201–210 of 347 posts
Reading through the chronology in section 1.1, it feels like a movie where the aircraft is a malevolent entity that's trying to kill them. So if I were in the cockpit I'm sure it would've been some mix of fear and anger. My life's not in danger though, so I'm only left with the anger, on their behalf, knowing some greedy bunch of assholes were effectively that malevolent entity, whose will was expressed via the aircr…
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Another commenter pointed out that the captain is pulling back as hard as he possibly can on the yoke; releasing it to turn a trim wheel instead may have been just as deadly.
If my reading of the graphs is correct they are above Vmo for most of the episode. I'm surprised the flight surfaces weren't torn from their hinges.
Vne is where things start to get scary because it's usually based on flutter, which can catastrophically damage/destroy the aircraft in very short order.
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> And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe. I believe that's correct given that they had an Unreliable Airspeed Indicator warning (due to the malfunctioning AoA sensor), per the memory items on the UAI checklist. It makes the forces on the trim wheel much worse, which explains why they couldn't turn it, but it's the correct checklist response t…
> I believe that's correct given that they had an Unreliable Airspeed Indicator warning (due to the malfunctioning AoA sensor), per the memory items on the UAI checklist. The idea that a pilot would knowingly leave thrust at climb power while in modestly level flight at low altitude and expect not to overspeed is very strange to me, checklist or no checklist. I think they were too busy fighting the controls to worry…
>The left Indicated Airspeed increased, eventually reaching approximately 458 kts and the right Indicated Airspeed reached 500 kts at the end of the recording. The last recorded pressure altitude was 5,419 ft on the left and 8,399 ft on the right. How can the sensors record such different readings?
The reading from the pitot tubes (pressure sensors) for a particular airspeed varies with the sensors angle to the airstream so the airspeed value is adjusted based on the angle of attack (AoA). If the AoA sensor is on the fritz on one side the airspeed reading for that side changes. For redundancy, each pilot receives separate instrument readings from independent sensors. When the airspeed readings disagree a warnin…
The airspeed discrepancy has the same pattern: the left is reading low and also showing blips, where it equals the right reading, that also correspond to when the AofA indicators match.
All this would be consistent with the left AofA reading being used to correct the left static pressure reading by raising it at high angles of attack, and vice-versa for the right AofA vane and static port (this assumes there is a right static port used by the right pressure-driven instruments, an a left port for the left ones.)
Reading through the chronology in section 1.1, it feels like a movie where the aircraft is a malevolent entity that's trying to kill them. So if I were in the cockpit I'm sure it would've been some mix of fear and anger. My life's not in danger though, so I'm only left with the anger, on their behalf, knowing some greedy bunch of assholes were effectively that malevolent entity, whose will was expressed via the aircr…
Why is that getting downvoted? What the heck.
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It does not appear to be "precisely" the procedure, in that sufficient nose up trim was not selected by the yoke manual trim switch prior to pulling the trim cutouts. And then they did not work the mechanical trim wheel hard enough to reset the residual nose down trim. And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe. And, when they (against procedure)…
The thing is, it looks like they did try and use the manual trim switch to get the trim correct prior to pulling the breaker - they just didn't do it for quite long enough to fully correct for the misbehaving MCAS system's actions. If they hadn't I suspect the plane would've crashed several minutes earlier than it did. And remember, if they take more than a few seconds to consider whether the trim is correct before p…
> The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working. This is very damning to Boeing. It's precisely the procedure they prescribed and intended to mitigate possible MCAS caused trim runaway. In light of the fact that they put this in place as a justification for moving the engines forward without reclassif…
It does not appear to be "precisely" the procedure, in that sufficient nose up trim was not selected by the yoke manual trim switch prior to pulling the trim cutouts. And then they did not work the mechanical trim wheel hard enough to reset the residual nose down trim. And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe. And, when they (against procedure)…
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For comparatively trivial things like what to do when we get too much traffic on servers, engineers do “game day” testing. How does anyone expect pilots to run through these crazy scenarios and perform flawlessly unless they have done it in a simulator many times?
Um, they do? Endless simulator drills of various emergency scenarios is a large part of becoming a pilot and staying certified.
But a whole lot of social and political engineering was put into ensuring that simulator drills of emergency scenarios related to this system would not be part of any pilot's training.
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During otherwise normal flight conditions, the nose might unexpectedly pitch up. MCAS is designed to prevent that when AoA > somevalue to prevent stalling.
During normal flight conditions, the nose does not pitch up beyond the pilot's ability to control with the elevator, and the pilot doesn't fly especially close to the critical angle of attack. MCAS is for an unusual combination of conditions where both elevator and trim might be needed to reduce the angle of attack. An example would be if the pilot set a fairly high nose-up trim to maintain the slow speed of final ap…
This scenario seems it would apply to previous generation 737s as well. But for some reason, MCAS was required for the MAX 800.
Everything I have read so far indicates the MAX 800 has some 'pitch up on it's own' type problem that can lead to a stall. So while I'm sure it's possible to crash the plane in a variety of ways, none of that has to do with MCAS.