By Dylan Phillips-Levine and Trevor Phillips-Levine
Somewhere in the Western Pacific.
USS John Basilone, DDG-122
“Green deck, clear to launch,” came the call from the MH-60R Landing Safety Officer aboard the destroyer.
“Saber 412 clear to launch,” replied Splash.
“Steady hover, 125% torque,” he read off his instrument panel.
He lifted the collective to maintain a steady hover. The torque indications fluctuated between 118% and 125%. The tailwind and hot weather forced the engines to work harder than usual to lift the MH-60R “Seahawk” helicopter off the deck. He could feel the engines straining to lift the helicopter loaded with fuel, torpedoes, and a new anti-submarine warfare suite – even if it was one crewmember light.
Splash moved the cyclic aft and pulled up the collective until the chin bubble of the helicopter was just over the deck’s edge. Colloquially known as the perch, this position provides safety in case of an engine failure. If an engine failure occurred, he could save the aircraft and crew if he acted quickly enough by lowering the collective and dropping the noise.
“Clear left, turning left, clear to depart.” He moved his feet against the anti-torque pedals and canted the nose 45 degrees to the left to leave the destroyer.
“We’ve talked about this before. You need to make sure you have headwinds when you takeoff, especially when hot and heavy.”
Sigh. Not again. “I didn’t want to change the course of the ship. We’re flying safely, aren’t we?” Splash challenged.
“We’re flying. Safely is up for debate,” came the response from Petrel.
Splash didn’t respond to the snark. He had learned better, and besides, he was still stinging from when he lost the dipping sonar, “the dome,” last year hunting subs in the North Sea. The eval board had cleared him of wrongdoing, but the mishap would stay in his NATOPS jacket for the rest of his career. But now was not the time to reflect on his past.
“Saber, comms check,” said the Anti-Submarine Tactical Air Controller (ASTAC) aboard the Basilone.
“Lima Charlie, standing by for tasking” replied Splash.
“Saber, ASTAC. We have a tail contact bearing 320, unknown range – request you investigate.”
“Saber, en route,” replied Splash, turning the helicopter on a course to intercept the contact.
A tail contact could only mean one thing: there was a submarine in the area. Splash lifted the nose and climbed to an altitude to gain radar coverage. His radar picture was covered in hundreds of contacts – floating debris from crashed NGO ocean drones, surfaced whales, and even the white caps from the rough seas populated his screen. The sensor operator, Chief, started slewing the thermal camera or FLIR, to each one of the contacts, attempting to find the submarine if surfaced. But with hundreds of contacts he was unlikely to find the target this way.
“Chief, slew the FLIR to the contact 320 and 35 miles out,” came another unsolicited call over the crew communication system from Petrel.
Chief complied, slewing the FLIR to the correct elevation and azimuth. He cycled through various sensor modes until eventually the grey blob came into focus and then remained on screen. Something was there.
“How the hell did you see that? All the contacts look the same,” the sensor operator muttered, as he spat into a dip bottle.
“Experience,” came a sarcastic reply from Petrel.
This was not Chief’s first time hunting submarines. He had finished training Fleet Replacement Squadron first in his class eight years earlier and was meritoriously promoted. He was the sensor operator that found the Chinese wolfpack in Malacca and was credited with saving the Truman a few years back. He scrunched his face, trying to come up with a witty retort, but was interrupted by another radio call.
“ASTAC, Saber, contact 320, 35 miles from my position. Pushing you the contact data now,” came the call from the helicopter tactical controller on Basilone.
“I’ll generate the next fly-to-point. Chief, start the Sonobuoy automatic checklist and maintain FLIR contact. Splash, proceed to the fly-to-point on the search pattern,” ordered Petrel.
Chief took a deep breath. They had to work together as a team. In school they told him that trust would be the hardest thing. The next hardest thing for Chief was playing nice with others.
“Roger,” Splash and Chief answered in unison. It was clear who was in charge.
Chief moved the hand control unit to maintain contact. Approaching the first fly-to-point, the FLIR slewed off and the radar picture froze. Chief frantically tried to reacquire the contact but without success. The FLIR and radar had overheated. Although the aircraft was designed to operate in austere environments, back-to-back deployments and extended periods at sea had wreaked havoc on maintenance and avionics.
“You’ve got to be kidding me. Radar and FLIR are down. We’re hunting blind. I’m going to try and reset the multi-mode radar and FLIR.”
“Negative, Chief. Continue with ASW prosecution. If the submarine didn’t know we were here before, they definitely do now.” Petrel was running the hunt now.
Chief swore, but he knew it was right. Even without the distinct acoustic signature of an approaching helicopter as a warning, the Chinese supposedly had a database of electromagnetic emissions of U.S. ships and aircraft. Any halfway decent captain or even his political commissar would have given the order to submerge by now. Restarting the FLIR and the radar would give the submarine time to get farther away from its last known position. They had to get acoustic sensors in the water – fast. If the submarine was traveling at a leisurely 10 knots and the reset cycle took five minutes, the submarine would almost be a mile away by the time they got the sensors back up. Radar and visual sensors would certainly help in the high-speed world of dogfighting where vision is everything. But in the underwater version of Marco-Polo, sound is everything and every second without a contact increases the odds of the submarine escaping. Time was of the essence.
Chief complied. The FLIR and multi-mode Radar would have to wait. “Automatic sonobuoy launching checklist,” replied Chief.
Splash replied: “Ready light illuminated, capturing fly-to-point for automatic launch.”
“Chief, analyze the water column before we launch active and passive sensors.” Another unsolicited call from Petrel.
In the frenzy of losing sensors and contact, both Chief and Splash had forgotten to analyze the water column, a critical mistake. If Marco-Polo is the game, the rules are written in the water column data. Underwater distortions, bottom bounce, and complex sound velocity-profiles distort the accuracy and complicate the game.
“Nice catch – I was just testing you,” replied Chief, trying to recover.
“I don’t mind doing your job, it’s why I’m here.” The response came back dripping with sarcasm.
“Why does it have to do that?” Chief muttered. “They didn’t have to make it that way.”
His brooding was interrupted by the callout from Splash.
“Fly-to-point capture in 3, 2, 1… buoy away.”
Chief immediately brought up the acoustic display, turning up the hydrophone volume and looking through the acoustic noise for any signs of a submarine. Even though the volume was turned all the way up, the only thing he could hear was the constant thump-thump-thump of the helicopter blades pierced by the high pitch whine of his tinnitus, earned over thousands of hours of flying.
“Proceed to the next fly-to-point, I’ll continue to monitor the first buoy for signs of contact,” Chief directed Splash.
“Copy. Proceeding to the next fly-to-point. Buoy away now, now, now.” Both of them could hear the distinct fwoosh sound as the compressed air shot out the sonobuoy.
Chief monitored the buoys. The aural tones were overwhelming his senses. He turned off the volume so he could focus on the visual display of the acoustics. The green static had transitioned to a sea of colors. The screen was flooded with frequencies emanating from all directions. He had to isolate the sub’s distinct frequency.
Petrel chimed in. “Contact, 320, unknown range. Fly to the next fly-to-point for buoy drop and triangulation.”
Chief breathed a sigh of a relief. He welcomed the help although he could do without the know-it-all attitude.
“Fly-to-point capture in 3, 2, 1… buoy away,” said Splash again.
Chief quickly tuned up the sonobuoy to triangulate the contact. Thanks to Petrel’s earlier information, Chief was able to quickly identify the bearing and distance to the contact.
“We have a bearing line, let’s dip and get a solid active return before we go lost contact again,” Splash said.
Another challenge came across the crew communication system. “Do not dip due to weather and sea state. We already have contact. We won’t be high enough to maintain contact with the sonobuoys if we dip,” said Petrel.
“We have weak contact,” Splash protested. “We’re going to dip to get solid contact and establish a firing solution.” It was clear splash was in control.
“Automatic approach checklist complete, standby to dip,” said Splash.
“Hover mode, hover checks complete, 650 degrees C #1 engine, 700 degrees C #2 engine,” replied Petrel.
“Steady hover, down dome,” replied Splash.
“Dome stopped. Pinging. Negative contact, sir,” replied Chief.
“Keep trying different depths. She’s here and we’re going to find her,” said Splash.
“Changing depth. Pinging. Negative contact, sir, ” Chief replied.
“Dip below the second gradient of the water column,” Petrel ordered.
“Contact! 320 at 2000 yards.” Splash could hear the excitement of the hunt in Chief’s voice. The team was finally working together.
Just when the crew had found their synergy and the contact, Petrel announced over the crew communication system, “#1 engine 690 degrees C and rising, 700 degrees C and steady #2 engine, depart the dip.”
Splash thought the warning was overly cautious. Petrel always followed the book. Always. “Negative, we’re staying in the dip to set up a firing solution. The #1 engine is still performing better than the #2 engine,” Splash replied. “Chief, start the torpedo launch checklist.”
“Going through the manual presets now. We’ll be ready to launch in just a second,” replied Chief.
Bang! Pop! A series of loud bangs was followed by the immediate fluctuations in torque and turbine gas temperature. Then came the unmistakable and chilling whine of an engine spool down.
“Engine 1 roll back, Control Nr, contingency power switch on, single engine conditions establish,” a voice ordered Splash.
Splash didn’t even have time to interpret the instruments. He didn’t have time to think, just to act. He followed the instructions without hesitation. He lowered the noise and collective and immediately exceeded cable angle limits. It was a miracle that the dome didn’t sheer off. Salt had encrusted the already strained engines and caused a compressor stall on the #1 engine.
“Up dome,” said Splash.
“Can we find it my way now?” Petrel asked, with a touch more condescension.
“Sorry,” replied Splash, his tone betraying his bruised ego.
“I warned you that the temperature was rising and to depart the hover,” Petrel stated matter-of-factly.
“We had contact with the target, I didn’t want to lose it,” contested Splash.
The voice over the radio continued questioning Splash’s decision making. “What good is contact if we crash?”
“I can still help,” Splash said in an attempt to redeem himself. He looked left to the seat beside him and then back to his instruments, briefly forgetting he was the only pilot.
“If you want to help, listen to me – fly the search pattern I made to regain contact,” Petrel continued.
Splash looked down at the tactical display. A new fly-to-point was flashing on his display for approval. He pressed acknowledge on the screen and started flying to it.
“Returning all the buoys, if she’s out there, I’ll find her,” Chief said confidently. His track record for the day proved otherwise, thus far.
Chief tuned up all the previous buoys. Once again, his displays were covered in a sea of colors caused by different sounds. His specialty was analyzing data to find submarines, but even with 2,000 hours under his belt, he couldn’t always make sense of the data.
As if sensing his loss of situational awareness, Petrel replied, “Chief, I’ll compare the raw data to the historical database of current submarines in order to find it.”
Chief had been called many things, but never inept, and never so eloquently.
Petrel compared the raw data with the historical database at the speed of light. “Contact 320 at 2000 yards. Developing a torpedo firing solution,” said Petrel.
“I still don’t see what contact it’s looking at. There’s no range or bearing,” replied Chief.
Petrel, however, had combed through the data and was able to produce several bearing lines on the display that all met at a common intercept point. It found the submarine and developed a firing solution in seconds.
“Master Arm,” Petrel commanded.
“Armed,” replied Splash. At least Petrel needed him for that to satisfy the “Human in the Loop” requirements.
“Torpedo presets set, standby for torpedo drop,” replied Petrel.
“Torpedo away now, now, now,” Splash said as he captured the torpedo fly-to-point. He dropped the Mk 60 lightweight-torpedo on the computer calculated impact point.
The Mk 60 was wire guided by an onboard computer. By combining the data from the buoys in real time, the computer guided the torpedo to the area of interest. Impacting the target, however, was at the mercy of the torpedo’s legacy sonar.
Petrel combed through the sonobuoy data intently, waiting for the signs of an explosion. After 30 seconds, Petrel came back to life in the helicopter with “Impact,” confirming a positive hit.
“Direct hit, RTB,” Chief responded after hearing the torpedo impact the training drone. It wasn’t as dramatic as the sound of a submarine breaking up and sinking down to crush depth, but it was still loud enough to make him flinch.
It was only an exercise, but it validated what the DARPA engineers had been saying for months. Petrel, their sub-hunting AI, could replace the co-pilot and better manage the rest of the crew than the pilot could. Dropping pilot retention rates and budget cuts in the 2020s left the Navy critically short of pilots. They stripped the rotary-wing community of everyone they could spare to man the legacy fighters. Petrel was originally intended to just be an AI co-pilot, allowing the Navy to field more ASW squadrons even with the chronic pilot shortage. But Petrel proved to be more than just a digital co-pilot of the “minimally manned crewing model,” as the Navy called it. Petrel made the crews more lethal. Together, they could act faster and sort through decades of historical acoustic data mid-fight.
After years of reinforcement training, Petrel was the ultimate mission commander. The crew just had to trust it. But that trust didn’t come easily.
Dylan Phillips-Levine is a lieutenant commander in the U.S. Navy. He serves as an instructor in the T-34C-1 Turbo-Mentor as an exchange instructor pilot with the Argentine Navy. He previously served as an instructor pilot in the T-6B Texan II with VT-6 and has flown the
MH-60R Seahawk with HSM-46. He can be reached on Twitter @JooseBoludo.
Trevor Phillips-Levine is a lieutenant commander in the United States Navy. He is a naval aviator and serves as a department head in VFA-2. He can be reached on Twitter @TPLevine85.
Featured Image: “.dwnptrl.” by Andrey Vozny (via Artstation)
0 thoughts on “Petrel”
Well written! Great job!
Second the motion! Could not stop reading.