PPRuNe Forums - View Single Post - Indonesian aircraft missing off Jakarta
View Single Post
Old 13th Nov 2018, 21:38
  #1124 (permalink)  
silverstrata
 
Join Date: Mar 2010
Location: L.A.
Age: 52
Posts: 556
[left]
Originally Posted by sgs233a View Post



From reading this thread and the Boeing alert, it seems that a big part of the issue is that the crew was not aware of MCAS. The writeup for STS "trimming the wrong way" may very well have been written by a captain that thoroughly understood STS and was aware of which way it should normally trim....but what he was seeing was the undocumented MCAS feature trimming .


Ok, I did not know the Max has a new stall assistance system. As mentioned before, the STS normally trims down after take off, so it would be operating in the same manner as the new stall system. So again the tech log entry about STS appears incorrect.

And why did Boeing incorportate a stall assistance system that trims, instead of using a stick pusher? This seems to go against the normal rules for flying. You fly the aircraft with the control column, not the trimmer.

A stick-pusher acts on the control columm, to increase speed, and withdraws its influence instantaneously to allow you to recover from the dive. A stall trimmer will trim you down, but leave that nose-down pressure on and impede your recovery from the dive.

A stick pusher is flying the control column, in the normal manner; while a stall trimmer is flying the trimmer. Is this how the new stall system works? I cannot find details on-line.

Silver

silverstrata is offline