The problem is, I think, that someone, something, somewhere, did detect the Crystal, but didn't act on it. The technology almost certainly worked right. It was likely the people that screwed everything up. The Crystal was probably on autopilot with no one (awake?) in the bridge and it would appear that the Fitzgerald was in the same state.

That said, for the US this is a pretty serious embarrassment, because it screams "not combat ready".

I am pretty sure that in a combat situation this collision would not have happened. It's the routine that is dangerous plus the mentioned "I am bigger" vs. "I am military" both assuming they have the right of passage.

Even discounting anything high tech, there's more than one person on watch, and the destroyer is much more nimble than a cargo ship. I imagine the postmortem will show a crazy breakdown across many processes.

Possibly not a great choice of words given that the article mentions that actual post-mortems are currently being performed.

What word do you suggest he use? If anything, I feel like 'postmortem' most commonly implies an after-action report - with the specific word 'autopsy' being used to describe, well, autopsies - at least in US english.

This is presumably a US English v English thing then, as post-mortem wouldn't be the term used here usually, and certainly not if someone had died (unless if was being performed on them). To someone from the US it would perhaps seem a little distasteful to describe the investigation as an 'autopsy' - hence my comment.

Oxford "British and World English" dictionary, post-mortem: "An analysis or discussion of an event held soon after it has occurred, especially in order to determine why it was a failure." https://en.oxforddictionaries.com/definition/post-mortem. Maybe not common in the UK, but I'd say it's perfectly correct word usage.

I grew up in USA Midwest, though I have been accused of a "southern" accent. "Postmortem" is completely idiomatic in this situation, but if you'd care to suggest a better term we'd all learn something.

Frankly I've been wondering if there wasn't some arrogance involved on the part of the destroyer's skipper.

It's kind of hard to detect evidence of arrogance when he was asleep.

I'll accept negligence, too.

It's negligent for a captain to ever sleep?