Re: F-22 Raptor software problem

[JPWoodruff@gmail.com]

On Feb 27, 6:33 am, "Bob Spooner" <r...@psu.edu> wrote:
> "Aurele" <aurele.vit...@gmail.com> wrote in message
>
> news:1172502110.098416.297700@q2g2000cwa.googlegroups.com...> On Feb 26, 3:55 am, "Alex R. Mosteo" <devn...@mailinator.com> wrote:
>
> > Well, someone is likely to lose their job for improperly implementing
> > the geoid and/or datum model!
>
> I would be inclined to think that the (derived) requirements were
> incompletely specified and therefore didn't cover the case of what happens
> when the nav system, while using GPS signals for time, crosses the date line
> (or something like that.)  -- Bob


Something's bothering me about this case, and hasn't been mentioned
yet.

I think I'm correct in guessing that this aircraft has been in service
for some time. If that's true, then almost certainly some F-22 has
crossed the dateline without difficulty in the past. So it's a change
in the software that started the failure.

My own experience taught me it's difficult to assure integrity as a
large system evolves. The system needs an effective configuration
control board, and that team needs a really sound process.  This is
easier said than done.   We can hope that practical "lessons learned"
will be shared when this case has been analyzed.