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posted by Fnord666 on Thursday December 27 2018, @08:28PM   Printer-friendly
from the man-versus-machine dept.

Arthur T Knackerbracket has found the following story:

Lion Air Flight 610, which took off from Indonesia on Oct. 29, should have never left the runway. On its previous flight, the aircraft gave incorrect speed and altitude readings.

But it's unclear whether the pilots were even aware that the plane had been malfunctioning. They took off at 6:20 a.m.

They immediately received the first signal that something was wrong: The control column started shaking loudly, warning that the plane was in danger of stalling and could crash.

The plane kept climbing, but the pilots could not figure out the correct altitude or airspeed, asking air traffic control for help. And two critical sensors registered different readings between the pilot and co-pilot.

Then the plane dropped over 700 feet, furthering the confusion inside the cockpit. "An aircraft dipping after takeoff is not normal. It's beyond abnormal. It's unacceptable," said Dennis Tajer, a pilot and spokesperson for the Allied Pilots Association.

Something alarming had happened: The aircraft's computer system had forced the plane's nose down. The pilots recovered from the drop, but air traffic control noted they were "experiencing a flight control problem."


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  • (Score: 0) by Anonymous Coward on Friday December 28 2018, @08:26PM

    by Anonymous Coward on Friday December 28 2018, @08:26PM (#779450)

    The final blame MUST be on the pilots, who could have disabled the autopilot system and for some reason choose not to do so.

    Why? Why should the pilots be blamed so much if it's Boeing who added a new feature and changed the behavior of some stuff and didn't inform the pilots about it or how to workaround things if the new stuff goes wrong.

    And why are you even modded informative? Disabling the autopilot does not disable the MCAS: https://www.flightglobal.com/news/articles/opinion-pilots-need-answers-on-737-max-safety-syste-453716/ [flightglobal.com]

    The 737’s Speed Trim System operates with the autopilot off

    a new feature, the Maneuvering Characteristics Augmentation System was added to the Max to enhance pitch characteristics while the aircraft is being manually flown at a high angle of attack with the flaps up.

    This is not small slow mechanicals-only controls plane. This is a mostly computer controlled plane.

    https://www.washingtonpost.com/business/economy/pilots-say-they-were-in-the-dark-about-boeings-737-max-safety-update/2018/11/28/10b2da14-f339-11e8-aeea-b85fd44449f5_story.html [washingtonpost.com]

    Previous iterations of 737s would have switched off key automatic control features when the pilot first pulled back the control column, a standard manual override feature in generations of airplanes. Investigators found that the final yank on the control column of Flight 610 registered almost 100 pounds of pressure, suggesting desperation in the cockpit as the plane plummeted.

    Maybe some Boeing pilots were informed of the new feature, but plenty of other Boeing pilots have claimed they weren't informed and they aren't happy about it.

    When you're flying at 450mph at 5000 feet and the plane nose dives you don't actually have that much time before it hits the ground.

    5000 feet / 150mph = 22 seconds. You don't have the luxury of hours to figure out which undocumented workaround to an undocumented feature that's failing works.

    One common approach is to prioritize keeping the plane airborne (and higher) then troubleshoot. You can't do much troubleshooting if you hit the ground first.

    But when trying to pull the plane up doesn't work reliably, you could start turning stuff off and/or you might assume wrongly (since Boeing didn't tell you) that it's still a normal 737 and a confounding issue is the manual override isn't working so well and you need to pull harder to get it to work reliably.

    So would average pilots not knowing about the MCAS feature have been able to have saved the plane? Because if Boeing has started making planes that only top pilots can fly safely perhaps more people should actually resort to flying on Scarebuses...