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posted by chromas on Tuesday April 30 2019, @11:00AM   Printer-friendly
from the it's-not-my-fault dept.

[CEO Dennis] Muilenburg said Boeing is making "steady progress" on a fix to the MCAS flight control system that's at the center of crash investigations in Ethiopia and Indonesia, but he stopped short of faulting the software's basic design.

"We've confirmed that it was designed for our standards, certified for our standards and we're confident in that process," he said. "It operated according to those design and certification standards. We haven't seen a technical slip or gap."

Preliminary reports from both crashes suggest that the MCAS system, which is designed to push the Max's nose down under certain flight conditions, was receiving erroneous data from faulty sensors. In both accidents, flight crews struggled unsuccessfully to take control as the airplanes continually dove just after takeoff.

In his remarks, Muilenburg said the incorrect data was a common link in a chain of events that led to both crashes. It's a link Boeing owns and that the software update will fix.

"[The update] will make the aircraft safer going forward," he said. "I'm confident with that change it will be one of the safest airplanes ever to fly."

Without elaborating Muilenburg also said that in some cases pilots did not "completely" follow the procedures that Boeing had outlined to prevent a crash in the case of a MCAS malfunction.


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  • (Score: 2) by choose another one on Wednesday May 01 2019, @10:45AM (1 child)

    by choose another one (515) Subscriber Badge on Wednesday May 01 2019, @10:45AM (#837158)

    MCAS doesn't "tie into" stick shaker because it is not an anit-stall system. Period.

    Yes the media have repeatedly painted it that way, because they can just about get their heads around that, but that doesn't make it true.

    Both MCAS and stall warning system operate at high AOA, but that is where the similarity ends - they don't even trigger at the same AOA threshold (MCAS can kick at lower AOA).

    MCAS is a (very) blunt tool way of altering the "feel" of the stick because on the MAX the stick can get lighter at high AOA due to lift from the engine nacelles (because they are very forward, which is because they are bigger and because bigger didn't fit under 737 wing). The stick "feel" is a certification requirement, the MAX couldn't meet that requirement without _something_ to make the stick heavier in certain corners of the flight envelope. In technical terms we are talking about the Cm-alpha curve - for a far better explanation than I could ever give see Bjorn's corner over at Leeham:

    https://leehamnews.com/2019/02/15/bjorns-corner-pitch-stability-part-10-wrap-up [leehamnews.com]

    (or read the entire series if you have time).

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  • (Score: 2) by The Shire on Wednesday May 01 2019, @08:06PM

    by The Shire (5824) on Wednesday May 01 2019, @08:06PM (#837514)

    Except in both instances the pilots were unable to override the MCAS nose down. That doesn't sound like a simple change to how the stick feels - thats a full on override.