Derfred, thanks again, to us non HGS equipped, this helps to understand why the HUD is a useful aid to safe flightpath management.
Vortex, sorry to have speculated about the use of the HGS without fully understanding the system, but according to the MAK interim report, there was a 12s APND trim input and we now know from Derfred that the HGS can be difficult to interpret in turbulence.
On the 737, the windshear escape manoeuvre, (after performing initial actions such as maximum thrust, 15deg pitch) recommends following useful guidance. On the HUD, the F/D (or guidance cue as it is known in theF/D guidance - because the F/D has a "windshear mode" which gives very HUD world) appears to dash all over the screen - as it responds immediately to every turbulent aircraft pitch and yaw - to the point where attempting to follow it appears to become an exercise in futility.
I said as much to the instructor after the event, having concluded already that I basically had no control over the aircraft using the HUD. He then asked the F/O what he thought of my efforts. The response was "extremely well handled". According to his PFD, I was flying the F/D very accurately, and the whole manoeuvre was very well flown
The RHS cannot use the HGS and the guidance is more sensitive than the PFD, so we have one pilot using one type of guidance system and the other pilot using a different one.
So, from your information regarding the HGS, is it not possible that a dual and opposing control input was the cause of the 12s nose down trim input, bearing in mind the crew must have been tired and somewhat stressed.
What would your views be on the cross cockpit co-ordination when both pilots are using different displays? The interim report does not mention whether the HUD was in use or not, but it would seem from the thread that it is SOP.
It also seems that the HUD/FGS requires a degree of currency, is it used for all approaches or just for LVOs?
The 737NG HUD is designed to be used in all phases of flight. It reduces the instrument scan rate required during manual flight and generally results in much more accurate manual flight - including a go-around or windshear escape.
In this case it didn't.
Thanks again for the informed comment.