Yes, burial at sea. See here, TBF/TBM Avenger units of World War 2 - Google Books I think this is one of a series of photograhs, IIRC, the rear turret had been covered with a tarp or large cloth. But, I don't remember where I had seen it.
AFAIK, yes only when an aircraft was damaged beyond repair. I don't find it disturbing at all. I don't think bodies were usually stored that far out at sea. So, the other option would be a canvas sack and a five inch shell. The airplane was where the man fought and died, I think it appropriate that he is buried at sea like that.