US pilots have reported issues with new Boeing jet
9 replies, posted
https://apnews.com/0cd5389261f34b01a7cbdb1a12421e27
Airline pilots on at least two flights have reported that an automated system seemed to cause their Boeing planes to tilt down suddenly, the same problem suspected of contributing
to a deadly crash in Indonesia. The pilots said that soon after engaging the autopilot on Boeing 737 Max 8 planes, the nose tilted down sharply. In both cases, they recovered quickly
after disconnecting the autopilot.
The Max 8 is the same plane at the center of a growing global ban by more than 40 countries following a second fatal crash, this time in Ethiopia, in less than five months. In the U.S.,
however, the Federal Aviation Administration and airlines continued to permit the planes to fly.
The pilot reports were filedlast year in a data base compiled by NASA. They are voluntary safety reports and do not publicly reveal the names of pilots, the airlines or the location of the
incidents. It was unclear whether the accounts led to any actions by the FAA or the pilots’ airlines.
In one report, an airline captain said that immediately after putting the plane on autopilot, the co-pilot called out “Descending,” followed by an audio cockpit warning, “Don’t sink, don’t
sink!” The captain immediately disconnected the autopilot and resumed climbing.
So this has been known for at least a year then and nothing was probably done about it? Boeing stock might just crash harder than bitcoin.
A bit of light investigation into the crashes and it's pretty apparent that Boeing is responsible for omitting vital information about the MCAS (Anti-stall) system. Their 737Max was sold as needing no simulation time for previous 737 pilots, despite the fact it had new undocumented MCAS nose dive behaviour and did not inform any of the pilots of it's existence until AFTER the first crash.
MCAS sounds like a sensible solution, plane should try to automatically dive out of a stall, but it appears it overrides pilot behaviour. To disable it you have to know how to override the tilt controls, for a system they were not taught about.
On top of all this, the new 737Max engines and their placement on the wing have a tendency to pitch up in a high AoA, triggering the MCAS system and automatically pulling the plane into a nose-dive (which is why it was added in the first place). Not to mention the MCAS system is dependant on just one AoA sensor. There are two AoA sensors on the plane, but the computer only uses one to decide to nose down.
Ultimately, one failure point (one AoA sensor reading) and not informing pilots on how to counter-act an automated nose dive is just a recipe for disaster.
http://www.b737.org.uk/mcas.htm
https://files.facepunch.com/forum/upload/703/c3d1c950-e45c-46cb-a912-dad74ba9d0b0/image.png
I heard on the news a few minutes ago that 738M8 flights are halted everywhere except north america. Why the hell are they still flying them?
This is why
https://files.facepunch.com/forum/upload/229156/28dceb21-6610-48db-80ef-0728da762397/image.png
Though if the FAA already issued directives on training after the last accident and airlines followed through, their might not be a need to.
The article says that in a NASA report (voluntary safety report from a pilot) that a crew reported the nose down occured after the autopilot was engaged, meaning MCAS couldn't be the issue since it only comes on when autopilot is off. That's not to say that the system is working properly and disengaging when it should, or that all crews know exactly how this system works, but there's a good chance that something else is going wrong here.
I think the issue might be not in the executive part (MCAS, any additional logic running during autopilot) but in the measurement/sensing part (something about sensor processing - e.g. the logic which determines which one of two AoA sensors to be used, the logic that calculates AoA based on other data and so on). It's reasonable to assume that algorithms behind MCAS are well tested and understood by the engineers that no additional instructions were deemed neccessary, but there's always a possibility that there was an oversight and something was missed about behavior of system as a whole.
man and they're pushing spec flowdown so hard through NADCAP right now
Money over safety
I really dislike Boeing. They make dumb engineering decisions and are just always on the hunt for more money over safety. I hate their culture and business practices. They are incredibly shady. They can't deliver on promises on time or without problems, a lot of safety issues, quality control issues, you name it. They will do absolutely everything in their power to avoid actually admitting any kind of fault. Even then, when the pressure is too much and they are caught red handed, they pretend to care just long enough for them to sort of do something about the problem, until the next problem slaps them in the face.
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