Flap5
There's a lot of nonsense being talked about the crane. It's orientation and whether it was lit or not is frankly irrelevant. The pilot would have been SVFR which requires him to be clear of cloud and in sight of the surface. That means you stay over the river, avoiding buildings and bridges. I can only think that something distracted the pilot, like changing frequency, to cause him to lose his references.
That sums it up very well for me, based upon what we already know. There is no mystery or fault in any VFR (or SVFR) flight being below the height of nearby obstructions. But when VMC go bad...
...Single pilot operation can get very intense in bad weather, even for experienced pilots.
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The investigation will take its own good time, but I strongly suspect the conclusions will not venture far from that point.