The calls from Iceland came at night back then, telling Lt. Cmdr. Ron Gracy to be here in the morning.
Gracy needed to find the next Soviet submarine, cruising through the Atlantic Ocean. The ships were always heading toward a spot east of Bermuda and parallel with North Carolina. They would wait there, two at a time, loaded with nuclear missiles.
Gracy's job? Report to a Naval team in Iceland that was trying to keep tabs on the boats. The team received information from hydrophones, a type of underwater mic they installed on the ocean floor. From as far as 1,000 miles away, sound waves streamed from submarines. The waves changed the pressure in the water, and the hydrophones captured those changes, sending along a measurement through underwater cables.
The team in Iceland looked at the long line of hydrophones, seeing where the sound wave was strongest. This gave them an estimate the direction from which the boat was coming. They also looked at the frequency of the sound wave, revealing the specific boat.
Name: Ron Gracy
Home: Ringgold, Ga.
Military branch and rank: U.S. Navy, commander
Still, the group didn't know exactly how far away the submarines were or from which direction, precisely, they came. That's where Gracy, a co-pilot, and the seven other members of his crew came in.
"It was a big cat-and-mouse game," Gracy said. "Keep ahead. Keep ahead. For every intelligence, there's a counterintelligence. And then there's a counter-counterintelligence."
After a night's sleep and a good meal, they jumped in a Lockheed P-3 Orion, a four-engine aircraft built for flights lasting as long as 12 hours. At about 250 mph, the team flew to the general area where the submarine might be. They moved around at about 20,000 feet and dropped a couple sonobuoys.
The buoys had a hydrophone on a cord that unravelled into the ocean, and antennae on top. The team on the plane listened to a receiver, each channel tied to a different hydrophone. The one that came back with the loudest noise was the closest to the submarine.
Then, Gracy or his co-pilot would slow down to about 200 mph and descend to about 1,000 feet above the water. They would drop six to eight more sonobuoys, the collection forming a circle about 4,000 yards in diameter. All the sound would stream into the receiver in the plane, giving the team an even more precise estimate of the submarine's location.
Job accomplished, Gracy and the rest of the team headed to Alexandria, Va., and gave a Naval officer the data.
Gracy did this over and over from 1969 to 1972. The Navy used the information to become smarter. It would improve the technology on its monitoring equipment, becoming even more precise as it tracked the Russian submarines. It would also try to figure out ways to make its own boats quieter, harder to track. In the middle of the Cold War, Gracy knew a team of Russian servicemen were trying to pull the same tricks he was.
Gracy earned degrees in mechanical engineering and communications engineering. In his 23-year career, he taught calculus, differential equations and vector analysis at the Naval Academy and retired as a commander. He worked for NATO for three years, helping member countries install reliable communications stations and encrypted phones for heads of state.
But he is most proud of his working tracking submarines.
"That became my challenge," he said. "To be able to find and destroy submarines."
Contact staff writer Tyler Jett at 423-757-6476 or firstname.lastname@example.org. Follow him on Twitter @LetsJett.