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Old 03-17-2019, 04:40 PM
  #123  
ProppedUp
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Join Date: Oct 2010
Location: Globetrottin, Earth
Posts: 937
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Originally Posted by MikeeBooshay View Post
ProppedUP, thanks for posting that write up.

I do have a question for you. Noticing that the stick shaker is active most of the last half of the flight, how disconcerting would that be to a relatively inexperienced pilot? I would think that his training instinct is that " shaking stick = bad things, ie stall warning", would/could that have clouded his OODA loop somewhat, resulting in him doing things to correct a stall condition, but without recognizing that he didn't really have the condition present?

I am not a professional aviator, but have been around enough to know that it is drummed into a pilot from day one, stalls are bad OK, don't stall the plane? Seems like that there enough other data present and not considered by the pilot, we will never know, what he was thinking in the last few minutes.
In my experience the only time (except once, I'll explain later) the shaker goes of is in training and there are many other things you usually sense going wrong before it goes off. For example it gets real quiet (wind noise) which is not normal and is accompanied by low airspeed one may pick up on. Pitch changes. As you slow down your AOA increases assuming your in level or near level flight so your seat of the pants feel will tell you something ain't right because you are for a lack of a better way of describing it leaning back in your seat when you shouldn't be.

Also leading up to the stall the trim wheel is rolling quite a bit to trim pressure off as speed decreases which is also unusual. If the autopilot is on you will hear it run and run and run. If you were hand flying at some point you would have to ask yourself "gees I am putting in a lot of nose up trim?" You really get outside the box when you stall these things and personally I feel like there are many warnings before you get to the shaker going off. Again my only experience with this is in a sim with the autopilot on and auto throttles off. So the plane is trying to maintain altitude but you have turned off it's ability to add power.

I have had a shaker go off in another type aircraft in cruise flight. When it went off of course our eyes went straight to the instruments and cross checked in the blink of an eye. We realized quickly it was a false alarm and pulled the breaker. In a lot of aircraft (depending on the operation or company) they will put collars on breakers like stick shakers and stick pushers (737 doesn't have a pusher) so if the go off inadvertently you can easily locate the breaker and turn it off.

As far as what they were thinking I can't say. If the shaker goes off your first instinct would be to execute a stall recovery maneuver but I am sure about the time you started doing that and looking at your instruments you would realize that wasn't a true warning but a false alarm. While you can stall an airplane at any speed if you are relatively unloaded with plenty of speed your obviously not stalling or in danger of it. I would have had the breaker pulled which would have rid us of that annoyance. The next part went on for 6 minutes. I would say that with the shaker going off for 6 minutes that would be very distracting for anyone myself included while trying to fly. Who knows that FDR data may read what the computer was telling things to do. They may have pulled the breaker so it wasn't physically shaking but the computer was sending out the signal to. The CVR would pick it up though because it's loud.
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