3 ms·

Basically the equivalent of a programmer saying "garbage in, garbage out". He's saying MCAS chews on the AoA sensor, and the AoA sensor was malfunctioning (the

Basically the equivalent of a programmer saying "garbage in, garbage out". He's saying MCAS chews on the AoA sensor, and the AoA sensor was malfunctioning (therefore shifting the blame to the user, who is responsible for maintenance). But failing to mention that Boeing had a role to play in those links of the chain too, first in using only one of the AoA sensors and not having the disagree alert work, and two in that there's a rumor that it's a Boeing problem causing the AoA sensors to become damaged in the first place.

jfk13 8y ago
Also, isn't there something about the MCAS system originally being certified to make only a fairly limited adjustment to the trim, and subsequently being modified (without re-certifying) to make a much greater adjustment? So it was designed and certified to be able to nudge the nose down a certain amount. Then they changed it to be able to force the nose down much more severely. And it did. Without being an expert, it sure sounds like the Boeing "safety system" is at fault here...
- fredthomsen 8y ago
  I read the same thing in an article but can't remember exactly where. Why manufacturers should be allowed to certify the safety of certain components of their own airplanes is beyond me.
  - cjbprime 8y ago
    I think the Seattle Times originally broke it: https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/faile... === After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees. That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment. “The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

jfk13 8y ago

Also, isn't there something about the MCAS system originally being certified to make only a fairly limited adjustment to the trim, and subsequently being modified (without re-certifying) to make a much greater adjustment? So it was designed and certified to be able to nudge the nose down a certain amount. Then they changed it to be able to force the nose down much more severely. And it did. Without being an expert, it sure sounds like the Boeing "safety system" is at fault here...

fredthomsen 8y ago
I read the same thing in an article but can't remember exactly where. Why manufacturers should be allowed to certify the safety of certain components of their own airplanes is beyond me.
- cjbprime 8y ago
  I think the Seattle Times originally broke it: https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/faile... === After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees. That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment. “The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”