Many thanks for this finding
At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA
decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the
left AOA value reached 74.5° in 3⁄4 seconds while the right AOA reached a maximum value of 15.3°.
At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First-
Officer confirmed stab trim cut-out.
At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied
that the trim was not working and asked if he could try it manually. The Captain told him to try. At
05:41:54, the First-Officer replied that it is not working.
At 05:42:54, both pilots called out “left alpha vane”.
At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,400 2 ft, two
momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in
the ANU direction from 2.1 units to 2.3 units.
At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic
trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in
approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft
column force was applied, but the nose down pitch continues, eventually reaching 40° nose down.
The stabilizer position varied between 1.1 and 0.8 units for the remainder of the recording.
And this is just the key points. The details fully confirm the "scary place" scenario that many here have speculated. Sorry Boeing, this is really not just two switches to hit in quiet cockpit.
The STAB TRIM PRI cutout switch and the STAB TRIM B/U cutout switch are located on the control
stand. If either switch is positioned to CUTOUT, both the autopilot and main electric trim inputs are
disconnected from the stabilizer trim motor.
Last edited by PixelFlight
on Thu Apr 04, 2019 4:50 pm, edited 2 times in total.