Originally Posted by
Speed of Sound
So what procedure is in place to aid a pilot manually trimming a seriously out of trim stabiliser?
EASA among others seem to think that it is still a problem. Saying that a pilot shouldn’t allow the aircraft to get out of trim in the first place is hardly helpful to a pilot who finds that the manual trim wheel can barely be turned at high speed and increasingly lower altitude.
Yanrair is essentially correct. This aspect of the manual stab trim system has been there on the 707, 727, and the entire 737 line since inception, and it was apparently okay with the EASA and its predecessors. What changed? Well, for one thing airline training departments stopped teaching it, and general awareness of the issue was apparently lost along the way.
I've been on Boeing's most of my 30+ years in aviation, and I am very familiar with the trim system. Quite a few years back, I was actually taught the "roller coaster" technique. Somewhere along the way, the stab system in general, and runaway trim in particular, became less and less of a feature in our training syllabus. Despite the fact that runaway trim is a "memory" procedure, a pilot might see it once on initial checkout but it was not a regular feature of our normal recurrent training cycle (Stop and think about that for a moment.) In the early days of the MAX accident investigations, I was absolutely flabbergasted by the number of 737 pilots at my own airline who were unaware of many aspects of this trim system. To the extent that this was also the case at Lion Air and Ethiopian, then the pilots' reactions are more understandable.