We were doing what we do best - a lone wolf patrol in the far North Pacific. Things were looking tense in the world and the news that a Kuznetsov aircraft carrier battle group was heading for US shores was not good. It was known to contain a couple of Slava cruiser escorts, together with their Helix naval helicopters. A couple of Akula submarines were also rumoured to be in the area. You could bet they were out to the front of the carrier, screening to stop us getting close. Well it was our job to make sure this was no second Pearl Harbour.

We lowered the radio mast - we had just received a radio update. Hostilities had commenced. We were to engage the battle group immediately, with the aircraft carrier as a first priority.

We slowed to 2 knots for maximum stealth and made a depth of fifty feet, the crewmen crisp and disciplined as they confirmed my orders. Now with our tower just feet below the surface we started streaming the port towed sonar array. We would drag it 1200 feet behind the submarine as an underwater microphone. It was more receptive than the hull and bow mounted passive sonars and would give us the necessary coverage to our rear.

The Electronic Warfare Support Measures (ESM) mast broke the surface - it picks up radar signals from other vessels. A strong signal came from the south-east, identified by its frequency as a fishing vessel. No worries. From the west, presumably heading towards us and the US shores, came the powerful signals of the carrier and its Slava escorts. I could have used my own radar mast to give me an exact range and direction, but that would give my location away at once.

More worryingly there were airborne radar sweeping the surface of the sea too. These were the Helix anti-submarine helicopters. At this range from the surface battle group they had to be considered our main threat. Their radar could pick up any masts we put up above the surface. Their sonar could be dipped into the water and used in active search mode. They had nothing to fear - we had no anti-helicopter weapons. And they could use their sonar to cue their air dropped torpedoes and to guide in the still unlocated Akula (shark) submarines, who could glide in for a kill with no need for active signals of their own. Already the helicopters were using their sonobuoys to send strong pings through the water, listening for any echo. The signal was weak - we were far enough away to be safe for the moment. We registered the frequency in our minds - 15 KHz means helicopters.

We would stay near the surface long enough to get three fixes on the enemy ships' search radar. That would be enough to get the bearings right and a rough estimation of distance. Neither of us would have moved sufficiently in the single minute to have a really good fix, but it would do to the nearest 5000 yards. With the Harpoon anti-ship missile it was the bearing that we wanted most.

I gave the order to flood the three tubes I had loaded with Harpoons. The fourth I kept for a torpedo in case we were surprised by an enemy submarine. There was a loud hiss as the water flooded in and I equalised pressure. I checked the ESM mast again. The Helix helicopters were still too far away for my mast to give them a definite return on their radar.

No time like the present. The bow doors opened and I flicked up the covers on the three Harpoon fire buttons. From triangulation of the ESM bearings the battle group appeared to be some 45 miles away. The Harpoon should be good for fifty. I set the seekers to wide angle search and for them to go active after 18 miles. They should find their own way home.

The bow swung round to the west. The plotting board was still getting input from the ESM bearing. I pressed all three launch buttons in quick succession. After half a second or so the missiles fired from the front of the sub and streaked towards the surface, breaking out into the morning air. Skimming the waves the headed west towards their activation point.

Unlike torpedoes, Harpoons have no guidance wire to worry about. I shut the bow doors, dropped the ESM mast and ordered 12 knots, bearing 180, depth 350. The submarine pitched forward and down to the left. Firing the Harpoons is noisy and I knew that if the Helixes had sonar in the water they would be heading my way quickly. I used compressed air to evacuate the torpedo tubes and ordered all three to be reloaded with Harpoons. That would take eight minutes.

My aim was to get below the layer - the protective interface of cooler deep waters and warmer surface water. Sound has a propensity to bounce off the layer and it would offer a little protection against the persistent attention of the helicopters. The increased pressure would also allow me to go faster without cavitating - creating little pockets in the water behind my screws that had the effect of advertising my presence.

I should have moved much faster and further. As I slowed to check my sonar for the presence of enemy submarines I heard a loud ping through the water. I checked my sonar receiver for direction and strength. It was the pair of helicopters - the 15 KHz ping meant it was very unlikely to be anything else.

"Torpedo in the water!" We had been found. No worries about cavitation now. I ordered flank speed, 32 knots, and a depth of 450. I hoped the torpedoes wouldn't find us below the layer. We headed south as fast as possible. No luck - the torpedoes switched on their active search sonar. We were getting strong pings at 20 Khz, so we knew they were heading our way. "Torpedo in the water!" They had dropped a second one! Not good.

We were loading and firing counter-measures from the three inch tubes as quickly as we could. Deep decoys first, to try to shake the torpedoes off. Shallow jammers to hide us as we raced for the surface waters above the layer. Reference to the 20 KHz bearings on the enemy active sonar display meant we could keep the nearest torpedo off our flank as we tried to race out of its sonar window.

We dropped more counter-measures and went back into a dive, this time releasing decoys that would stay just below the surface as we went back under the layer. We levelled out at 400 feet, racing south just short of cavitation speed. "Explosion at bearing zero-eight-seven!" Both torpedoes had impacted a countermeasure very close to us. But not close enough. We dropped our speed to 20 knots and swung right to bearing 240 in case the pilots had got a fix on our heading.

So what happened to those Harpoons? Well, I fired three to overwhelm the battle group defences and it was a good job I did. The two Slavas got off five SAMs and knocked out two of the Harpoons before the last weapon hit. Unfortunately it didn't hit the Kuznetsov. The Harpoon's radar had picked out one of the Slavas patrolling out to the front and chose that as its target. Still - for three missiles it was a good result. The Slava was sinking.

"Torpedo in the water!" The helicopters had dropped more torpedoes. We increased speed to 24 knots and swung south again. This time, although we heard faint 20 KHz pings, they were not very close. Our crew held their collective breath, but the torpedoes had failed to acquire and were circling in active sonar search for our submarine.

This time we were going to learn our lesson. We stayed deep and fast for over 15 minutes leaving, as it were, the scene of the crime. Some broken glass, a muddy footprint perhaps, but no Topeka.

We slowed to 5 knots and headed above the layer. All was quiet. We were close to the trawler now, between him and the enemy carrier group. That was good - they would get noisy interference on our bearing, masking us. They were indications on the broadband passive sonar to the north, but listening in to the phones showed us these were whales.

We had escaped. The Slava was giving out 8 KHz pings to try to find us, but with no success. To the north the helicopters were still dipping their buoys, then moving off to try some of our escape routes.

We swung to the west, towards the battle group. God bless stand-off weapons. Keel depth 50, 2 knots. Nice and quiet. ESM mast up. The battle group was still steaming east, estimated at 17 knots. The fix wasn't perfect but it was good. As they were still coming towards us it would be a low deflection shot and the absence of neutral shipping meant that we could use the wide angle radar seeker to pretty much ensure a hit. The tubes were flooded and readied.

The missiles fired and burst through the surface. I had learnt my lesson. This time the ESM mast was down, the tube doors were closed and I was doing 25 knots southwards at 400 feet before you can remember what ADCAP stands for. Once again the helicopters closed in and started pinging, but at that range and depth we were well away by the time the first torpedo hit the water. It looked around in disappointment then described its lazy search pattern as we sped away.

Once again the Harpoons scored a Slava, overcoming the defensive systems. Now the Kuznetsov was alone on the surface, but the noise of the launches and our hasty exit was in danger of giving us away. Once we had secured ourselves a fair breathing space we slowed to first ten, then six knots in order to have a good look at the passive sonar.

Unlike active (pinging) sonar, passive sonar creates no emissions and is very stealthy. It listens in to other craft through a series of marine microphones attached to the hull of the submarine or towed behind it. As well as the trawler we were starting to get indications of submerged contacts racing towards us from the west. It appeared that the Akula subs were sacrificing stealth for speed in an attempt to get us before we could sink the carrier.

The above map plots known craft to their best fix from the plotting board. This fix isn't always very good. All initial bearing-only contacts are assumed to be at 10,000 yards and it takes a while to get accurate ranging. But this far into the mission it represents a good picture of the situation.

On the map our submarine is represented by the light blue circle. The yellow "E" contacts are from the ESM system and represents targets identified by their radar emissions. Nearest us is the Trawler (E2) while on the left we see the Kuznetsov (E1) and a dead Slava (E3). The two red "M" contacts are from merged data, in this case a combination of sonar sources, as these are the two Akula subs.

It was going to be a matter of time before we were found. We were clear for the moment, so we dived back under the layer and headed south while the three tubes loaded Harpoons. The moment they were loaded we slowed back to five knots and made a depth of fifty feet, heading 294. "Launch, Launch, Launch!"

It was too easy. Without the cruisers' protection two of the three missiles found their mark, splitting the Kuznetsov in half. To add insult to injury we surfaced, raised the radio mast and transmitted the mission success signals back to our fleet. Job done.