Although the AIS transponder was turned off - the vessel would still have appeared on radar. The cargo vessel's system wouldn't have had the same amount of information for anticollision calculations, but still would have been able to detect it as an obstacle and would have flagged it to anybody on the bridge who was paying attention.

Plenty of ships go to sea without transponders on, such as large fishing vessels that don't want to give away where the good spots are.

Large fishing vessels turn on their AIS when crossing shipping lanes. Also, the whole point of modern military naval architecture is to reduce radar cross-section. Sure these boats can be seen from up close, but we can't assume that decades-old cargo ships are outfitted with the latest radar tech either.

My point was that AIS is not an anticollision mechanism and shouldn't be relied upon. It's also often wrongly configured or just broken.

The Royal Navy advertise their 8500ton Destroyer as having the radar cross section of a small fishing vessel: https://navynews.co.uk/archive/news/item/3951

I'm not sure what the weather conditions were like, but even in marginal conditions, they'll have been picked up on radar.

Even a consumer grade radar would be able to spot a 9,000 ton vessel from a thousand yards away no matter how "stealthy" it is, and they got closer than that.

Turning on transponders across the entire fleet is not a proportional response here. There are lots of military vessels out there and 99.99% of the time they don't crash into cargo ships. A lot of things went completely sideways for this to happen, and there are reasonable failsafes that can be enacted to prevent it in the future.

If they did that, then the second a war started all of our surface Navy would be wiped out in a first strike.

Considering the size of the US navy, around 430 ships, that's extremely unlikely. There's not enough submarines in the world to sneak attack them all at once.

No one would use submarines for the first strike in a major war unless it was to launch nuclear warheads from an unpredictable location. It would take months for them to get into position, even if the attacker had that many subs and it would reveal sub locations at the start of the conflict.

Hitting a ship with a missile is hard because they're usually out of land based radar range but if they all had their transponders on, it would be so much easier, especially since medium and long range missiles are getting increasingly more advanced. I wouldn't be surprised if state of the art recon satellites could pick up a cluster of transponders in a carrier battle group and use that data for targeting. If all an enemy did was take out our aircraft carriers, it would cripple our force projection outside of stationary military bases (which would all be hit in a first strike) and turn the navy into glorified mobile silos. The element of surprise is often the only deciding factor in skirmishes and battles between equal forces so it is paramount that giant, slow, and vulnerable fortresses don't broadcast their position.

Nukes don't work very well on ships much to the dismay of military planners.

There's a new generation of ballistic missile which might work, but they're extremely expensive, have limited range, and are rare. This idea of sinking the entire US fleet in one strike is utterly absurd.

Whereas, on the current footing, all it will take is a bunch of 12-knot cargo ships on autopilot to take them out. Either the captain and OOD should both be court-martialed out, or USA Navy needs to go back to the drawing board.

Yes, because once a decade one of our 400 naval ships has a survivable collision, we should turn AIS on full time.

[EDIT:] I didn't suggest that, but Lieutenant Commander Michael Kiser, USN does suggest that AIS be used in shipping lanes:

https://blog.usni.org/posts/2017/06/21/three-changes-the-nav...

Also, there are 274 ships in USN.

Also, this cargo ship did not intend to collide with the navy ship. In wartime, we can't make that assumption.

A single submarine loss (the Thresher accident) was enough to prompt the US Navy to institute the SUBSAFE program, possibly the single most successful safety program in history.

Considering that US armed forces are at war (or police action or whatever it's called) almost all the time since WWII it's likely we'll never know ;)

But even then they certainly don't want to make it simple to trace their complete deployments.