1. MCAS does not behave exactly like a normal runaway trim.
2. On the Ethiopian crash, they _did_ initially follow the stab trim cutout procedure, but they didn't manage their speed correctly and thus were unable to control the plane with manual trim.
IMO point 2 is very important - pilots will not always be perfect. It's easy to armchair pilot from your couch and say that "Oh, just manage your speed correctly when your plane is trying to pitch itself into the ground just after takeoff and follow the stab trim cutout procedure. Very easy to deal with MCAS." But reality is not that easy.
> Look into history of comets and concorde if you want to look at hull loss rates
Compared to every other new plane released in the past 20 years, the 737 MAX has a terrible hull loss ratio. I don't really care about the Comet or the Concorde since it's 2019.
Agreed - pilots will not always be perfect, and if the safety chain -> design of systems, maintenance, training, experience is weaker than this will matter more.
Pilot error still #1 cause of fatalities including in the US. In this case bad maintenance also looks to be an issue and a brittle design. You have a master caution on 4 seconds into flight - you've got a terrible maintenance log book etc. I actually thought initial stab trim call wasn't unreasonably delayed - though they did let it run 4.6 to 2.1 over 10 seconds or so, which is a HUGE trim change.
And stab trim cutout wasn't followed fully or MCAS wouldn't have been able to put them into the ground at the end, though they may have already in a bad spot so thinking not unreasonable, except of course you might sit on nose up trim for a bit once reversing cutout.
The move will be I think to more automation and reducing ability to dispatch with things like a flight computer out of service (histrionically pilot skill would cover this now).
I also think they may need to move to authenticated maintenance / self test / parts life / history items. Ie, prevent dispatch on sloppy fixes / sloppy test.
1. MCAS does not behave exactly like a normal runaway trim.
2. On the Ethiopian crash, they _did_ initially follow the stab trim cutout procedure, but they didn't manage their speed correctly and thus were unable to control the plane with manual trim.
IMO point 2 is very important - pilots will not always be perfect. It's easy to armchair pilot from your couch and say that "Oh, just manage your speed correctly when your plane is trying to pitch itself into the ground just after takeoff and follow the stab trim cutout procedure. Very easy to deal with MCAS." But reality is not that easy.
> Look into history of comets and concorde if you want to look at hull loss rates
Compared to every other new plane released in the past 20 years, the 737 MAX has a terrible hull loss ratio. I don't really care about the Comet or the Concorde since it's 2019.