Originally Posted by
AvionicsWiz
If Dad reached across to help and went the wrong way with the trim, it would be:
1. Very obvious as backpressure on the yoke would increase
If the pilot was already pulling back with all the effort they could manage then an increase in nose down trim will not change the backpressure. It is already limited by pilot strength.
What happens is that the nose goes further down increasing airspeed and descent rate (as described in the NTSB report).