Re: F-22 Raptor software problem

On Feb 27, 6:33 am, "Bob Spooner" <r...@xxxxxxx> wrote:
"Aurele" <aurele.vit...@xxxxxxxxx> wrote in message

news:1172502110.098416.297700@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> On Feb 26, 3:55 am, "Alex R. Mosteo" <devn...@xxxxxxxxxxxxxx> 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.

.