Ariane5 FAQ, 3rd draft

Ariane5 FAQ, 3rd draft

[Alexandre E. Kopilovitch]

In this 3rd version one more Q-A pair is added, and another A is edited slighly.

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Q. Was Ada language somehow related to Ariane 5 crash in 1996?

A. Yes, at least some components of the Ariane 5 software was written
in Ada language.

Q. Did that software cause the crash?

A. Yes and No. They simply put the software written for previous model --
Ariane 4 (where it worked well) -- to new Ariane 5, and did not bother
themselves with testing it on the new rocket before the launch. So, when
the Ariane 4 software appeared (in the flight) incompatible with new Ariane 5
they became very surprised -- and blamed the software.

Q. But media told us that there was an error in the software that caused
that crash. Is it right?

A. No, it is wrong. There was no such an error in the software. The software
worked perfectly for the purpose, for which it was created, that is, for
Ariane 4. The software was not created for Ariane 5, and there were no reasons
to expect that it should work for this new rocket. So, the error, which caused
the crash was blinded use of a software created for another job. And this
error was severely aggravated by subsequent error -- skipping mandatory test
procedure before the first flight.

Q. But why on earth they expected that it should work if they have no reasons
for it? Are you implying that they were idiots? (No conspiracy theories please.)

A. No. There was an unfortunate collision of popular expectations about modern
high-tech devices with real difficult issues of international collaboration
in sensitive technologies.
  Ariane 5 was an international project (within European Union), and at the
same time it naturally belonged to an area of high secrecy (which is, as you
probably know, traditionally maintained within strictly national frame).
This created a difficult issue and caused uncommonly massive involvement of
persons with political, diplomatic, economical etc. rather than technical
background and/or experience into the high management of the project.
  Those persons naturally have mostly consumer-like expectations about modern
high-tech devices. This means that while they may be generally smart and able
to occupy some position within large technical project, nevertheless they have
different (from an engineer) default assumptions for many technical issues.
  So they dealt with one critical part of the equipment as if it was some
regular consumer market product from a reliable vendor: they assumed that they
may use the device in all circumstances that aren't explicitly and clearly
prohibited in its documentation. Because of their insufficient engineering
background and/or experience they weren't aware of the difference in this
respect between a complete product and its component part -- they did not know
well enough that for the latter the defaults are opposite, that is, you should
not use the component device in any circumstances that aren't explicitly and
clearly allowed.

Q. But certainly there were engineers also, who can see possible consequences
of that approach. So why they weren't alarmed enough?

A. This is difficult question indeed. An explanation exists, which tells that
the informational paths within the project were interspersed with those 
managers of non-engineering kind, and because of that no one of the engineers
can obtain enough information for recognition of the danger. It is up to you
to decide whether this explanation is sufficient enough.

Q. Can you explain in several words what was the actual cause of the launch
failure, technically?

A. There are several points which are different for Ariane 5 vs. Ariane 4,
one of which was instrumental to the events: Ariane 4 is a vertical launch
vehicle where as Ariane 5 is slightly tilted.
  Ariane 4 software was developed to tolerate certain amount of inclination
but not as much as required by Ariane 5. The chain of events were as follows:

- The on-board software detects that one of the accelerometers is out of range,
this was interpreted as hardware error and caused the backup processor to take
over;
- The backup processor also detects that one of the accelerometers is out of
range, which caused the system to advice an auto destruction.

Q. Where I can find official report for the investigation of the Ariane 5
crash?

A. At the moment of writing this FAQ this report was, for example. at:
 http://www.dcs.ed.ac.uk/home/pxs/Book/ariane5rep.html
But read it to the end, because your overall impression will probably be
different (and wrong) if you stop in the middle of it, deciding that you
got it all clear enough.

Q. Where this topic was discussed in depth?

A. For example, in comp.lang.ada newsgroup (several times). Search that
newsgroup for "Ariane 5", and you'll find several threads discussing this
topic (most recent at the moment of writing this FAQ was quite long thread
with subject line "Boeing and Dreamliner").

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Re: Ariane5 FAQ, 3rd draft

[Hyman Rosen]

Alexandre E. Kopilovitch wrote:
>   Those persons naturally have mostly consumer-like expectations

I'm curious as to what your sources are for these beliefs.

Re: Ariane5 FAQ, 3rd draft

[Alexander Kopilovitch]

Hyman Rosen wrote:

>  Alexandre E. Kopilovitch wrote:
> >   Those persons naturally have mostly consumer-like expectations
>
>I'm curious as to what your sources are for these beliefs.

First, your question will definitely look better with slighly more quoting
before it, something like this:

> >... persons with political, diplomatic, economical etc. rather than technical
> >background and/or experience into the high management of the project.
> > Those persons naturally have mostly consumer-like expectations about modern
> >high-tech devices.
>
>I'm curious as to what your sources are for these beliefs.

Second, I'm not sure for which part of the statement you are asked for the
sources: are you in doubt that "persons with political, diplomatic, economical
etc. rather than technical background and/or experience" should have "mostly
consumer-like expectations about modern high-tech devices", or you are wondering
why that is "natural"?



Alexander Kopilovitch                      aek@vib.usr.pu.ru
Saint-Petersburg
Russia

Re: Ariane5 FAQ, 3rd draft

[Hyman Rosen]

Alexander Kopilovitch wrote:
> Second, I'm not sure for which part of the statement you are asked for the
> sources: are you in doubt that "persons with political, diplomatic, economical
> etc. rather than technical background and/or experience" should have "mostly
> consumer-like expectations about modern high-tech devices", or you are wondering
> why that is "natural"?

Do you have any evidence that the people involved in
decision making for the Ariane 5 were as you characterize
them? That is, that they did not have technical background
and/or experience?

I find this to be a dubious claim, because I do not believe
that such a person would have the expertise to be able to
say that some subsystem should or should not be tested.

Re: Ariane5 FAQ, 3rd draft

[Wojtek Narczynski]

Alexandre,

> A. There are several points which are different 
> for Ariane 5 vs. Ariane 4, (...)

IMHO, this is *the* answer. And thanks for posting it. The no.1
question would be "Why did it crash?". Would you consider putting it
as the first one? The rest just fill in the details, or - depict the
climate.

Regards,
Wojtek

Re: Ariane5 FAQ, 3rd draft

[Alexander Kopilovitch]

Wojtek Narczynski wrote:

> > A. There are several points which are different
> > for Ariane 5 vs. Ariane 4, (...)

>IMHO, this is *the* answer. And thanks for posting it.

Note though, that this "A" in the FAQ is essentially a copy of
Francisco Malpartida's posting (from 21 Jul 2003,
Message-ID: <3f1c374f$0$11375$cc9e4d1f@news.dial.pipex.com>),
with very slight editorial changes.

>The no.1
>question would be "Why did it crash?". Would you consider putting it
>as the first one? The rest just fill in the details, or - depict the
>climate.

Various people may have different views about what is most interesting
(or most hot) question in the Ariane 5 launch failure story. Surely
there may be various designs for this FAQ. I didn't make any design
at all, so far the FAQ is developed by "natural way" -- every time when
I see new info deserved to be included, or a gap to be filled, I add new
Q-A pair, inserting it at the place that seems suitable at that moment.
I don't think that I'm going to make any particular design for the FAQ,
mainly because I have no grounds for that. But this does not prevent any
people to propose their own (full) designs, and even to take over with
whole this burden -:) .



Alexander Kopilovitch                      aek@vib.usr.pu.ru
Saint-Petersburg
Russia

Re: Ariane5 FAQ, 3rd draft

[Warren W. Gay VE3WWG]

"Alexander Kopilovitch" <aek@vib.usr.pu.ru> wrote in message news:e2e5731a.0307260702.46227d7e@posting.google.com...
> Wojtek Narczynski wrote:
>
> > > A. There are several points which are different
> > > for Ariane 5 vs. Ariane 4, (...)
>
> >IMHO, this is *the* answer. And thanks for posting it.
>
> Note though, that this "A" in the FAQ is essentially a copy of
> Francisco Malpartida's posting (from 21 Jul 2003,
> Message-ID: <3f1c374f$0$11375$cc9e4d1f@news.dial.pipex.com>),
> with very slight editorial changes.
>
> >The no.1
> >question would be "Why did it crash?". Would you consider putting it
> >as the first one? The rest just fill in the details, or - depict the
> >climate.
>
> Various people may have different views about what is most interesting
> (or most hot) question in the Ariane 5 launch failure story. Surely
> there may be various designs for this FAQ. I didn't make any design
> at all, so far the FAQ is developed by "natural way" -- every time when
> I see new info deserved to be included, or a gap to be filled, I add new
> Q-A pair, inserting it at the place that seems suitable at that moment.
> I don't think that I'm going to make any particular design for the FAQ,
> mainly because I have no grounds for that. But this does not prevent any
> people to propose their own (full) designs, and even to take over with
> whole this burden -:) .

I think the suggestion is a good one, myself. This FAQ is likely to
grow, as this thread repeats itself (and frequently).  Most people read
as far as they need to get to the answer they need (or disagree with).

State the conclusion up front. If people agree and don't care about the
details, then they don't need to read further. If they violently disagree,
or not yet sure, or just want to know more, then they know up front
that they need to read more.

I don't think it is much a burden to move the section to the start
is it? Perhaps in the next editorial round? ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg

Re: Ariane5 FAQ, 3rd draft

[Alexander Kopilovitch]

Warren W. Gay wrote:

> > Wojtek Narczynski wrote:
> >
> > > > A. There are several points which are different
> > > > for Ariane 5 vs. Ariane 4, (...)
> > > > ...
> > >The no.1
> > >question would be "Why did it crash?". Would you consider putting it
> > >as the first one? The rest just fill in the details, or - depict the
> > >climate.
>
> I think the suggestion is a good one, myself. This FAQ is likely to
> grow, as this thread repeats itself (and frequently).  Most people read
> as far as they need to get to the answer they need (or disagree with).
>
> State the conclusion up front. If people agree and don't care about the
> details, then they don't need to read further. If they violently disagree,
> or not yet sure, or just want to know more, then they know up front
> that they need to read more.

Well, I understand these reasons.

> I don't think it is much a burden to move the section to the start
> is it? Perhaps in the next editorial round? ;-)

Unfortunately, I do not see this that simple. That move definitely breaks the
"unfolding" logic of the FAQ in its current state (I tried and saw that).
Actually I think that the reasons you stated are part of entirely another
approach to the FAQ, which is certainly no less possible and no less good --
it is just optimized another way, for another usage mode. Essentially the same
information, but another order and correspondily, another "unfolding logic".
I'd like to call these two versions of the FAQ as "Observer's" (current)
and "Professional" -:)  If this FAQ eventually will be placed on some WWW site
then it is possible indeed to have both versions there... guite gorgeous -;)
In fact, some important information is much easier to include in that
"Professional" version (I still can't find a suitable place for it in current
version). Perhaps, the "Professional" version will take over at the end, but
for now I can rely on "Observer's" approach only, all others are secondary
for me. (But certainly. those people for whom that "Professional" approach is
natural, may propose their own full designs of the FAQ.)



Alexander Kopilovitch                      aek@vib.usr.pu.ru
Saint-Petersburg
Russia