“We could be following a decoy,” Bush said.
Tolbert was quiet. If they were following a decoy, it was no bigger than a torpedo. There was an easy way to determine whether they were following a small decoy or a large submarine — go active and measure the size of the object. But that would give away North Dakota’s presence. However, if they were following a decoy, they needed to figure it out fast before Dolgoruky slipped away.
“Transmit on MFA,” Tolbert ordered, “Forward sector only, five-thousand-yard range scale.”
A moment later, North Dakota transmitted on their Mid-Frequency Active sonar and the return lit up the sonar screen; directly ahead was a small white blip. Chief Bush reported, “Contact width is less than five feet.”
Tolbert gritted his teeth. He’d been fooled into following a decoy. The Russian captain was good. But the game wasn’t over. They hadn’t been following the decoy very long and could still regain track on Dolgoruky. Tolbert recalled the short burst of cavitation they’d detected. That must have been when the decoy was launched. An examination of the navigation plot determined that spot was ten thousand yards to the north.
“Pilot, come to course north,” Tolbert ordered. “Sonar, Conn. Prepare to transmit MFA, forward sector, ten-thousand-yard range scale.”
North Dakota swung back to the north, and as she steadied up, Bush reported, “Conn, Sonar. Ready to transmit MFA.”
“Transmit.”
North Dakota transmitted, but this time, instead of a single contact, there was a wide band of white running across the screen.
“Ice keel at ten thousand yards,” the Sonar Supervisor announced. “No contacts between us and the ice keel.”
Tolbert immediately discerned what the Russian captain had done. He had gone shallow to place the ice keel between the two submarines, and was slipping away as North Dakota followed his decoy south.
There was no time to lose. Tolbert ordered, “Pilot, ahead full,” then turned to the Officer of the Deck. “Station the Fire Control Tracking Party.”
A few minutes later, the Fire Control Tracking Party was stationed, returning the Control Room to full manning as North Dakota sped north.
Captain Stepanov checked the clock in the Command Post. Dolgoruky had hidden behind the ice keel for thirty minutes. At ten knots, the American submarine would have traveled far enough for Dolgoruky to slip away.
“Set Hovering to one hundred and forty meters,” Stepanov ordered. They were pointed directly at the ice keel, and would need to drop beneath it before restoring propulsion.
The Compensation Officer dialed in the depth, and valves in the variable ballast tanks opened, flooding water into the tanks. Dolgoruky began its descent.
Stepanov added, “Resume transmitting on top- and bottomsounders.”
The two sonars started transmitting again, measuring the distance to the ice and bottom. As Dolgoruky dropped beneath the ice keel, offering a clear view of the water to the south, a report blared from the speakers. “Command Post, Hydroacoustic. Regain of Hydroacoustic seven, bearing one-seven-eight. SNR has increased nine decibels!”
Stepanov didn’t need to do the calculations to know they were in trouble. They had previously held the American submarine at four thousand meters, which meant it was now only five hundred meters away.
Hydroacoustic followed up with, “Detecting broadband propulsion noises from Hydroacoustic seven. Contact is operating at high speed!”
Stepanov was no longer worried about detection. The American crew had discovered they were following a decoy much quicker than he expected, and their captain had run back up the decoy’s track, directly toward Dolgoruky. Assuming the American submarine was traveling at twenty knots, it would close the remaining distance in forty-five seconds.
Dolgoruky was at all stop. They could not turn out of the way. That left only two options — up, or down. An Emergency Blow would send Dolgoruky surging toward the ice, crushing the conning tower and maybe even puncturing the pressure hull. However, Dolgoruky was already descending, and maybe they could drop below the American submarine in time.
Stepanov shouted out, “Disengage Hovering! Flood all ballast tanks!”
Commander Tolbert leaned over the navigation plot, examining the white dot representing North Dakota. They were on course three-five-eight, approaching the point where the Russian captain had launched the decoy, but they had not yet regained Yury Dolgoruky on any sensor. However, they were traveling at ahead full, blunting the range of their acoustic sensors, and Tolbert decided to slow and take a look around.
“Pilot, ahead two-thirds.”
The Pilot entered the new propulsion order and as North Dakota slowed, the Sonar Supervisor announced, “Conn, Sonar. Hold a new broadband contact on the spherical array, designated Sierra three-seven, bearing three-five-eight. Analyzing.”
Tolbert acknowledged the unusual report. Initial broadband gains were almost always merchant ships, and there were no merchants under the ice.
Chief Bush followed up, “Conn, Sonar. Hold the contact at zero elevation. SNR has increased threefold since we gained contact and continues to rise.”
The Sonar Supervisor’s report made no sense. How could Signal-to-Noise Ratio triple in only twenty seconds? He glanced at the MFA display on one of the sonar consoles, noting the white-banded return from their active pulse, painting the image of an underwater ice ridge. A ridge they were passing under now.
It was at that moment that Tolbert understood. The broadband contact they had picked up was Dolgoruky, dropping below the ice keel she had been hiding behind. They had picked her up on broadband, which meant she was close, and if signal strength had tripled in twenty seconds, that meant—
North Dakota jolted upward, knocking Tolbert off balance. He grabbed on to the navigation plot as a metallic screech tore through the air. Seconds later, everyone in Control was thrown forward as North Dakota slowed suddenly and the bow tilted downward.
10
The second jolt was more violent than the first, knocking every watchstander not buckled into their chairs to the deck and launching every unsecured item toward the forward bulkhead. The loose items crashed to the deck as the metallic screeching ceased, and North Dakota’s bow swung up to an even keel. The silence lasted for only a few seconds. The Flooding Alarm sounded, followed by a report blaring from the emergency 4-MC system.
“Flooding in the Engine Room! Flooding in Shaft Alley!”
The Co-Pilot reached toward the Ship Control Station and turned toward Commander Tolbert, awaiting direction to Emergency Blow. As Tolbert caught the Co-Pilot’s eyes, he realized an Emergency Blow would send them careening toward the surface in an uncontrollable ascent, smashing into the ice cap.
“Do not Emergency Blow!” Tolbert shouted.