Re: Boeing and Dreamliner

[Marin David Condic <nobody@noplace.com>]

Rising to the bait, Marin writes... :-)

The important thing to remember is that the original designers 
*deliberately* stripped out the Ada safety features and *deliberately* 
designed the system to do exactly what it did. There was no bug here - 
it was a carefully considered engineering decision and, in the context 
of Ariane 4, it was the correct one. You're analogy of the 5 amp fuse in 
the 4 amp circuit is 100% on track. It was adequately designed for the 
original intended usage and then stuck in a different situation where it 
was not tested for the modified usage.

MDC


Mike Silva wrote:
> 
> 
> Good heavens, no, you're thinking of C!  There was no buffer overflow,
> and there was no bug.  There was a float-to-int conversion that was
> proven to be safe (FP value guaranteed to always fit into int) for the
> -4.  Therefore, any conversion overflow was assumed to be caused by a
> sensor/hardware problem and thus programmed by intention to shut down
> the SDI and let the backup system take over.  There is no way I can
> imagine that the -4 people can be accused of leaving a bug in the
> code.  To me the situation is akin to correctly specifying a 5 Amp
> fuse in a 4 Amp circuit, then "reusing" the circuit but now pumping 10
> Amps through it.  When the 5A fuse blows, was that a design error in
> the original circuit?



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Marin David Condic
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