from:starbulletin.com/2006/03/19/news/story10.html

Enemy subs a tricky target
Increasingly complex exercises train the Pacific Fleet to detect quiet new diesel craft
By Gregg K. Kakesako
[email protected]

SEVENTY-FIVE MILES SOUTH OF OAHU » For nearly seven hours, Navy Lt. Cmdr. Bill Perkins and his Kaneohe Bay-based P-3 Orion sub-hunting aircraft spent the night participating in an anti-submarine chess game.


GREGG K. KAKESAKO / [email protected]
As a P-3 Orion sub hunter flight technician, Petty Officer Heather Gildersleeve is responsible for launching sonobuoys, which weigh from 10 to 30 pounds and relay information about vessels in the area to central computers.

The mission of his Patrol Squadron 4 Skinny Dragons was to keep submarines away from the high-value target presented by the USS Lincoln aircraft carrier and its 75 combat jets. Other Orion squadrons participating in the anti-submarine warfare exercise that ended Tuesday were Kaneohe Bay's VP-9 Golden Eagles and VP-46 Grey Knights from Whidbey Island Naval Air Station in Washington.

They were part of a picket line of defensive planes, helicopters and warships practicing the skills they need to locate and hunt a new generation of quiet diesel subs.

Further to the west, a wintery storm picked up momentum. The high seas, high winds and rain from the storm added another complication to the hunt.

With more than 140 quiet, diesel-electric subs belonging to countries like North Korea, China and Iran, Adm. Gary Roughead, commander of the Pacific Fleet, has made it mandatory that ships in a carrier or amphibious strike group undergo three days of intensive anti-submarine warfare in waters off Oahu before deploying to the western Pacific.

The U.S. Navy has 50 nuclear-powered subs split between the Pacific and Atlantic theaters, but no diesel subs. The Heritage Foundation has said that China has 70 diesel subs, North Korea 26 and Iran six. They carry torpedoes, cruise missiles and mines, like nuclear subs, and can hide in strategic points in the Taiwan Strait or the Strait of Hormuz in the Middle East, operating quietly on battery power.

While the Navy has no diesel subs to contribute to the exercises, its nuclear subs, like diesels, have magnetic signatures and other vulnerabilities that can be detected with airborne and seaborne sensors.

Two years ago the Pacific Fleet, then under the command of Adm. Walter F. Doran, formed the Fleet Anti-Submarine Warfare Command at Point Loma in San Diego, in recognition of the need for increased emphasis on anti-submarine warfare.

"When I look at the threats we may face in the 21st century, one emerging challenge is the improved diesel submarine technology and the threat that technology poses," Doran said at the time. "Anti-submarine warfare is a Navy core competency which needed a reinvigorated focus. We have recognized that we must take positive action and reorganize to meet this challenge ... and (it is) why I have made ASW as my No. 1 war-fighting priority."

Navy officials say the three-day exercise is like the last hurdle in a graduate-level war-fighting course.

The first three-day exercise was held in January with the aircraft carrier USS Reagan strike group, and continued last month with the USS Peleliu amphibious strike group, whose crown jewels were not jet fighters and bombers, but 2,200 Marines.

Rear Adm. Jay Donnelly, Roughead's deputy, who flew out to the Lincoln on Monday to assess the training, said much has been learned from the two previous training cycles.

The first two training exercises resulted in a more complex one for the Lincoln strike group, Donnelly said.

The two-star admiral said the number of "opposing force" Los Angeles-class nuclear-powered submarines was increased from one to three -- the Pearl Harbor-based USS Pasadena, USS Greeneville and USS Tucson.

The admiral said that for the next several months Pacific Fleet officials "will pore over the data to try and get a very honest assessment of how it went."

LT. JESSICA CLEARY, undersea warfare office for the VP-4 Skinny Dragons, coordinated the operations of the Kaneohe Bay's P-3 Orions for last month's exercise with the Peleliu.

She said one of the things that came out of the Peleliu exercise was the need "to fine-tune" the communication and coordination between aircraft and crews of the P-3s, helicopters and ships involved in the hunt for diesel submarines.

Cleary said the nine-member Orion sub hunter crews have four means of finding subs:

» A 15-foot ASQ-81 magnetic anomaly detector, basically a sensitive metal detector that sits at the tail of the aircraft.

» Sensitive radars that can detect the motion of a sub underwater, as well as other radar systems that seek out the electronic frequencies emitted by the radars of other ships.

» Sensitive video cameras and electronic optics that provide pictures and identifications of ships on the surface.

On Monday night, Perkins' crew dropped 50 of the 84 2 1/2 -foot sonobuoys it normally carries in the hunt to find the three submarines. A microphone is attached to the buoy with a string.

Information is relayed to computers on the aircraft, where technicians are able to distinguish whether a vessel in the area is a merchant ship or a submarine.

"Each ship design has an inherent sound signature," said Perkins. Besides sonobuoys, a P-3 Orion can be equipped with mines and torpedoes or anti-surface warfare Slammer, Maverick, Harpoon and Rockeye missiles and MK-80 bombs.

Similar sonobuoys and torpedoes can be dropped by helicopters flying off cruisers, like the 567-foot San Diego-based Mobile Bay, whose sole job is to protect the Lincoln.

The hull-mounted sonar at the front of the Mobile Bay ship and its two helicopters allow the cruiser to detect and destroy submarines more than 100 miles away.

On Monday, Capt. Thomas Carney, Mobile Bay's skipper, told reporters as he monitored the underwater hunt from his combat information center that since the exercise began on Sunday a picket line of helicopters, P3-Orions and his ship and two frigates had been able to track "some of the submarines."

"We are trying to locate him and keep as far away from the aircraft carrier as possible," Carney said. "The best defense is to keep as far away as possible."

Donnelly said diesel electric submarines are "quieter and harder to find. It's a skill that our sailors need to practice in order to maintain proficiency."

He added that the primary target in the Cold War were Soviet nuclear submarines, which were faster and noisier and spent all their time in deeper waters.

Perkins said a diesel sub works in shallower waters and needs to poke its periscope above the ocean surface to replenish its air supply and recharge its batteries.

He added that time is on their side in the game to outwit their underwater adversaries.

"We don't always know where the sub is," Perkins said, "but we know what their goals are, and we can just sit out there and just wait for him."

Doesn't Canada have some diesels that could participate?

The US has leased out a Swedish boat to San Diego to practise on.

NTM