Heres what we have been told over here regarding the issue - on all NGs not just the -800.
The auto throttle is linked to the captains Rad Alt - not the first officers even if the autopilot is running under command B ( f/o flying)
During normal operations on any given landing if the Captains rad alt reads less that 26ft AGL then the auto throttle retards to idle.
The idea being that the system assumes that you are in landing mode and have simply forgotten to disengage the auto throttle system.
We dont see this usually because SOP dictates that on normal landing with the exception of Auto land - we must disengage the auto throttle thru 50ft (above the 26ft trigger).
While I cannot explain the lack of cues this crew missed - ie airspeed - abnormal pitch indications - we know that many times "mode confusion" is the cause of many accidents.
It is not also abnormal on certain days to capture the path from above - the key however is that as a safety check in our (teal) system that if we are not stabilized by a 1000 AGL meaning on speed on target stable with engine spooled up then we go around -
If Turkish air had had this check - that last cross check of stable appch at 1000AGL and had the pilots adhered to it then maybe it might have saved lives - but thats alot of maybe's.
I know that this was not the only NG to have had this issue and it has occurred on at least two other occaisions - both times however the pilots caught the error and disengaged the autothrottle themselves and advanced thrust levers as necessary with no other deviation to flight path.
Regards
J