It may become obvious that they did know "someone was there", but didn't take the proper evasive action. By the way, Ted, Warrant Officer is, or was, usually the rank of a helicopter pilot, at least before the Viet Nam conflict, during which anyone would take the seat when neccesary.
The initial report I read stated two noncoms were in the cabin with the Captain. You are correct, there were two pilots on board. And, a Warrant Officer does hold a commission.
Not that any of that appears to have helped in this case.
Best,
Ted
