Re: Boeing and Dreamliner

["Robert I. Eachus" <rieachus@attbi.com>]

Hyman Rosen wrote:

> This is the report: <http://java.sun.com/people/jag/Ariane5.html>.
> This is a quote from the report:
>     The Board has also noted that the systems specification
>     of the SRI does not indicate operational restrictions
>     that emerge from the chosen implementation. Such a
>     declaration of limitation, which should be mandatory for
>     every mission-critical device, would have served to
>     identify any non-compliance with the trajectory of Ariane 5.
> 
> So I can believe you, or I can believe them. Which shall it be?

How about believe both?  As I said:

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."

If I write a program for a washing machine, should the requirements spec 
include: "This software is unsuitable for the Ariane 5, whatever that is?"

The software for the Ariane 4 met the all the functional requirements in 
the systems specification for the SRI.  If it didn't, of course that 
should have been documented in the systems specification.  But the 
software was not suited to launching an Ariane 4 from Mars or Venus. 
Did it say that?  Of course not, there was no requirement for launching 
an Ariane 4 from anywhere other than the surface of the Earth.

Asking the writers of the SRI functional specification to imagine all 
the possible uses someone might try in the future to use the SRI 
for--including washing machines--is crazy.  What was required, and 
didn't happen, was for the Ariane 5 project to write a requirements 
document for the SRI, and then either test to those requirements, or 
evaluate the existing Ariane 4 test data to show that the SRI met the 
Ariane 5 requirements.  None of that was done, and Ariane 501 destroyed 
itself.