That Visual Approach Slope Indicator (T-VASIS) was actually an Australian invention, as were "Black Boxes".
The crew got behind the "power curve", too low, too slow, and couldnt arrest their rate of descent established in a power-off approach. When power was applied, too late, the sink continued up to impact.
Managed to do exactly that about 40 years back, doing a "full load check" in a PA32-300 Cherokee 6 on a stinking hot summer day. Nearly creamed myself, instructor, and 5 guys who made up the full load. Did a glide approach, throttled back, speed ok, when suddenly sank like a rock.....full power hadnt quite arrested the sink when we touched down short of the runway (but luckily onto the bitumen of another intersecting runway short of the one aimed for), bounced, and settled down on the runway originally aimed for. If that other runway hadnt been there, it would have been nasty. So what happened? The instructor didnt see a prob,and didnt get a chance to intervene, we just suddenly sank. I put it down to 7 large bodies on board, full fuel, and 45 degree+ temperature.....and the glide approach. Always did approaches under power after that. The only flying in recent years has been in a 737-800 simulator when my wife buys me a bit of time to get rid of me briefly. Even there, power on approaches are the go. With a large, heavy, airliner, you dont get too many chances if you get it wrong.
