7 ms·

> They must cut it at a moment where the stabilizer isn't grossly mistrimmed with respect to level flight, OR they may well need to re-engage it and race the MC

> They must cut it at a moment where the stabilizer isn't grossly mistrimmed with respect to level flight, OR they may well need to re-engage it and race the MCAS to get into a close-to-proper trim setup prior to cutting out the stabtrim and assuming manual trim control. All while keeping the plane in the air, reading the manual, and attempting not to lose composure knowing that the same thing has happened to another flight that lost all hands. I'm trying very hard to look at this objectively, but this is an extremely bad look for Boeing.

daddylonglegs 8y ago
> > They must cut it at a moment where the stabilizer isn't grossly mistrimmed with respect to level flight, OR they may well need to re-engage it and race the MCAS to get into a close-to-proper trim setup prior to cutting out the stabtrim and assuming manual trim control. > All while keeping the plane in the air, reading the manual, and attempting not to lose composure knowing that the same thing has happened to another flight that lost all hands. Additionally an angle of attack (AOA) sensor failure also triggers an unreliable airspeed warning so the pilots no longer trust their airspeed sensors or their AOA sensors while trying to judge pitch and speed. If they go too fast the control forces overpower them, if they go too slow they are more likely to stall. I don't think Boeing gamed out or tested in a simulator the human factors involved in an AOA failure at takeoff, particularly for pilots who - like the Lion Air pilots - are entirely ignorant of MCASes existence.
- Rooster61 8y ago
  I don't remember where I read it, but my understanding is that the MAX simulator does NOT simulate MCAS behavior. EDIT: Found it: https://www.reuters.com/article/us-ethiopia-airplane-simulator-exclusive/ethiopia-crash-captain-did-not-train-on-airlines-max-simulator-source-idUSKCN1R20WD https://www.reuters.com/article/us-ethiopia-airplane-simulat...
  - daddylonglegs 8y ago
    Thank you for that. Putting hundreds of aircraft into service before the simulators were available to airline pilots looks rather bad in hindsight. I would hope that Boeing internally had simulators for the MAX while they were testing it - along with a borrowed supply of pilots who were competent but had no inside information. Even if they didn't, a pencil and paper exercise might have been useful: 1. AOA sensor fails at takeoff (A), the pilots receive an unreliable airspeed warning and the stick shaker activates. The pilots now mistrust their sensors and want to keep their speed up and the nose down. 2. At about 1000 feet above ground the pilots level the aircraft, raise the flaps and start the unreliable airspeed checklist. MCAS starts trimming intermittently. 3. The pilot flying is having to pull further back on the stick and trim correctively while the crew work through their checklist. At this point the crew need to avoid any over-focus, task saturation or over-stimulus from the many warnings and indicators and ask themselves why the aircraft is trimming the way it is. They have a fairly narrow window of time in which to do this and then disable the trimming with the plane in a well trimmed state. (A) That this happened twice in relatively quick succession might be due to a common problem. Even if such a problem is found and fixed the AOA vanes and pitot tubes are delicate sensors sticking out of the nose of the aircraft; the system should be robust to failures in these sensors.
  - thatoneuser 8y ago
    I need to stop reading this story until the dust settles because I've read too many outrageous things about this whole deployment...
snuxoll 8y ago
> reading the manual Runaway stabilizer is a memory item, there should be no reading of the manual involved. Unfortunately the design of MCAS defeated the checklist of this particular memory item when in lower flight altitudes - which goes back to the argument that the 737 MAX never should have been given the same type rating as the older models.
- ams6110 8y ago
  At the very least it seems that some specific "differences training" on MCAS should have been included. I don't know at what point the differences are enough to require a new type designation.

daddylonglegs 8y ago

> > They must cut it at a moment where the stabilizer isn't grossly mistrimmed with respect to level flight, OR they may well need to re-engage it and race the MCAS to get into a close-to-proper trim setup prior to cutting out the stabtrim and assuming manual trim control. > All while keeping the plane in the air, reading the manual, and attempting not to lose composure knowing that the same thing has happened to another flight that lost all hands. Additionally an angle of attack (AOA) sensor failure also triggers an unreliable airspeed warning so the pilots no longer trust their airspeed sensors or their AOA sensors while trying to judge pitch and speed. If they go too fast the control forces overpower them, if they go too slow they are more likely to stall. I don't think Boeing gamed out or tested in a simulator the human factors involved in an AOA failure at takeoff, particularly for pilots who - like the Lion Air pilots - are entirely ignorant of MCASes existence.

Rooster61 8y ago
I don't remember where I read it, but my understanding is that the MAX simulator does NOT simulate MCAS behavior. EDIT: Found it: https://www.reuters.com/article/us-ethiopia-airplane-simulator-exclusive/ethiopia-crash-captain-did-not-train-on-airlines-max-simulator-source-idUSKCN1R20WD https://www.reuters.com/article/us-ethiopia-airplane-simulat...
- daddylonglegs 8y ago
  Thank you for that. Putting hundreds of aircraft into service before the simulators were available to airline pilots looks rather bad in hindsight. I would hope that Boeing internally had simulators for the MAX while they were testing it - along with a borrowed supply of pilots who were competent but had no inside information. Even if they didn't, a pencil and paper exercise might have been useful: 1. AOA sensor fails at takeoff (A), the pilots receive an unreliable airspeed warning and the stick shaker activates. The pilots now mistrust their sensors and want to keep their speed up and the nose down. 2. At about 1000 feet above ground the pilots level the aircraft, raise the flaps and start the unreliable airspeed checklist. MCAS starts trimming intermittently. 3. The pilot flying is having to pull further back on the stick and trim correctively while the crew work through their checklist. At this point the crew need to avoid any over-focus, task saturation or over-stimulus from the many warnings and indicators and ask themselves why the aircraft is trimming the way it is. They have a fairly narrow window of time in which to do this and then disable the trimming with the plane in a well trimmed state. (A) That this happened twice in relatively quick succession might be due to a common problem. Even if such a problem is found and fixed the AOA vanes and pitot tubes are delicate sensors sticking out of the nose of the aircraft; the system should be robust to failures in these sensors.
- thatoneuser 8y ago
  I need to stop reading this story until the dust settles because I've read too many outrageous things about this whole deployment...

snuxoll 8y ago

> reading the manual Runaway stabilizer is a memory item, there should be no reading of the manual involved. Unfortunately the design of MCAS defeated the checklist of this particular memory item when in lower flight altitudes - which goes back to the argument that the 737 MAX never should have been given the same type rating as the older models.

ams6110 8y ago
At the very least it seems that some specific "differences training" on MCAS should have been included. I don't know at what point the differences are enough to require a new type designation.