Stories
Slash Boxes
Comments

SoylentNews is people

posted by martyb on Tuesday April 09 2019, @11:03AM   Printer-friendly
from the pulled-the-handbrake-as-hard-as-I-could dept.

A 2018 FAA (Federal Aviation Administration directive advised pilots to handle MCAS (Maneuvering Characteristics Augmentation System) failure by disabling electric control of stabilizer trim using a pair of cutout switches. Pilots would then need to use a hand crank to move the stabilizer back to the desired position. It's noted that previous 737 models had separate switches to disable autopilot and electric stabilizer control, but the 737 MAX lacked this distinction.

Avionics engineer Peter Lemme explains how aerodynamic forces acting on the stabilizer and elevator in a nose-down situation would oppose pilots' attempts to correct the trim using their manual control.

A 1982 Boeing 737-200 Pilot Training Manual acknowledges this possibility, describing a series of maneuvers which can be used to relieve force on the controls and allow incremental correction of trim. However, it's suggested that the Ethiopian Airline plane had already gained too much speed and lost too much altitude for such a maneuver to be possible.

https://www.moonofalabama.org/2019/04/ethiopian-airline-crash-boeing-and-faa-advice-to-737-max-pilots-was-insufficient-and-flawed.html
https://www.satcom.guru/2019/04/stabilizer-trim-loads-and-range.html


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 0) by Anonymous Coward on Tuesday April 09 2019, @06:06PM (2 children)

    by Anonymous Coward on Tuesday April 09 2019, @06:06PM (#826958)
    But he demonstrated the solution in a simulator, with no aerodynamic forces - and then it took two to spin the wheels. In Ethiopia one pilot was pulling on the stick as hard as he could. By the way, these wheels are not very responsive, and until you roll them back close to zero, your a/c is still going down.
  • (Score: 0) by Anonymous Coward on Tuesday April 09 2019, @06:27PM

    by Anonymous Coward on Tuesday April 09 2019, @06:27PM (#826978)

    With the next safety directive Boeing should give them a broomstick. Then they can jam it between the control column and front panel while both pilots crank on the wheel.

  • (Score: 2) by pipedwho on Tuesday April 09 2019, @10:26PM

    by pipedwho (2032) on Tuesday April 09 2019, @10:26PM (#827142)

    Who cares about the air conditioning when the plane is about to crash?