Was there a problem with stalling on 737 jets before the 737 Max, if not then why is MCAS needed on the 737 Max 8.If it was a problem why did Boeing wait so long.

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    $\begingroup$ All airplanes stalls. Most airplanes only stalls when the pilot instructs it to do so. The problem of Max is, it could stall itself, slowly. MACS is added to correct itself from doing so. $\endgroup$ – user3528438 Apr 28 '19 at 16:32
  • $\begingroup$ @user3528438 How is that different than a 737NG? $\endgroup$ – Harper - Reinstate Monica Apr 28 '19 at 16:44
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    $\begingroup$ @Harper They didn't crash from a stall, they crashed when the MACS tries to correct a false stall, and it did happen across several minutes. $\endgroup$ – user3528438 Apr 29 '19 at 0:18
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    $\begingroup$ This question is marked as a duplicate of a question that was posed at a later date??? $\endgroup$ – Koyovis Feb 12 '20 at 23:11
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    $\begingroup$ @Firefighter1 no, that's not correct. you can post the link in a comment without flagging $\endgroup$ – Federico Feb 13 '20 at 6:54

Was there a problem with stalling on 737 jets before the 737 Max,

The flight characteristics, including high angle of attack operations, of the previous models of the 737 did not warrant the kind of action the MCAS system provides.

why is MCAS needed on the 737 Max 8

The Max 8 engines are physically bigger—69.4 inches fan diameter versus 61.0—heavier, mounted farther forward and higher than previously. This changed the thrust line and flight characteristics. MCAS is used to restore "normal" 737 flight characteristics.

See http://www.b737.org.uk/737maxdiffs.htm for details.

  • $\begingroup$ Would you agree with the phrase that was added to your answer without any reference? "In particular, the new engine cowlings added enough forward lifting area to affect the plane's handling at high pitch angles." $\endgroup$ – Koyovis Feb 12 '20 at 23:19
  • $\begingroup$ @Koyovis To the best of my knowledge, I didn't post this answer even though it's attributed to me. I say to the best of my knowledge because I am subject to some dementia, and I've learned I can't always trust my memory anymore. However, I've never flown any model of the 737 and really know nothing of it. My large aircraft were the 727-100 and 747-100/200. I looked at the link in the answer, and I'm as certain as I can be that I had never seen that web page before. I don't know what's going on. $\endgroup$ – Terry Feb 13 '20 at 0:06
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    $\begingroup$ @Jpe61 Please respect the original poster of the answer. I would never fundamentally change or add to an answer of another user here, but would post my own answer if I reckoned more details are required.. Now Terry's name and face is underneath some text that he never published.. $\endgroup$ – Koyovis Feb 13 '20 at 8:05
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    $\begingroup$ @Koyovis, sure thing, rolled back. I do not understand how this improves the answer though. The recently added edit by Guy should be removed too. $\endgroup$ – Jpe61 Feb 13 '20 at 8:10
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    $\begingroup$ @Jpe61 Agreed, did so. $\endgroup$ – Koyovis Feb 13 '20 at 8:13

Previous 737 models had acceptable stall characteristics.

The Max introduced new and larger engines. There was not enough room for them between the wing and the ground, so they were moved forwards further in front of the wing to make room for them to sit high enough and clear the ground. This affected the handling of the Max at high pitch angles.

But the intention was to introduce the Max without the need for significant pilot re-training and type re-certification, so the change in handling was unacceptable. MCAS - the Manoeuvring Augmentation Control System - was introduced to manage the aircraft handling at high pitch angles and avoid the need for pilot re-training.


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