A Time of Danger : Blind Spot Is a Menace for Surfacing Submarines

Carefully, deliberately and by the book, the crewmen maneuvered the U.S. Navy submarine up from the depths of the Mediterranean Sea. They listened to the sonar for telltale noises. Nothing. The order was given to climb.

As the periscope poked above the surface, the looming image of a 100,000-ton tanker came into focus, dead ahead.

“He was so big that even head-on, bow-on . . . we couldn’t hear his screws (propellers) through his hull, so we didn’t know he was there,” recalled retired Vice Admiral Patrick J. Hannifin. “We came up and went down in a hurry.”

Hannifin’s submarine escaped harm’s way during the near-collision, which occurred more than a decade ago in the Mediterranean Sea. Two weeks ago, off the coast of Los Angeles, the crew of the submarine Houston was not so fortunate. The crew of the tugboat Barcona was less fortunate still.

The nuclear-powered Houston, on standby for filming of the motion picture “The Hunt for Red October,” a fictional saga of a Soviet submarine skipper’s defection to the United States, snagged the Barcona’s steel tow cable and yanked the tugboat backward and under in less than a minute. One crew member drowned and two others survived.

A Navy spokeswoman at the Houston’s home port in San Diego called the incident “freakish,” but the submarine only two days later, operating in roughly the same waters, sliced through a trawler’s fishing net. The Navy says both incidents are under investigation.

Navy officials have left many questions unanswered in the two recent accidents off the Southern California coast involving the Houston, a fast-attack submarine. But evidence has emerged that at least one of the incidents occurred while the Houston was in a blind spot similar to the one described by submarine experts interviewed last week.

Strange as it may seem to civilians, submarine experts say that highly sophisticated Navy submarines sometimes travel through the oceans of the world nearly blind to what is around them. In fact, during some maneuvers the submarine captain operates with a blind spot not unlike a driver changing lanes on a freeway.

Under Navy policy, submarines rarely use the sensitive “active” sonar systems on board because in order to do so they must emit signals that could reveal their location. Instead, they rely on “passive sonar,” which means carefully listening for the sound of engines, clanking chains or any other auditory clues.

No Noise, No Detection

But if a vessel is not making any noise, there is little chance that the submariners will detect it.

“It’s quite extraordinary,” said Angus Peetz, a research aide to George Foulkes, a member of the British Parliament who has pressed for a full-scale investigation of similar sub incidents off the British Isles. “They can hit targets 2,000 miles away, but they can’t spot a fishing boat above them.”

While the issue of sub collisions is something relatively new to California mariners, it has been a growing controversy in Britain and Ireland. Members of both the British and Irish parliaments are demanding to know what role submarines may have played in the “mysterious” disappearances, sinkings and snaggings of several dozen fishing boats in the Irish Sea, resulting in the loss of more than 100 lives since 1980.

Officials with the U.S. and British navies have said that their submarines have not been involved in fatal incidents in the area. However, officials in both navies have confirmed details of collisions and several snaggings involving submarines and civilian vessels.

The collisions, naval experts say, illustrate a point that remains true today: Surfacing from the deep is a maneuver that challenges even the most experienced skippers with the highest-tech gadgets on board.

Most Vulnerable Time

“It’s that time when the submarine is most vulnerable,” said Hannifin, who was commander of all U.S. and NATO submarines in the Mediterranean from 1971 to 1973, then went on to become the director of the Joint Chiefs of Staff. “He’s really blind. The problem is that a submarine completely submerged can’t see anything.

“It can hear, but it can’t see. It can hear a fishing boat, for example, if the fishing boat is running its engines. What it can’t hear are fishing nets or barges being towed, because barges don’t make any noise.”

In order to minimize the chances of running into another vessel, submarines generally travel well below the surface. When it is time to ascend, they move swiftly to periscope depth.

“There is a period, truly, of uncertainty as you go through this transition from the deep submerged state to a shallow submerged state, and so you very carefully search around,” said Capt. Thomas C. Maloney, retired commanding officer of a nuclear-powered submarine of the same class as the Houston.

“You maneuver the ship to see if there’s some target behind you,” Maloney said, “and then you very quickly try to bring the ship up so you can look out through the periscope.”

Maloney described the transition period as a tension-filled time and compared it to an automobile on a freeway. “Once in a while, you get ready to change lanes and all of a sudden you find there’s somebody in your blind spot,” Maloney said, “even though you thought you’ve done a pretty careful search.”

Masked Sounds

Such events occur rarely, Maloney said, and explanations vary. Sometimes another loud ship in the distance masks the sound of the closer ship, he said. Or sometimes it’s simply a sailboat that was making no detectable noise.

Still, active sonar, which is capable of detecting silent objects, is rarely used. Using passive sonar, a submarine crew member simply listens for noises, but with active sonar, the operator can send out sound waves that will bounce back to the submarine with a “ping” if it strikes an object.

The active system works best in detecting totally submerged objects, Maloney said, but is less reliable when aimed at the surface. Depth, water conditions, surface waves and other variables all can generate sonar “clutter” that cuts down on reliability, he said.

The overriding reason that active sonar is rarely used, however, is security.

“When you use active sonar, you give your position away,” said James Bush, a retired Navy captain and former submarine commander who now works with the Washington-based Center for Defense Information.

Active sonar is generally reserved for “battle situations,” Bush said. “You’re going to shoot a torpedo at him anyway, so why not make sure you know exactly where he is.”

In any case, Bush and others said, it is highly unlikely that any sonar system would detect a fishing net. Navy officials confirm that fishermen from around the world have been reimbursed for nets and catches lost when submarines accidentally sliced through them, but precise figures were not made available last week.

Bernard Moffat, general secretary of the Celtic League, an organization that fosters cooperation among the Celtic areas of the British Isles, has been monitoring military activity in the narrow, relatively shallow and heavily fished strip of sea between Ireland and mainland Britain known to submarine crew members as “Rat’s Run.”

100 Civilian Deaths

Since 1980, he said, there have been 21 disappearances of civilian vessels and more than 100 civilian deaths. The incidents have occurred in calm-to-moderate sea conditions, and Moffat claims that at least some of them probably are linked to submarines.

In 1982, the British Navy paid damages after the submarine HMS Porpoise sank a fishing boat. All crew members were rescued.

But U.S. submarine involvement in other accidents is less certain. Moffat acknowledges that “we can’t say they’re definitely linked to submarines,” but he insists that “in almost all cases, the incidents occurred in what are listed on admiralty charts as designated submarine exercise areas.”

U.S. Navy officials confirm only a handful of close encounters in the Irish Sea.

In April, a British trawler named Laurel was apparently snagged by an American sub off the Isle of Man. The U.S. Navy released a report saying only that the crew had no indication of the snagging, but minor paint scrapes found on the sub “were assumed to be the result of the snagging.” An investigation is continuing, the Navy said.

Three months earlier, U.S. officials say, a surface collision occurred between a U.S. submarine and the fishing vessel New Dawn. Authorities are awaiting a resolution with the insurance company representing the boat owner.

Net-snagging incidents in 1987 prompted the U.S. Navy to pay out more than 28,000 British pounds in damages to the owners of the British fishing vessels Heroine and Summer Morn.