Here’s the actual safety board report, including flight data recorder graphs: http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/pre/2018/20...

Looks like there was a problem with the autopilot trim, likely due to a faulty sensor, and the pilot just needed to switch off the autopilot instead of fighting it — the previous flight of that aircraft experienced a similar issue, and they just turned the autopilot trim off and carried on normally. :(

The graphs on PDF page 23 are particularly morbid, and you’ll note that two of the final auto nose-down commands are of longer duration than all the rest.

Ah, this is quite good as well: https://leehamnews.com/2018/11/14/boeings-automatic-trim-for...

Apparently it wasn’t the standard autopilot trim, but a special safety program specific to the 737 MAX. Which still is just a switch to disable, if you know that switch is there, or that there is a checklist for dealing with runaway trim, or that you’re aware that auto-trim commands are the reason your plane keeps nosing down...

I think the most important point described in that article is that the MCAS trim, unlike the other kinds of elevator trim, isn't defeated by limit switches on the yoke - and that this critical information was not in the training or flight manual.

If true, then this right here is the problem root. Why isn't pilot limit respected with regard for the MCAS specifically? Are any other systems so independent?

I remember years ago the Boeing folks claiming that the automated Airbuses would be dangerous because the pilot always knows best. So how did it come to this on a Boeing?

The answer appears to be something along the lines of "because the whole point of MCAS is to stop the pilot flying the aircraft beyond the limits of stability".

> The graphs on PDF page 23

Just a note for anyone looking for these, I think this is a reference to the graphs on the PDF page labeled as Page 14. (The PDF has several pages before Page 1.)

If the autopilot tries to screw things up it is standard procedure to turn it off. Is failing to do so is human error? I guess so.

This wasn't the default autopilot but a new system, as such they didn't know what was causing the behaviour. On top of that all their sensors gave them different information.

> If the autopilot tries to screw things up it is standard procedure to turn it off. Is failing to do so is human error? I guess so.

You have a new automatic system pilots are not told about that will deep dive a plane with 200 people into the ocean unless you do things you have learned to apply in a different situation. I don't think you can call that a human error.. Except for maybe the human that decided not to tell the pilots?

And in the previous flight a similar team could handle it?

The Wikipedia article is quite good. https://en.wikipedia.org/wiki/Lion_Air_Flight_610