Originally Posted by
BDAttitude
Well, TBH I don't hope anyone would have gone airborne with an FCC not completing is POST.
Well, yeah. It isn't quite "nothing to see here", but this is exactly the sort of failure you can sometimes get with
any software system going from test or staging environments (eng sim) to production - test never
quite does things exactly the same. Looks like failure happened at the right place/time (ie. on the ground) and was caught by the existing self-checks.
The surprising thing for me is that this appears to mean they have
not yet flown the final fix. So are all those previous test flight useless now? Was this the reason for the test-flight hiatus - ie. not that they'd finished testing (as some said) but that the software wasn't final yet?
This confirmes (once again) that the changes done to implement inter communication and health checking between the two boxes and fixing this dubious AP disconnect issue, which must have something to do with the task scheduling, were in fact open heart surgery on these old architectures.
What could possibly go wrong?
Well, it hints rather than confirms, but I'd bet that it was that change causing problems as well.
Reading between the lines, I get the impression they are now seriously short of spare CPU cycles in the FCC (my guess is that they were before this issue, possibly even before MAX, and were just hoping they wouldn't need any...). If so, they will now be trying to save cycles anywhere they can (been there, done that, not thankfully on passenger aircraft code...), which is really really bad news. What could possibly go wrong? - anything, Anything they mess with to save cycles, and everything else as well if they actually have started to mess with task scheduling, latent bugs, race conditions, new timing issues, things that haven't surfaced in the life of the NG, and would have stayed hidden, could now be unleashed. Or of course it could all be just fine, nothing to see here, feel the force...
Wondering now how many test flights the new new fixed software will need (once it actually boots properly), and how long after that to certify it?