PPRuNe Forums - View Single Post - NYT: How Boeing’s Responsibility in a Deadly Crash ‘Got Buried’
Old 24th Jan 2020, 17:09
  #102 (permalink)  
MechEngr
 
Join Date: Oct 2019
Location: USA
Posts: 134
Originally Posted by Semreh View Post
@MechEngr



Does that mean continuous functions have no meaning?

If you can understand the concept of an expected duration of a process, you can talk meaningfully about the process being continuous if it is not interrupted within the expected duration, or continual if it is interrupted a number of times within the expected duration. If we talk about a 'runaway stabiliser', it would be expected to continue until it reached the end-stops unless a manual cut-out is performed. If a stabiliser movement ceases without manual input, then restarts without manual input later, one can talk about an interruption. If the stabiliser moves in a particular direction, stops, then continues to move again several times, then it is moving continually.

Obviously, but unhelpfully, in the limit, when time goes towards infinity, all processes can be expected to terminate at some point, so yes, in the perspective of unlimited time, no process is continuous. If you limit, or focus your view on a finite subset of time, then a process can be said to be continuous over that segment if there are no discontinuities/interruptions.

I hope that clarifies things sufficiently for you.
The trigger for MCAS to resume is that a pilot made a trim input. Otherwise it was a one-shot. So it only restarted in response to manual input. And it moved continuously over that finite subset interval of time. It did not change speed or direction.

Awaiting a CVR transcript where the pilots are discussing continuous vs continual and that because it was continual, that the 60+ pounds of force required to hold the nose up required no trim to offset it.
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