I would assume that the U.S.S. Fitzgerald could "see" the dirty great container ship either visually or electronically with radar or other on board sensors. I don't really see how they can say that they were not aware of the container ship's presence, unless of course everyone on the bridge of the Fitzgerald was either fast asleep or completely incompetent. I can only assume that the Fitzgerald was under the impression that it had "right of way" but clearly the container ship either had other ideas or simply didn't see the Fitzgerald.