtime checks from
>    > the compiled image and run with the possible risk of undetected
>    > constraint errors, etc. or b) give up and go home because there's
>    > no way you are going to squeeze the necessary logic into the box
>    > you've got with all the checks turned on.
> 
>    > It's not as if we take these decisions lightly and are just being
>    > stingy with CPU cycles so we can save them up for our old age. We
>    > remove the checks typically because there's no other choice.
> 
>    In this case though, management threw out the baby with the
> bathwater.  To preserve a 20% margin in the presence of a kludge
> already known to be applicable only to the Ariane 4, they took out
> checks that would be vital if the kludge ran on the Ariane 5, then
> forgot to take the kludge out.

The critical part of this correct statement, of course, being "In this 
case..". In another context, this might have been the right decision.

It's also important to remember that Ariane 5 didn't exist when the 
Ariane 4 team made this decision. They may have been short-sighted, but 
they weren't idiots based on what they knew at the time.

The Ariane _5 management not doing sufficient re-analysis and re-test of 
this "off-the-shelf" system is, to me, much less excusable.

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