It's in the original set of Standalone scenarios.
Just gave it another couple of tries. The first time, I was detected outside the kill zone and lost a sub before I could blink. Put this down to not having switched-off all the sub's sensors as I'd thought I had (didn't uncheck the manual control box) and started again.
This time, I sent a couple of subs into the kill zone, just below the layer and with no sensors on, avoiding cavitation. Again, one was speedily picked-up and attacked with a torpedo. Thankfully, it missed and, checking the type, I discovered that it was ineffective below 656'. Great, I thought, sending all subs as deep as possible. Unfortunately, just as I picked-up a Soviet SSN on passive sonar, I was attacked again, this time using a Silex missile, which has no depth restriction. This weapon was used to sink two of my subs and there seems no way to avoid detection.
As an experiment, I surfaced the third sub at a safe-ish distance so that I could at least see where the enemy were. In this way, I learned that radar has a longer range on the surface than it has at periscope depth. This revealed two ships, one of them a Kresta-class cruiser. Just for the hell of it, I submerged to periscope depth and tried to attack it, but stood no chance and, after evading a couple of missiles and torpedoes by tearing around at flank speed, was sunk before I could get into range. This, at least, seemed fair enough, as I'd only acted out of frustration and got what I deserved.
The question is, is there any way of keeping a submarine hidden against sonobuoys, sonar and ASW choppers, as I've yet to work one out?