Today i was flying from CYYZ to EHAM in an KLM 747-400. I was on short final, and i set 1000ft in the autopilot. When the aircraft came to 1000ft, I reduced the speed to 160 knots (I read on an topic here that the landing speed of an 747 was 140 knots so i thought i was okay) after i did that, i lowered the gear and watched how it lowered. When i got back in the cockpit i checked everything before taking manual. I saw there that i forgot to set my flaps, they were still on 5°. I wanted to set them to full but in an blink of an eye i saw my plane on 400ft and rapidly desending. As an last try to survive, i applied full power and retracted the gear (go-around), but it wouldnt matter, i crashed into a feeld close to Schiphol.
My general question is, shouldnt i have got a approaching stall or a stall warning? If that had been the case, i could have performed a go around. And if the landing speed from a 747 is 140 knots, why was i stalling at 160kt?