Yep Apparently the main problem seems to be the fact there is a single point of failure (a single AoA sensor) and it could be resolved by having multiple sensors. Not that some sort of new automation is occurring than before.
Having multiple sensors doesn't always help, as failures are correlated. For example, there was an Airbus A321 that had 2 of its 3 sensors get stuck in the same position due to icing.[1] The computer thought that the one working sensor was malfunctioning and disregarded it. It then engaged stall protection, dipping the nose and causing the plane to dive at 4,000ft per minute.
> The captain continued to hold “more than 50%” rearward stick in stable flight for a period, but with help from technicians on the ground, the crew was able to reconfigure the automation into the aircraft’s alternate control law, rather than its normal “direct” law. The action removed the alpha-protection checks and canceled the nose-down input. The aircraft then continued to its destination.
These failure modes tend to happen more with Airbus planes because their flight control systems default to overriding human input if the computer deems it unsafe. Boeing's flight computers will give more resistance in the controls, but they mostly won't prevent the pilot from doing what they want to do. The exceptions (such as auto-trim and stall prevention) can be disabled with by flipping a couple of switches.
"The automatic trim we described last week has a name, MCAS, or Maneuvering Characteristics Automation System.
It’s unique to the MAX because the 737 MAX no longer has the docile pitch characteristics of the 737NG at high Angles Of Attack (AOA).
This is caused by the larger engine nacelles covering the higher bypass LEAP-1B engines."
Boeing only told pilots MCAS existed following the Lion crash, almost 18 months after the plane entered service
dmix|7 years ago
ggreer|7 years ago
Having multiple sensors doesn't always help, as failures are correlated. For example, there was an Airbus A321 that had 2 of its 3 sensors get stuck in the same position due to icing.[1] The computer thought that the one working sensor was malfunctioning and disregarded it. It then engaged stall protection, dipping the nose and causing the plane to dive at 4,000ft per minute.
> The captain continued to hold “more than 50%” rearward stick in stable flight for a period, but with help from technicians on the ground, the crew was able to reconfigure the automation into the aircraft’s alternate control law, rather than its normal “direct” law. The action removed the alpha-protection checks and canceled the nose-down input. The aircraft then continued to its destination.
These failure modes tend to happen more with Airbus planes because their flight control systems default to overriding human input if the computer deems it unsafe. Boeing's flight computers will give more resistance in the controls, but they mostly won't prevent the pilot from doing what they want to do. The exceptions (such as auto-trim and stall prevention) can be disabled with by flipping a couple of switches.
1. https://aviationweek.com/commercial-aviation/german-investig...
youngtaff|7 years ago
This is caused by the larger engine nacelles covering the higher bypass LEAP-1B engines."
Boeing only told pilots MCAS existed following the Lion crash, almost 18 months after the plane entered service
https://leehamnews.com/2018/11/14/boeings-automatic-trim-for...