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Another Boeing 737 Max-8 crash

Discussion in 'General' started by SPL170db, Mar 10, 2019.

  1. dieterly

    dieterly Well-Known Member

    With over 25 years of experience as an airline pilot I have never heard of takeoff/landing checklist having to be memorized, those are checklists that actually are read each time, or checked complete if the items are sensed, like on a 747-8 landing checklist.
     
    speedluvn, Gino230 and Steak Travis like this.
  2. jksoft

    jksoft Well-Known Member

    You would know better than I. I am just referring to my private pilot training, not professional or a jet. My instructor required them to be memorized.
    So on takeoff and landing, would the FO be reading off the steps while you perform the actions and flying the plane?
     
  3. baconologist

    baconologist Well-Known Member

    As the a/c get more complex and faster, the lists get much longer and start earlier. I wouldnt want to rely on memory for some thing much larger than a 172/Warrior
     
  4. Trunxgp1224

    Trunxgp1224 Well-Known Member

    As both a pilot and maintainer in the past, you memorize checklists out of habit and certainly work to review the emergency check lists as often as possible. But regardless of the situation you always pull out the checklist and read it.
     
  5. BigBird

    BigBird blah

    Seems like they were trying to read the manual on how to fly the thing, think they were past checklist since they didn't even know where to begin

    Sent from my smatrfone
     
  6. Trunxgp1224

    Trunxgp1224 Well-Known Member

    Never flown jetliners but my first instinct if I'm nose down and need to gain altitude is to give it throttle, check air speed, and pull up; checklist be damned I'm flying the plane first. In this boeing situation, would the system kick off if the pilots pulled back on the yoke or would the MCAS override the pilot input regardless of what the pilot did?
     
  7. HPPT

    HPPT !!!

    Check out the Seattle Times article a couple of pages back.
     
  8. Motofun352

    Motofun352 Well-Known Member

    Ya gotta love the video memes the news guys are showing. Looks like the planes are on a rocking horse cycling at a 1 hz cycle. I wonder what the real cyclic rate is.
     
  9. Trunxgp1224

    Trunxgp1224 Well-Known Member

    Well shit, if the system really gave MCAS unlimited authority then that's retarded. Again, I've never flow jet liners but in most cases of a power on stall simply relief of the yoke will bring the nose down, I see no need to allow a system that can put the tail into full stop to a nose down trajectory. but I don't think I got my question answered, or I missed it, if the pilot is pulling up and MCAS is commanding down, which direction does the elevator actually go?
     
  10. HPPT

    HPPT !!!

    I could be wrong but my understanding is that the MCAS pushes the nose down again after the pilots bring it back to level. So the cycle keeps repeating itself.
     
    BigBird likes this.
  11. Trunxgp1224

    Trunxgp1224 Well-Known Member

    That's what happened in the lion air crash, the article states that they had multiple rounds of resetting the switches, but it brings me back to what I was always taught; fly the plane. Screw resetting switches; apply power and pull up, if they had continuous pressure on the controls to climb would the MCAS override that command and push the nose down anyway is what I'm wondering.
     
  12. HPPT

    HPPT !!!

    It's my understanding that the system pushes the nose down when it senses a stall condition, regardless of what the pilots are doing, unless they disable it. I guess we'll have to wait for Gino in the pros for the definitive word.
     
  13. joec

    joec brace yourself

    Was the stall warning annunciator just not enough? Or were pilots just completely ignoring it?
     
  14. No matter what, if the computer-controlled safety systems react faster than a human pilot can react, that is a potential recipe for disaster. A checklist won't help.
     
  15. Gino230

    Gino230 Well-Known Member

    It’s not pushing the nose down. Its trimming down. It’s a very gradual increase in forward control column force. On Lion air flight, the captain was flying and he was trimming up every time the mcas trimmed down. Thus maintaining equilibrium. Then he handed the controls off to the FO, presumably so he could manage the situation, (or maybe they realized the FO had the accurate airspeed indicator.) The FO did not trim against the mcas. He allowed it to trim so far down that he was having a hard time holding the nose up. At the last second the captain took over again and stared trimming up but it was too late.

    Again, to allow the trim to run for more than a second or two (it takes 30 seconds of constant trimming to get that far nose down) is NOT FLYING THE AIRPLANE. More than a second or two of uncommanded trimming is a major red flag.

    Now, if the article in the Seattle Times is true, the fault in the system is that although it’s authority is limited, every time you trim against it, it’s authority is reset, thus it could get way out of trim due to the sensor failure. That is a bad design.

    All these automations showing the nose getting forced down are bullshit.
     
    ChemGuy likes this.
  16. Indeed. If the flight computer is reasserting control faster than you can, and fighting you for control, then a crash is the unfortunate result. It's a a loop that cannot be escaped.
     
  17. Monsterdood

    Monsterdood Well-Known Member

    The problem is also that at higher speeds in a full trim condition, there is not enough elevator authority to overcome the stabilizer trim authority. So there may be a point that you cannot pull back hard enough or far enough to overcome the nose down force created by the runaway trim command.

    And Boeing used to have the trim cutoff in the opposite direction (aft column cutoff switch) so the system would stop trimming if you were really fighting it. That safety feature was removed for some reason at some point. That is where Boeing stopped letting the pilot win in a conflict between aircraft controls and pilot input.

    Satcomguru is an ex Boeing engineer who has put up some relevant info and has been quoted by the Seattle Times amongst others.

    With the FBI involved now and subpoenas to some Boeing DERs, this will be all about the cert process and their safety processes.
     
  18. Gino230

    Gino230 Well-Known Member

    Also, as I’ve stated before, I don’t want to beat on these Lion Air pilots too hard, this was a very disorienting situation and one that’s not easily diagnosed. But you still need to fly pitch and power, and run the appropriate checklist. I’m guessing we will find they did not have very much “stick and rudder” time in their logbooks, without the autopilot engaged. That’s why these investigations take years- not 24 hours as the Facebook universe demands.
     
  19. dieterly

    dieterly Well-Known Member

    This is from the preliminary report about the Lion Air accident; at 400' IAS disagree, with the stick shaker activated, they determine the left PFD has the wrong information and FO takes over as Pilot Flying, then at some point the airplane starts to trimming nose down and the control column is too heavy for the FO to hold back, thats when they switch the STAM TRIM switches to CUT OUT (momentarily), but the problem comes back after the switch them back to NORMAL, then again the switches are moved to CUT OUT and they regain full control and they continue to Jakarta. After they land they write up problem so maintenance can have a look at it. I think the next day a new crew took the airplane and that’s when it crashed. The aircraft also had a history of Speed and Altitude flags,, Speed/Mach trim fail lights, Auto Throttle issues on take off etc.
     
  20. Gino230

    Gino230 Well-Known Member

    The column cutoff still works for speed trim and Mach trim. But not for MCAS for some reason.
     

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