but why did it decay again so high up that the rotors had completely stopped before it hit the pub roof? For me, this is the real question.......
There can't be many possibilities. The only two I can think of are a visual miscue (height judgement) but to my mind that's unlikely as I can't see anyone setting up an auto into a dark built up city block. Why would you when the completely unobstructed river is right next to it?
The other, far more likely is simply panic. Seeing nowhere to go, not visualising the river as a clear area and an automatic motor response to arrest the descent occurring by reflex in what looked like a hopeless situation.
It's what people do, I'm afraid.