The Ship Model Forum

When I was in the Navy, the terms used for a missing or lost submarine were SUBMISS/SUBSUNK. These terms generated an operation to respond to the event. I doubt it has changed since I left.

We've heard that "broken arrow" is military code for a lost nuclear weapon. Is there a similar official phrase for a submarine that is lost/presumed lost and/or sunk? I know there's "on eternal patrol," but I'm looking for something more code-like.