I used to fly the B737-200 a very long time ago. I seem to remember that one exercise during flt sim refreshers/base checks involved trimming forward (to counter the effects of rising airspeed and thrust induced pitch-up) whilst accelerating, using G/A thrust, from an in-trim, S&L condition at very low airspeed and that during this manoeuvre the tailplane trim jack would stall due high aerodynamic loads generated by the elevator, thus preventing continued nose-down pitch trim operation (a feature of the actual aircraft). To counter this, forward stick pressure would be eased, thus reducing load on the trim jack and hence allowing nose-down trimming to be reapplied. Forward stick pressure would then be resumed to control pitch-up as the aircraft continued to accelerate and the process would have to be repeated a further two or three times, producing a “porpoising” effect, before normal trimming, in concert with forward stick pressure, could be continuously maintained.
Perhaps current and experienced B737 Classic/NG pilots would advise whether my distant memory of this phenomenon is correct and if so is it also a feature of the B737-800? If correct and applicable to the -800, perhaps this unfortunate crew’s finally attempted stall recovery was hampered and ultimately thwarted by a series of accelerated stalls associated with the “porpoising” manoeuvre? I would be very interested to hear the views of experienced B737 pilots on this matter.
PS. If this has been covered previously, please indulge me as I haven’t time for a detailed trawl through the 1660 posts to date.