levitate
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So it's pretty clear that it was the lack of spatial awareness was the reason they crashed .
The video above probably was the exact same situation. If u can't see the ground or anything that would show u that u are still leveled with the ground (top of clouds) then you can completely lose track of up and down. I'm pretty sure after he told the tower he was going to raise up over the clouds that he had no idea which way up was.
still could be mechanical... early reports by folks on the ground says the copter was sputtering before crashing