
Lion Air 737 MAX crew had seconds to react, Boeing simulation finds - okket
https://arstechnica.com/information-technology/2019/03/simulations-show-lion-air-737-crew-had-little-time-to-prevent-disaster/#p3
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cmurf
This article cites its source as:
[https://www.nytimes.com/2019/03/25/business/boeing-
simulatio...](https://www.nytimes.com/2019/03/25/business/boeing-simulation-
error.html)

Many questions are still unanswered including the catch all "does this
particular variety of MCAS upset look like runaway trim to some pilots, most
pilots, or all pilots?"

The 40 seconds part is something of a theoretical construction that just means
if you're surprised enough that you only try to fight the plane with yoke
elevator control alone (unlikely in my pilot, but not 737 pilot, estimation),
you've got merely 40 seconds and that very well could induce panic.

Central to reacting to an emergency is stabilizing the plane enough to buy
time, hopefully indefinitely, but even if you've bought 5 minutes that's OK to
move on to rational troubleshooting including preparing for an emergency
landing. If you don't ever get it stabilized, panic might set in. Even a
stable approach to an ocean ditching is better than an uncommanded nose dive,
because you know one could end well and the other won't.

~~~
cjbprime
> The 40 seconds part is something of a theoretical construction that just
> means if you're surprised enough that you only try to fight the plane with
> yoke elevator control alone (unlikely in my pilot, but not 737 pilot,
> estimation), you've got merely 40 seconds and that very well could induce
> panic.

So it's like "you only have 4 seconds to turn your car before it leaves the
road, if you don't use the steering wheel"?

The trim control is right there on the control column, it's a fundamental
control! Positing that the plane will descend and the yoke will get
progressively heavier without the pilot attempting trim control is ridiculous.

~~~
cmurf
It's an example of the magnitude of the defect and the urgency it cause. It is
not advocating a course of action. The source article directly points out that
using trim toggle would extend the time beyond 40 seconds.

Steering wheel is not analogous to a trim toggle, but rather the yoke. There's
no appropriate analog for trim on a car.

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cjbprime
I don't understand the 40 seconds idea at all. It seems like you can maintain
control of the aircraft indefinitely as long as you use the trim switches on
the control column to counter the MCAS movement while you diagnose the issue
and eventually disable the trim motor.

A claim that they had only 40 seconds to react can't also be true. It's one or
the other.

