A sonar technician listening through his headset caught the trail of an “enemy” submarine just before a line of warships cruised through waters between Santa Catalina and San Clemente islands.
The whooshing sound of bubbles created by the submarine’s propeller had been picked up by passive acoustic monitoring, made famous in the movie “The Hunt for Red October.” The detection -- part of a sophisticated naval training exercise over the weekend -- popped up on green- and red-lighted screens in command centers aboard the aircraft carrier and its support ships.
If not for a recent federal court order, the accompanying destroyers would have begun to track the submarine by activating a powerful sonar that issues a loud ping and then waits for the echo to reveal the target’s location.
But at times this weekend, the sonar had to be turned off. A judge, concerned about the potential harm to whales and dolphins, forbade its use in the area between the islands, waters known for their rich abundance of marine mammals. The submarine soon got away in the murky depths.
And so began the war games that will continue this week, a final exam after months of training to determine if the carrier strike group lead by the Abraham Lincoln is prepared to meet threats of all kinds -- including submarine attacks -- before it heads to the Persian Gulf in March.
“This is a game of cat and mouse,” said Navy Secretary Donald C. Winter, who flew out from Washington to observe the training. “Any time we have to shut down our sonar creates huge problems for us. We want to do everything we can to protect the whales but not risk compromising our training.”
These training missions in Southern California waters have become a classic case of competing interests: environmental protection versus troop readiness. The training runs have been entangled in lawsuits, federal court orders and recently a move by President Bush to override the courts -- setting up a struggle between the executive and judicial branches of government.
The 6,500 sailors on six ships in the carrier group aren’t tuned in to the legal and constitutional challenges happening on shore. Each is focused on individual tasks in an elaborate choreography masterminded by Vice Admiral Samuel J. Locklear III, commander of the U.S. 3rd Fleet.
Locklear said he is working from a secret playbook that will test sailors’ mettle, distract them, spread the ships thin and probe for weaknesses. “They don’t know what’s coming,” he said.
Throughout the weekend, fighter jets catapulted off the aircraft carrier and then returned at night to make tail-hook landings on deck in stormy seas. Meanwhile, destroyers were maneuvering to sweep the horizon for hostile boats and scan beneath the waves for submarines.
As soon as the strike group moved south of the islands, the destroyers were allowed, under the terms of the court order, to turn on the midfrequency active sonar. The powerful sonar is used to hunt for the type of quiet diesel-electric submarines now operated by Iran, China, North Korea and three dozen other countries.
By midafternoon Saturday, the strike group located the submarine with the ship-based sonar. Helicopters were dispatched with a special dipping sonar that was lowered by cable into the water.
The ships tracked the enemy sub for a while, but it managed once again to elude them.
At 2 a.m. Sunday, the target submarine -- a U.S. sub playing the role of the enemy -- surfaced near the carrier and radioed to announce its location. In these games, it was a taunt that prompted a round of urgent, middle-of-the-night phone calls.
“It’s very embarrassing that the submarine got in on us,” said one Navy captain. “But it shows how a submarine can hide among pinnacles and seamounts, and we’ll have to learn from it.”
Tracking submarines, Navy officials say, is “an art steeped in science.” That is to say, it isn’t easy even with the powerful sonar.
One problem is that the ocean creates layers of water with different temperatures. Sonar can bounce off lower, colder layers, and clever submarine crews learn to mask their whereabouts by hovering beneath them.
Another challenge is that submarines can find hiding places in the nooks and crannies around islands and undersea mountains.
But these places also attract whales, dolphins and other marine mammals. So conservation groups and the California Coastal Commission have been pushing the Navy to be extra careful when using sonar in these areas to avoid harming marine mammals.
Although the Navy says there’s no evidence that these training missions have killed marine mammals in Southern California, other naval exercises using midfrequency sonar have been linked to whale and dolphin deaths in the Bahamas, the Canary Islands and elsewhere.
On Sunday, the crew aboard the destroyer Momsen showed Winter its multilayered strategy to protect whales. The efforts included reducing the power of midfrequency sonar by 75% any time a marine mammal was spotted within 1,000 yards. Sailors trained as lookouts scanned the horizon through powerful binoculars for whales and dolphins as sonar technicians listened for the mammals.
Winter said he was impressed with how the crew responded to an imagined whale sighting. Technicians quickly turned down the sonar power and then shut it off when the whale ventured within 200 yards.
U.S. District Judge Florence-Marie Cooper last year saw a similar Navy drill, although the destroyer remained in port in San Diego. After watching the demonstration, reviewing the scientific literature and the Navy’s own environment assessment, she called the Navy’s efforts “grossly inadequate to protect marine mammals from debilitating levels of sonar exposure.”
On Jan. 3, the Los Angeles-based judge issued a court order that increased the Navy’s surveillance for whales.
She ordered commanders to refrain from using powerful sonar within 12 nautical miles of the coast and in the waters between Santa Catalina and San Clemente islands.
She wanted the Navy to expand its safely zone for shutting down sonar and reducing sonar power under certain sea conditions.
Navy officials say the added restrictions greatly reduce its ability to train in realistic conditions.
They say the waters between Catalina and San Clemente islands present the same challenges as in the Persian Gulf’s Strait of Hormuz, for instance.
Cooper is expected to rule as early as this week on the Navy’s request that she lift all the restrictions, arguing that the issue is moot because President Bush exempted these exercises from the laws that formed the basis of the lawsuits.
California officials and conservation groups rebut this legal argument and have urged Cooper to uphold the ruling.