Dangerous Ground

by Larry Bond

  * * * *

  Cold Welcome

  May 23, 2005

  Barents Sea, Southwest of Novaya Zemlya

  The next morning Jerry had the six to twelve watch in control. He and Tom Holtzmann arrived punctually at 0545, after their pre-watch tour through the boat, to begin the turnover with Lenny Berg. The relieving process always took some time, so officers were expected to show up at least fifteen minutes before their appointed watch.

  Unlike the surface navy, which had four-hour watches followed by eight hours off, the submarine force used a more abusive six hours on, twelve hours off watch rotation. After six straight hours on watch, the brain turns to Tapioca pudding and all one wants is to be relieved on time. Usually, Jerry was paired with another officer who was the same rank or senior to him. But due to his aggressive qualification schedule, Jerry sometimes found himself standing watch with Ensign Holtzmann. Although Tom was junior to him in rank, he had more experience, and was formally qualified to be an OOD.

  This meant he controlled the sub’s movements and actions during routine operations, and was responsible for three-quarters of a billion dollars of taxpayers’ money and the 137 souls aboard. If the boat went to General Quarters or some other special evolution, then the Captain would take over. Even if the Captain walked into the control room, Holtzmann would continue to run things, as long as Hardy was satisfied that he was doing a good job.

  As the Junior Officer of the Deck, Jerry was learning on the job, backing up his book studies with on-watch time and training under a qualified officer. Eventually, he’d go before a board of Memphis’ officers. They’d question him within an inch of his sanity, and if he satisfied them, he’d be a qualified OOD.

  There was no Junior OOD on the earlier midnight to six watch, so Jerry listened as Tom relieved a very sleepy Lenny Berg. Lenny showed Holtzmann their progress on the chart, reviewed the status of the ship’s reactor and engineering plant, and warned him about anything coming up in the next six hours. Some of the information was repetitive, as they had just talked to the offgoing Engineer Officer of the Watch, but a little redundancy is preferred over ignorance. After a few brief questions, Tom relieved Lenny and announced the turnover formally to the new watch section.

  Fifteen minutes into what Jerry had expected to be a quiet transit watch, the loudspeaker announced. “Conn, sonar. New contact bearing three zero zero. Designate new contact sierra seven six.”

  “Sonar, conn aye,” replied Holtzmann as he and Jerry clustered around the sonar console in control. The console had only a single display, but it could repeat whatever was on the eight displays the sonarmen were looking at.

  “Look,” said Tom Holtzmann. “Can you see what it is?” He stepped to one side.

  Jerry studied the computer screen, called a “waterfall display” because the older information “fell” toward the bottom of the screen as new data showed up at the top. The video display showed the sounds picked up by Memphis’ passive sonars, some of the most sensitive acoustic instruments ever built. The main passive array was a fifteen-foot sphere mounted at the bow with over twelve hundred transducers. It could also transmit powerful pulses into the water when the sonar went active. Memphis also had groups of passive hydrophones mounted along the forward part of her hull, and the most sensitive of all were the two lines of hydrophones towed behind her at the end of half-mile-long cables.

  All the sounds they picked up were collected and displayed as bright green lines or wide spots on a ten-inch by ten-inch video screen. Engineers had learned long ago that humans have a keener sense of sight than hearing and had modified sonar systems to take advantage of this natural fact. The louder the signal, the brighter the spot.

  Holtzmann had selected a broadband display that was divided into three separate bands. The top one displayed only a couple of minutes’ worth of data, but it was updated much more rapidly than the other two that showed more information. Every few seconds, a new line of data was added at the top, pushing the older lines down.

  A dim series of spots could be clearly seen on the topmost band, while it had just appeared on the middle one below. The displayed noise was fuzzy and wide, like the line left by a felt-tip pen on damp paper. A ship, especially a noisy one, would appear as a sharper, brighter set of lines because a ship has many different pieces of machinery, all making noise. This noise-maker was much more limited, weaker.

  The next spot appeared on the left side of the display, now bearing three one zero degrees, to the northwest. That meant it lay to port and behind them. As Jerry watched, a new spot appeared, and seconds later, another. The spots didn’t change in brightness, but the line that they drew was angling sharply to the right. That was important. Whatever it was had a high bearing rate, which meant it was fast and close.

  “What do you think it is, Mr. Mitchell?” Holtzmann asked.

  The bearing rate was the key. The only thing that moved that fast was an aircraft and the only aircraft in this neck of the woods were Russian ASW planes. “A Bear or May patrol aircraft.” He tried to sound confident. “It’s close, too.”

  As if on cue, the loudspeaker squawked back to life. “Conn, sonar. Sierra seven six now bears three one five degrees, drawing rapidly to the right. Contact is classified as a Bear Foxtrot.”

  “Good guess, sir. Now tell me how they know it’s a Bear?” Holtzmann inquired as he reached up and changed the display to one that showed narrowband data.

  Jerry smiled as he admitted his ignorance. “I know it has something to do with the type of engines, but other than that I haven’t a clue of what I’m looking at here.”

  Narrowband sensors look for acoustic noise sources that are tightly confined within a very small frequency range. This kind of noise is produced by machinery that operates in a very regular and repetitive manner—like an aircraft’s engines. Both the Tupolev Bear and the Ilyushin May are driven by four large turboprop engines, but the Bear has huge contra-rotating props on each one. The extra set of blades showed up clearly on the display.

  “See these four groups of doublets,” Tom said as he pointed to the close lines on the display. “That signal is the sound of his propellers. Each set of contra-rotating blades generates two frequencies that are really close to each other. Only a Tu-142 Bear Foxtrot has that kind of signature. And if we can hear the sound of his props, then he’s close. What should we do?”

  Both planes were armed with ASW torpedoes, although there was no risk of attack this far away from Russian territorial waters. A greater danger was posed by the planes’ suite of ASW sensors. They carried radar, an ESM sensor that could detect other radars, and a short-range magnetic sensor called MAD that could sense the thousands of tons of steel in Memphis’ hull. They also carried dozens of sonobuoys that could be dropped in patterns designed to detect a sub—if the plane’s crew thought there was cause to use them.

  Had this plane detected them? Were they responding to a report of a Yankee nuke approaching their waters? Or were they on their way home after a training mission? If Memphis was detected, or if the Russians even suspected there was a U.S. sub in the area, they would flood the area with ships and aircraft.

  “Set up a track, and rig for ultra-quiet,” Jerry recommended.

  “Should we change depth?” Holtzmann asked.

  Jerry thought for a beat, then said honestly, “I don’t know.” Working it though, he reasoned, “If we go deep, we could get a little farther away from his MAD sensor, but if he drops sonobuoys, he’ll put them on both sides of the layer, and we won’t be able to hear him as clearly on the far side of the layer.”

  The “layer,” or thermocline, was a sudden change in the temperature of the seawater that partially reflected sound waves. The depth of the layer varied from day to day, but sub sailors always made it their business to know where it was, and to use it to their advantage. Putting the layer between a sonar and the sub was like hiding in the shadows. It didn’t make you invisible, but it did make you harder to spot.
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br />   He paused, then said, “I recommend staying at this depth.”

  Holtzmann nodded, “Do it.”

  Jerry stepped back to the center of the control room. “Helm, all ahead one-third, make turns for five knots. Rig ship for ultra-quiet.” He turned to Holtzmann. “Should we notify the Captain?” As he asked his question, he heard his order echoed over the IMC: “Rig ship for ultra-quiet.”

  “We’d be in big trouble if we didn’t,” replied the ensign. He picked up the phone and dialed a number. “Captain, Officer of the Deck. Sir, sonar’s detected a Bear Foxtrot off our port side, drawing rapidly to the right, evaluated as close. We’ve reducing speed and rigging for ultra-quiet.” He paused for a moment, then answered, “Yessir.”

  Hardy stepped into the control room moments later. He stopped at the chart table for a moment, then studied the Bear’s track on the fire-control system. Silently, he headed toward the sonar displays as the watch team scrambled out of the way.

  The waterfall display now showed about five minutes of track history, a single fuzzy line angling to the right, straight and steady. The Russian was continuing on his way

  The Captain returned to the plot table, then the sonar display. He started to speak but caught himself before saying anything. Finally the petty officer manning the fire-control position said, “Contact is past closest point of approach and opening.”

  He spoke softly—not a whisper, but not a normal speaking voice either. Jerry noticed that the control room suddenly seemed quieter. He realized that many of the familiar machinery noises were missing from the background. He also felt the boat slowing, a subtle difference in the deck’s vibration.

  Hardy also spoke softly. He ordered, “Maintain this speed for thirty minutes after contact is lost, then resume normal speed and secure from ultra-quiet.”

  “Aye, aye, sir,” Holtzmann acknowledged.

  Hardy left, but a minute later the two ladies entered, almost breathless. “What’s ‘ultra-quiet’ mean?” demanded Patterson. “What’s happening?” asked Davis. Concern filled both their faces. Their voices, also full of concern, were raised and sounded harsh in the quiet control room. A soft chorus of “Quiet, please” and “Speak softly” surrounded them. Even Patterson looked embarrassed as the two were hushed.

  “It’s just a precaution,” assured Holtzmann. “Sonar picked up a Russian patrol plane and we went quiet to make sure it didn’t pick us up.”

  “You mean it almost found us?” Concern grew to alarm on Patterson’s face. She started to speak softly, then forgot as emotion filled her voice.

  “No, ma’am, there’s no sign of that. It passed close enough for us to hear it, but there’s no indication it changed course or did anything but continue flying from point A to point B. It’s headed away from us now, but just to be on the safe side, we’ll lay here in the weeds for a while, just in case he did drop a sonobuoy or three.”

  “And they can hear us if we speak too loudly?” Emily’s question was a mixture of curiosity and surprise.

  “Ma’am, at ultra-quiet, we reduce speed to a creep. This not only reduces the flow noise as the boat’s hull passes through the water, it also lets the engineers shut down some of the machinery. Unnecessary equipment, like some of the ventilation fans, are turned off, and some normal activities, like cooking in the galley, also stop. And all off-watch personnel are supposed to get into their racks and stay there.”

  “Like us?” Emily asked.

  Holtzmann nodded. “Like you two ladies.”

  “And they can really hear us walking around and talking?” Patterson asked.

  “It isn’t that the walking and talking are all that noisy.” Holtzmann explained. “It’s that everything else is that quiet. The whir of a fan, the sound of pans clattering in the galley, or a loud conversation may be the first thing they pick up.”

  The XO had come in during Holtzmann’s explanation. He checked the fire-control track and the chart, then turned toward the ladies. “This is the part where we lie on our bellies in the mud while searchlights pass overhead. This is where we paint our faces green and merge with the underbrush. If they find us on the way in, it’s going to be harder—a lot harder—for us to get the job done.

  “It’s not like it was back in the ‘70s and ‘80s, when we had a huge acoustic advantage,” he continued, “and we are heading straight for the Russian Navy’s front yard. Not only is their Northern Fleet headquarters here, but half a dozen sub and surface ship bases and as many air bases. In other words, the entire Northern Feet’s right over there.” He pointed to the southeast.

  “Imagine how we’d feel if a Russian submarine went snooping into the Chesapeake Bay. How would our Navy react?”

  “It’s going to be hard to type lying down,” Patterson declared resignedly, then left, with Davis following her. As she left, Bair said, “It shouldn’t be too long—this time.”

  The signal from the Bear faded completely a few minutes later without changing course. They waited thirty minutes, the tension gone but prudence still in charge, then secured from ultra-quiet. They resumed normal transit speed, but Jerry sensed a different mood in control: not grimmer, but quieter and more focused. From here on they could expect to encounter Russian units at any time.

  * * * *

  It was almost the end of his watch before anything else happened to break the quiet. Jerry looked up from his quals book as sonar announced, “Conn, sonar, new contact bearing one six zero degrees. Designated new contact sierra seven seven. Contact is a distant active warship pinging with a medium-frequency search sonar. Probably a patrol craft.”

  Holtzmann told Jerry, “You make the report to the Captain this time. I’ll get us quiet.” As he gave the orders to reduce speed and rig the boat for ultra-quiet, Jerry picked up the phone, dialed the Captain, then repeated sonar’s report.

  Hardy replied, “Thank you, Mr. Mitchell. What are your recommendations?”

  Jerry replied, “Continue on base course, sir.”

  “Because a medium-frequency sonar has a relatively short range?” Hardy prompted.

  “Yes, sir.”

  “Wrong answer, mister!” Hardy’s voice was harsh. “Order a turn to the north right now, new course zero two zero. I’ll be there in a minute. See if you can figure out by then what your mistake was.”

  Puzzled, Jerry put down the phone and told the OOD about the course change. Holtzmann let him issue the order and then asked about Jerry’s expression. “I recommended that we stay on course, but the Captain said that was wrong. I don’t understand why. Russian patrol craft all have short-range sonar, and he’s not even close to us.”

  “All true,” Holtzmann replied. “But what time of year is it?” he asked.

  “Summer,” Jerry answered, confused by the question.

  “In the Barents,” Holtzmann continued. “It’s a short summer up here. The weather’s decent, and the Russians cram a lot of exercises into these few months. Now, we know there’s a patrol craft out there pinging, but he’s too far away to be pinging for us. So what’s he pinging for?”

  “A Russian sub.” Jerry answered, beginning to understand.

  “Exactly,” Holtzmann confirmed. “There’s a decent chance that a patrol ship is getting practice on a live sub or that a sub’s getting practice with a live pursuer, probably both. Now the patrol craft can’t pick us up this far away, but if there’s sub around, then we are in an entirely different ball game.”

  Hardy arrived as Holtzmann finished his explanation. “Anything more from sonar, Mr. Holtzmann?” Hardy asked.

  “Sonar reports a single pinger only. They evaluate it as a Bull Horn sonar, bearing correlates with a passive sonar contact, possibly a Grisha. But it’s not a single contact. They’re getting several similar passive contacts, all close together, all with a very slow right bearing drift.”

  “A group of ASW patrol craft,” Hardy concluded, “with one conducting an active search.” He stepped over to the intercom and pressed the swi
tch. “Sonar, conn. Sort out those passive contacts and make damn sure they are all surface ships. And keep a sharp eye to the south for anything that might not be a surface vessel.”

  “Conn, sonar aye” came over the speaker from sonar.

  Hardy turned back to face them, but his explanation was for Jerry. “Individually, a Grisha or a Parchim isn’t much of a problem. A couple of short-range sonars, ASW rocket launchers, and ASW torpedoes. We can outrun one or sink it with one torpedo. But they hunt subs in packs, usually in groups of three or four. They spread out in line abreast and march back and forth across a swath two dozen miles wide. They also like to work with ASW aircraft and helicopters. Right now, they’re practicing how to hunt us. We’re going to do our best to avoid giving them a real target to train on.”