Originally Posted by
Ian W
---snipped--
Would you really let trim carry on monotonically trim down 2.5 units every 5secs and not switch it off? l can only assume that you would. It is really immaterial why the trim was operating it could be a now dead rodent chewing through an electric cable, you just want the trim to stop and two switches that have been there forever allow you to do that. I am sure that Boeing is aghast that their NNCs for trim runaway were being read in such a contracts lawyer fashion. Perhaps they should review the semantics of all memory items and NNCs/checklists and any training that reinforces those limiting semantics.
The Lion Air crews DID NOT KNOW how many units or even how long this goblin would trim. They didn't even have 10 seconds to observe the trim wheel amidst all the warning. To them, what happened to AC was exactly like what was reported/read in the pre-flight briefing: "STS running the wrong direction due to speed difference". As reported on the Lion Air's A-SHOR:
The conflicting data's [ALL INDICATORS were out of whack - previous flight at least the SIC's indicators were still valid, but not this one], perhaps observing the surrounding, rummaging through the QRH, communicating with the ATC, etc..., were all conspiring to overload their mental faculties and sensory perception. And, to top things off, they didn't have the luxury of having a dead head sitting on the jump seat helping to observe and analyze what's going on.
On the preliminary report, CAPT and/or FO of the previous flight apparently had failed to mention the stick-shaker condition and the NNC for runaway trim they'd performed to overcome what thought to be the STS trim going the wrong way. The last few facts are very much what makes the hole in the Swiss cheese lined up.