Yo
gums,
Further to my comments on your additional request for ‘aero’ explanation (
Ethiopian airliner down in Africa) see the following:-
‘
During design of the MAX, Boeing added two more leading-edge vortilons [generating vortices over the top of the wing at high AOA] in 2018, for a total of six per side and also lengthened and raised the inboard leading-edge stall strips to assure stall behavior would be as docile as that of the NG’.
(
https://www.twu557.org/index.php/new...x-new-software)
This suggests that Boeing had identified issues earlier than I suggested; also because of the nature of the changes the aero effects were more significant than currently being discussed for MCAS.
The use of vortilons might be a simple alternative to adding many more vortex generators, but stall strips to reinforce the inner-wing stall before outboard sections, opposing pitch up, is more like ‘a new aircraft’ fix.
A very crude comparison of the effects of nacelle lift might be made with military blended wing / fuselage, or leading edge extensions; what ever these provide for the fighter world then its not helpful in commercial aviation - or at least a same type rating for the 737 MAX.
Also, Boeing ‘
Commenting on criticism of the single string failure potential of the AOA input to MCAS, a Boeing official said the original design was based on a standard industry process of hazard classification which defined the potential failure as one that could be mitigated “very quickly performed by a trained pilot using established procedures”.
Add to that, a remarkable comment from the FAA; “
Pilots of large aircraft are trained from Day 1. When the pitch of the aircraft is doing something you’re not telling it to do, you do a runaway pitch trim checklist,” Acting FAA Administrator Dan Elwell, a former airline pilot …
This does not add confidence that the FAA have a good understanding of training, nor the much wider safety aspects of loss of control (for wind-shear / turbulence pitch up - do we always inhibit trim ! )
https://www.twu557.org/index.php/new...-human-factors
Then re the training discussion:-
‘
Pilots for three U.S. air carriers tell … that during their sim training they had never been exposed to extreme and continuous AOA indication errors, they’ve not experienced AOA induced airspeed and altitude deviations on PFDs and have not had to deal with continuous stall-warning stickshaker distractions. They also note that they have never been required to fly the aircraft from the point at which a runaway stab trim incident occurred all the way to landing using only the manual trim wheels. “We’re just checking boxes for the FAA,” says one Seattle-based pilot’.
P.S. some web links may be transposed, or changed by the host site - search news items (I’m working on it).