[SystemSafety] [External] Re: "FAA chief '100% confident' of 737 MAX safety as flights to resume"

[Peter Bernard Ladkin]

On 2020-11-25 00:22 , Tom Ferrell wrote:
> Glad you are amused, Peter.  

Did you maybe misunderstand? I meant what I wrote.

> The safest thing to do with the max is to permanently ground this variant and not attempt to 
> overcome the inherent aerodynamic instability in a certain flight regime.  

I distinguished between aerodynamic instability, which is a tendency to diverge from a trimmed 
unaccelerated flight attitude, and the particular kind of stability involved here, which is that in 
a particular flight regime the stick forces stop rising (and maybe become lighter) as AoA becomes 
higher. That is what "aerodynamic stability" means in Europe.

The FAA calls it "longitudinal stability", I believe.

Your views on how the engineering-safety culture at Boeing eroded seem to be held by many. I was 
reading them ten years ago on PPRuNe, and I believe they also come out of the U. Puget Sound 
studies, Greenberg, Grunberg, Moore, Sikora and then Grunberg, Moore, but I haven't read those.

> I was involved in looking for the byzantine type faults he mentions in the AIMS system.  

I thought it was the control system, not AIMS, which exhibited Byzantine-type failures.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
ClaireTheWhiteRabbit RIP
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de