3 ms·

The pickle switch is the thumb switch on the control yoke that controls the stabilizer pitch trim. Using it will pause, but not deactivate MCAS.

by throwaway201103 6y ago

WalterBright 6y ago
The pickle switch overrides the MCAS command, meaning it can be used to restore normal trim. Then, the trim system can be turned off via the console cutoff switches.
salawat 6y ago
Technically it (used to) reset the timer until MCAS activation to 5 seconds after it is released. So you'd have to repeatedly engage to get your stabilizer to where you want it and cut the power. They removed the ability for the electric switches to actuate while the FC was isolated from the stabilizer motor controls as part of the MAX design. With NG's you could flip one cutout switch which would isolate the computer, while leaving on the yoke switches. In MAX, flipping either one apparently cuts out both the computer and the switches.
- WalterBright 6y ago
  > So you'd have to repeatedly engage to get your stabilizer to where you want it and cut the power. No. The electric trim switches override the MCAS signal (in addition to resetting the timer). You can just hold them on until the trim is normal. This is indeed what both the LA and EA crews did repeatedly, they just did not then turn off the stab trim. This procedure is detailed in the Emergency Airworthiness Directive sent to all MAX pilots after the first crash. Boeing Emergency Airworthiness Directive "Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT." https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA...
  - salawat 6y ago
    My bad, misworded slightly, but yes, thanks Walter. Apologies for getting sloppy.

The pickle switch is the thumb switch on the control yoke that controls the stabilizer pitch trim. Using it will pause, but not deactivate MCAS.

WalterBright 6y ago

The pickle switch overrides the MCAS command, meaning it can be used to restore normal trim. Then, the trim system can be turned off via the console cutoff switches.

salawat 6y ago

Technically it (used to) reset the timer until MCAS activation to 5 seconds after it is released. So you'd have to repeatedly engage to get your stabilizer to where you want it and cut the power. They removed the ability for the electric switches to actuate while the FC was isolated from the stabilizer motor controls as part of the MAX design. With NG's you could flip one cutout switch which would isolate the computer, while leaving on the yoke switches. In MAX, flipping either one apparently cuts out both the computer and the switches.

WalterBright 6y ago
> So you'd have to repeatedly engage to get your stabilizer to where you want it and cut the power. No. The electric trim switches override the MCAS signal (in addition to resetting the timer). You can just hold them on until the trim is normal. This is indeed what both the LA and EA crews did repeatedly, they just did not then turn off the stab trim. This procedure is detailed in the Emergency Airworthiness Directive sent to all MAX pilots after the first crash. Boeing Emergency Airworthiness Directive "Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT." https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA...
- salawat 6y ago
  My bad, misworded slightly, but yes, thanks Walter. Apologies for getting sloppy.