Originally Posted by
wonkazoo
Technically there are already as many parked as have been delivered. And a few more!! (Because they are all parked...)
This useless post brought to you by Light Always Airways. (LAA) "We spend lesser so you can go higher!!"
On an unrelated note: Who builds an airplane with two switches ostensibly in series, but in reality not so for one channel, to do the job of just one previously?? Who states that these are both "redundant??" when clearly they do different things?? What does that open channel between the FCC and God knows actually do, and since it didn't exist before can we safely accept that it is an artifact of MCAS??
I could go on for hours. The one thing our favorite expert and everyone else has right is this: We don't know squat. We know a lot, and from that we may draw inferences, but as to actual facts: We got stinko.
Here's the thing I do not understand (This will be the end of this lumbering and highly lubricated post I promise): Boeing creates a **** system that kills north of 300 people. OK,
Because I treasure all my fellow travelers, YokoDriver I'll help you out here: Boeing killed 300+ with the help of some less than stellar piloting.
OK, that's not good by any measure.
But then...
A few months go by...
And, according to YokoDriver Boeing gives the FAA some software to play with. (Now let's be clear here. By play with we mean molest completely and bend any way you can to try to make it break. Because that's what you do when your previous offering killed 300+ right??)
Anyway, and the point of the entire sad story is this: No matter how they got here, when the simulation was run:
THE FAA TEST PILOTS BARELY RECOVERED THE AIRPLANE AFTER IT TRIED TO SCREW ITSELF INTO THE GROUND.
Key phrase there: "THE AIRPLANE TRIED TO SCREW ITSELF INTO THE GROUND."
Only one of two possible things happened here.
a) The software tested was Boeing's original brew. Meaning not only is the now known MCAS AOA failure mode present, there was ANOTHER ONE, a failure mode that would try to screw the airplane into the ground.
or
b) Boeing sent over a "NEW" software package, and it had a failure mode that would try to screw the airplane into the ground.
Previous posters have argued indignantly using some of the points above, but seeing them in full is illuminating to say the least.
Can anyone please tell me why heads didn't explode with the headline last Thursday??
Either Boeing software had TWO flaws that would try to make a smoking hole in the ground, or they sent a new updated version to the FAA for a test-run with a flaw that would try to make a smoking hole in the ground.
Sorry for the lugubrious rant-
dce
Problem is, you can test that software well under normal conditions and under discrete non-normal conditions, but you cannot possibly test for every potential software error because there are far too many. So the methodology of Design Assurance is used, to the degree determined by the hazard classification.
This system has twice demonstrated that its malfunction (even with software acting as intended) must be classified as Catastrophic. This means that proper compliance requires DAL A. Question is, what is the current DAL of this software? While coding changes might be proposed and completed with relative simplicity, an upgrade of the DAL requires a complete reaccomplishment of the software development.
Not a trivial task at all, and one I fear the FAA would not choose to impose. Hopefully, other CAA, including EASA, will not be so accommodating. We’ll see. Well maybe they won’t let us see.