Originally Posted by
GordonR_Cape
I think your assertion contains several logical inconsistencies:
1. The momentary trim inputs may be an artifact of the FDR data sampling algorithm, or the crew stopped trying when the trim wheels didn't turn after a few seconds. We don't really know for sure, and IMO you can't build an argument on such evidence.
2. The recorded increase in the stabiliser ANU position may also be a data artifact, or backlash in the cables and pulleys, or the trim motor locking mechanism. There are a number of suggestions from other sources (including EASA), that what you describe is physically impossible at high airspeeds and aerodynamic loads.
3. Re-enabling the trim switches after runaway trim, is not documented in any procedure, so cannot count towards the certification process. They could re-write the procedures, but currently it seems to fail certification under those extreme conditions.
Edit: Reuters has an excellent article, citing some very knowledgeable sources:
http://www.reuters.com/article/us-et...-idUSKCN1RA0DP
https://
[/QUOTE]
www.reuters.com/article/us-ethiopia-airplane-regulator-insight/regulators-knew-before-crashes-that-737-max-trim-control-was-confusing-in-some-conditions-document-idUSKCN1RA0DP[/QUOTE]I would say that the majority of pilots who have been trained on the 737 (I have flown the Jurassic, old EFIS and NG series) see the "stab manual trim wheels" (located on either side of both pilots center pedestal),rotating, indicating that the use of the control column switches "are trimming the stab" (no autopilot engaged). Due to air loads and the fact that MCAS had activated, this lead the crew to believe that the STAB trim wasn't working properly (manually or electrically). Again, we are not privy to the CVR and all of the distractions the crew were facing at this crucial time, low to the ground.