Originally Posted by
overhill45
Question - how much altitude is lost when using manual trim wheel to crank back to the trim value in use when the flaps go up, Hal goes wild, to its max amount and pilot shuts of either or both primary and b/u switches immediately. Can it be done by ONE pilot or does it take two ?
Yes, I knows it is speed dependent as to required force to spin wheel ( nose up ) depending on which way failure is ..
Hopefully, the answer is zero. There will probably be some up and down on the altitude as the aircraft is stabilized, but if the pilots correctly apply the runaway stab procedure then there should be no significant loss of altitude. (From the data released to date, it appears the Lion Air 610 accident pilots did not accomplish this procedure, and the ET302 pilots did not accomplish the procedure correctly).
While the procedure itself can be accomplished by one pilot,
every procedure on the 737 (normal and non-normal) is designed to be accomplished as a crew to ensure that it is done correctly. If the stab is significantly out of trim when the electric trim is cutout, it will likely require the efforts of both pilots to use the manual trim to return the aircraft to a neutral trim state.