Possible it was hit on the way to the UN Building? People make mistakes when they are doing something extremely hazardous like this. A quick look at the gps and blam.
re: Qs about UN building and Gracie Mansion
UN is about 1.5 miles south of that spot and Gracie Mansion is a little over 1 mile north of that spot, so if either of those was a target in this the pilot did not have any aim at all..... I'm leaning toward an accident with a heart attack or stroke rendering the pilot unconscious, but what do I know??