Michael_J wrote:
What ever happened to “look at the instruments (gyro horizon) and fly the plane”?
You do know that an aircraft like the B737 it impossible to control if the stabiliser trim is too far off?
Yes, but that was not the point. I was thinking of the need to have a system such as the MCAS.
Michael_J wrote:
I was thinking of the need to have a system such as the MCAS.
Certification requirements. Sorry, but I don’t see your point with “fly the plane”.
Michael_J wrote:
I was thinking of the need to have a system such as the MCAS
I think “as normal pilot with 150pax” you simply can’t fly the B737Max without MCAS (unlike autopilot or trim) but I will wait to see what investigators and external opinions come up with on this (not certified does not mean impossible to fly, but the FAA had a genuine stability concern before the MCAS was introduced)
Ibra wrote:
I think “as normal pilot with 150pax” you simply can’t fly the B737Max without MCAS (unlike autopilot or trim) but I will wait to see what investigators and external opinions come up with on this (not certified does not mean impossible to fly, but the FAA had a genuine stability concern before the MCAS was introduced)
I don’t think it did. This was all about certification re stall recovery not stability.
JasonC wrote:
This was all about certification re stall recovery not stability.
Yes it comes from certification requirements but that “stall protection in recovery” will come at the cost of “pitch instability” when the thing is OFF, I don’t think that has been tested/challenged that much in certification. The big issue is that the specs of MCAS were never clearly defined apart from it “helps to pass certification tests”…
This is not the first time FAA/Manufacturer did that trade-off/hack, in the MD11 they used to call it LSAS 
http://www.md-11.org/md11/AFS%20Panel.pdf
https://www.wsj.com/articles/SB969325013164664251
For yaw/roll, having sort of “MCAS” was never a drama, except few cases:
https://en.wikipedia.org/wiki/Boeing_737_rudder_issues
I was under the impression that the MCAS system was introduced to make the type variant behave like the other 737’s thereby “saving” extra training.
It is just another “oh we let the computer fly the plane” rather than letting the pilots FLY the plane and feel how it reacts especially in these important phases of the flight.
A nice article on a blog I didn’t know, in french. It sums up the computer systems of the 737 first, but after it shows data of the lion air crash. Seems crédible…
https://lustublog.com/2019/03/14/mcas/
I learnt several things about the 1st one: the incriminated sensor has been changed the day before, the faulty return value, the fact that crew has first the idéa of using the flaps…
Wise words and analysis from Peter Lemme….
https://www.satcom.guru/2019/03/ethiopian-et302-similarities-to-lion.html
Interesting analysis. You would think a 22 degree AoA error would become apparent elsewhere if it was a software thing e.g. corruption of a memory location.
