I fly B738 and often on NPA's using VNAVPTH. It's very good and inevitably pops us out of cloud with 2R 2W: assuming the NPA glide path matches the PAPI. I've just read the interim report of this accident. I assume they were also using VNAVPTH and that the glide path would intercept the RWY about the touchdown zone. The TCH is usually elevation + 50' in the LEGS page.
The report stays, as confirmed by CVR, that at MDA (550'-ish) there not visual but continued descending. The captain took over at 150' and a GA was initiated at 20'-ish. At no time did the EGPWS alarm sound as they did not enter the envelope.
This would suggest that they did not stuff the nose down and enter a hi-ROD and so trigger 'sink rate.' They impacted the water 300m from the threshold. This is 600m from the normal touchdown point.
My curiosity is how? If they were on profile at MDA, in trim, on speed etc via the automatics, and they did not trigger 'sink rate' how could they end up so short.
I see they did disconnect the automatics at minimums, and continued the descent manually. There was a slight reduction in attitude and a slight increase in speed; but could this have put them so short? The FD must have been screaming (silently) to raise the nose. Perhaps both pilots were searching outside. Either way, my thoughts about being in trim and thus on a correct glide path still stand. To be so short I'm surprised they did not get 'sink rate'.
Any thoughts?