Originally Posted by
Alchad
"Slacktide" posted a question (post 1337) on the Indonesian 610 thread asking why stabiliser cut out switches had been relabelled. As far as I could see, nobody had any views, just though I'd ask again as I'm also curious!
I think I asked about this too at one point on one thread, I vaguely recall that there was a sort-of answer that they are now "primary" and "backup" cutouts and
both of them cut
both (auto and main-elect) circuits. This implies there is no way to cutout STS/MCAS and still have manual electric trim, I think. However, I am not sure we got an answer as to
why they have changed or whether this change has been properly communicated to pilots.
Take this quote from a MAX ASRS report:
confusion regarding switch function [...] related to ‘poor training and even poorer documentation
The First Officer offered to hit the SEL function in flight, to test it out, but I thought something irreversible or undesirable might happen (not knowing what we were actually selecting), so we did not try it out in flight.
Then add in the fact that these re-labelled and (possibly) re-purposed switches are the very ones the accident crews were expected to use to control MCAS...
I should stop there (or earlier) since I'm only an engineer flying an armchair, but this smells too much like the times in my career when development/sales/delivery/training have all blamed the end user for a ****up, yet when I have been the one to sit down with the end users I have found that between development/sales/delivery/training we have produced a system that an average user was
inevitably going to ****up at some point. I'm lucky, those times have not been in aviation, the worst consequence was data loss (and maybe contract loss, bonus loss...), but nobody died - but it
shouldn't happen in aviation, it
should be caught before it gets in front of an "average end user" with a plane load of pax behind them.