Sunday Ship History: Airborne Mine Sweepers

"[W]e have lost control of the seas to a nation without a Navy, using pre-World War I weapons, laid by vessels that were utilized at the time of the birth of Christ."

Sea mines and the war in Korea, in the early days of 1950:

The UN command was fortunate that it did not have to deal with enemy minefields in the first critical months of the war, because the allied navies did not have adequate mine countermeasures resources. Owing to post-World War II demobilization and defense budget cuts, the wartime force of 500 mine warfare vessels, manned primarily by Naval Reserve sailors, had been reduced to a worldwide contingent of two destroyer minesweeper divisions, two fleet minesweeper divisions, and 21 smaller craft. During the postwar years the Navy devoted much more of its attention and resources to the development of new aircraft carriers, jet aircraft, and shipboard surface-to-air missile systems than mine warfare ships and equipment.

However, following the Inchon invasion, things changed and various sea mine incidents caused the deaths of number of allied sailors including the loss of USS Magpie with 33 men. Then mines became the "show stopper" for the next big amphibious invasion off Wonsan:

...[A]n armada of 250 warships and transports, the latter carrying 50,000 marines and soldiers of the U.S. X Corps, waited idly offshore as minesweepers worked to clear an approach route through waters containing over 3,000 mines laid with the direct assistance of Soviet advisors.

It was challenging:

On October 10, Captain Richard C. Spofford's Mine Squadron 3, warned by the helicopter crew from U.S. cruiser Worcester that mines were present in the waters off Wonsan, began their dangerous clearance mission. During that day and the next two, Spofford's nine vessels, helped by helicopter and PBM seaplane spotters, cleared a twelve-mile-long lane toward the landing site. The ships neutralized over 30 mines while the men of Underwater Demolition Team 3 marked another 50 mines for later destruction. In mid-morning of the 12th, however, minesweeper Pirate (NB Eagle1: Remarkable set of photos of Pirate hitting the mine and sinking can be found here) hit a mine and quickly sank, with six of her crewmen, and an hour later Pledge and six of her sailors met the same fate. Enemy shellfire from shore addded to the danger and difficulty of the operation. By the 18th, two days before the planned landing, the minesweeping force had almost cleared all moored contact mines from the approach lane to the beach. That day, however, magnetic influence mines destroyed ROKN YMS 516 and half of her crew. Discovery of these new weapons stalled the operation. Finally, on October 25th the way was clear for the X Corps to deploy ashore at Wonsan. The operation, however, would be a non-combat "administrative landing," since Republic of Korea ground units had liberated Wonsan on October 11.

At one point Rear Admiral Allan Smith, in charge of the advance force at Wonsan, cabled the Navy's Washington headquarters that "we have lost control of the seas to a nation without a Navy, using pre-World War I weapons, laid by vessels that were utilized at the time of the birth of Christ." His words and the experience at Wonsan would engergize the Navy's mine warfare community.

Well, given that we seem to keep having to re-learn the lessons of Wonsan, it is unclear exactly how "energized" the Navy (other than the mine warfare community) was. On the other hand, among the nuggets found in the report is the report of the first use of helicopters in mine countermeasure operations. A less formal report of the first airborne mine operations can be found in the memory of LCDR Earl R. Bergsma as set out here:

In the autumn of 1950, helos were used primarily for SAR, observation and VIP transport. On October 1, 1950, the wooden-hulled minesweeper Magpie was sunk by an anchored mine off the Korean coast. While searching for survivors HU- Is LT Swinburne photographed two moored mines. Two days later Aviation Pilot Chief B.D. Pennington, also from HU-1, sighted several moored mines in the Wonsan area. From that point onward, helos had a new mission, mine warfare. The Navy had ordered nearly all of its H03Ss from its two helo squadrons, HU- I (NB E1: HU-1 has a good historical website here)and HU-2, dispatched to Korea. Wonsan Harbor was the key mining area.

If the sea wasn't rough, if the direction of the sun rays was right, if the water was clear, and if the pilot was wearing polaroid sun glasses, he could spot the mines from aloft rather easily.
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Aviation Chief Pilot R. Jenks and a maintenance crew of six from HU- I were temporarily attached to several ships during our eight-month Korean tour. We were on USS St. Paul (CA-73), USS Toledo (CA- 133), USS New Jersey (BB62), USS Essex CV-9) and several LST amphibious landing craft. The LSTs were "mother" ships providing fuel, fresh water and mine sweeping tackle to the smaller wooden minesweepers. They also served as a small aircraft carrier for helicopters.

While aboard LST Q007 on May 6, 1951, the Senior Destroyer Commander radioed for our help. Two floating mines were sighted in the midst of his four anchored destroyers. The ships couldn't fire at them for fear of damaging each other. Aviation Mechanic Chief Slavin was our best rifleman so with our one and only Garand 30 caliber weapon he and I went hunting. As I hovered the H03S a safe slant range away, Chief Slavin shot and sank one of the mines. (In mine warfare school we learned that horned sea mines have an unactivated wet cell battery. When a horn is broken, by contacting a ship or from concusision, water enters the battery. Water mixes with acid and activates the battery, thus creating an electric charge which detonates the mine's explosives. If a mine's casing is penetrated, without breaking a horn, it fills with water which soaks the explosives and sinks without detonation.) He then fired repeatedly at the second mine until he ran out of ammunition. We dispensed dye marker to mark the spot, flew back to St. Paul for more ammo, and returned to the scene.
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Chief Slavin fired many times again at the mine, without result. I know damn well you're hitting that son of a gun' " I shouted, "Let's take a closer look." I eased the bird forward toward the mine and suddenly, with all his strength, the Chief yanked my shoulder back. "It's boiling," he cried. I stopped in time as the mine exploded, raising a column of water 200 feet high. Seconds later, six more underwater mines exploded, presumably from the concussion of the first one. One of the six was directly below the HOS3 and although it created a great upheaval of water, it didn't harm us except we felt the concussion.

We painted eight more mines on the side of our chopper that day. As a result of this and similar successes, it was recommended that helos be used in future eradication of floating mines: Our unit had shot and sunk two more mines when, unfortunately, a dispatch from higher authority was issued to all Naval Forces Far East. It said, "Helicopters will not (repeat) will not attempt to destroy mines in the future." The powers above apparently didn't want aircraft shot down by a mine. Thereafter, we assisted the minesweepers by dropping dye marker on the mines we sighted which were in the path of the minesweeper formations.

In this instance, however, the lessons of Korea were not completely lost. The Navy continued to experiment with mine sweeping by helicopters, as is well documented here (photos showing the "flying banana" and the RH-3A are borrowed, with appreciation, from that site):

The concept of Airborne Mine Countermeasures (AMCM) was initiated by the Bureau of Aeronautics in 1951, and research and development (R&D) to exploit the capability of the helicopter to participate in MCM operations was significantly expanded. This R&D effort in AMCM continued throughout the Korean and Vietnam conflicts as various helicopters were examined for suitability in the MCM role. Towed moored, magnetic, and acoustic sweep equipment was also developed specifically for the helicopter.

In 1952, Piasecki HRP-1 flying banana's were tested in Panama city to demonstrate their potential as minesweepers. VX-1, the Navy test squadron at Key West, Florida, also tested Piasecki's new minesweeping equipment aboard the HRP-1. In order to reduce weight on these underpowered helicopters, the fabric skin of the aircraft was removed, and large donut shaped flotation inner tubes were attached to the remaining framework. The minesweeping trials were fairly successful, even though the aircraft looked quite ridiculous.
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In 1962, the Chief of Naval operations directed helicopters be converted for MCM development, training and eventual operational deployment. The twin-turbine, tandem rotor Boeing-Vertol HRB-1 or RH-46A was the aircraft of choice. Unfortunately, the U.S. Marine Corps (USMC) had more urgent need for the H-46's, so the Navy turned to the Sikorsky HSS-2, renamed SH-3A Sea King. In 1964, Sikorsky began converting nine SH-3A's to RH-3A's for AMCM.
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Admiral Zumwalt, Chief of Naval Operations, began Project 60 in 1970. This project was the use of Airborne Mine Countermeasures as the principal means of clearing mines, based upon the sensitivity and sophistication of modern mines which precluded the use of surface minesweeping. The RH-53D Sea Stallion, a version of the CH-53A Sea Stallion was the selected successor as the AMCM platform. However, in an interim measure, the first AMCM squadron, HM-12 Sea Dragons, was formed in April, 1971 using fifteen CH-53A's borrowed from the USMC. As was the RH-3A, the CH-53A was similarly upgraded with AMCM specific enhancements.

As set out here in "Endsweep" by LtCol John Van Nortwick USMC, the Vietnam war prompted a revised interest in airborne mine sweeping, especially cleaning the U.S. dropped mines that closed the harbors of North Vietnam in 1972 and helped bring a close to the Vietnam war:

To counter this threat the Navy has developed the Airborne Mine Countermeasures (AMCM) program which transfers the surface mine clearance or countermeasures operation to an airborne platform, specifically the helicopter. The helicopter tows various devices thru the water of a minefield. These devices in turn cause the magnetic influenced mine and the acoustic mine to detonate in place. In the case of the moored contact mine, the device cuts it from its anchor allowing the mine to rise to the surface where it is detonated by small arms fire... Concurrent with the development of the mine countermeasures helicopter has been the attainment of a world-wide quick reaction capability. RH-53D or CH-53D helicopters, AMCM tow systems, and support personnel can be rapidly airlifted by C-5A to specific strategic areas considerably faster than previous surface mine warfare forces could deploy.
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In April 1971, a helicopter squadron, Helicopter Mine Countermeasures Squadron Twelve (HM-12), was commissioned at Norfolk, Virginia, and tasked with a primary mission of worldwide AMCM. The squadron functions under the operational control of Commander, Mine Warfare Force, Charleston, South Carolina. Initially, HM-12 was equipped with CH-53A's on loan from the Marine Corps. The helicopters were brought up to CH-53D specifications by Sikorsky Aircraft Corporation prior to commencing AMCM operations. The squadron is now equipped with the RH-53D, the primary minesweeping helicopter.

As that article indicates, on occasion, Marine H-53s were pressed into countermine operations. A description of sweep operations is also LtCol Northwick's article.

More recently:

The Navy had designed a new larger hydrofoil sled, the MK-166, and realized that even the RH-53D was underpowered to tow it. So in 1982, Sikorsky was awarded a contract to develop a new minesweeper, the MH-53E Sea Dragon. Based on the CH-53E Super Stallion, the first prototype of this three engine, seven bladed MH-53E helicopter was in fact a conversion CH-53E. It first flew in September 1983, and the first production aircraft was delivered to HM-12 in April 1987. It was decided that HM-16 would be disestablished in 1987, and key personnel would be taken to form HM-15 in Alameda, California, the first operational MH-53E squadron. The Naval Reserve received the RH-53D's displaced by the MH-53E's and formed two reserve AMCM squadrons, HM-18 in 1986 and HM-19 in 1989. Though the MK-166 sled was abandoned, the Sea Dragon has proven to be a valuable and powerful AMCM platform. Rated at 25,000lb maximum tow tension, the MH-53E eclipses the RH-53D (15,000lbs) and RH-3A (a mere 8,000lbs).

During Operation Desert Shield, HM-14 deployed six aircraft aboard USS TRIPOLI, then moving to USS NEW ORLEANS and USS LA SALLE. Most of the minesweeping missions in the gulf were MK-103 cutter arrays and MK-106 magnetic/acoustic sweeps. Toward the end of Operation Desert Storm the AN/AQS-14 sonar was successfully employed. During this period the helicopters also upgraded to Global Positioning System receivers for minefield navigation. Prior to this, the crews had to depend on less acurate and more complicated systems to determine their position in the minefield. The MH-53E's were usually trailed by SH-3 Sea Kings, SH-60 Seahawks, or UH-1N Twin Hueys which acted as mine spotters and carried Explosive Ordinance Disposal divers. AH-1J Cobras provided air fire support since the Sea Dragons have no armament (other than small .50 caliber machine guns) and have limited manueverability under tow.

Following Desert Storm, both AMCM squadrons (HM-14 and HM-15) went from 12 to 8 MH-53E aircraft, and the Naval Reserve squadrons upgraded from the RH-53D to the MH-53E. In 1992 the Commander, Mine Warfare Command assumed operational command of the AMCM squadrons. In 1994 and 1995, the Reserve AMCM squadrons were disestablished while Naval Reserve personnel and aircraft merged with the active duty squadrons to form two 12 aircraft integrated squadrons. In 1997, the USS INCHON (MCS-12)became operational as the Mine Countermeasures Command and Support ship. The HM squadrons received a dedicated platform from which they could launch AMCM missions from the sea.

Now the Navy is developing new helicopter resources:

The U.S. Navy intends to deploy the first MH-60S Knighthawk helicopters equipped with organic airborne mine countermeasures with carrier battle groups in 2005. (NB E1- but see here)

Although the service has not yet designated which carriers will receive the countermine equipment, planners expect forward-deployed helicopter sea combat squadrons with Sikorsky Knighthawks to replace dedicated helicopter mine countermeasures squadrons flying the MH-53E Sea Dragon. It takes 72 hours to airlift the big Sea Dragons and their minesweeping equipment to a combat theater. Multi-mission Knighthawks routinely operate from ships of many types.

"The beauty of the organic construct is that they're already in theater," observes Capt. James Rennie, the mine warfare branch head in the Expeditionary Warfare Directorate of the chief of naval operations.

The Navy will put new detection and neutralization technology on surface ships, submarines and aircraft. Seven new organic mine countermeasure programs are in development, five of which are helicopter based.
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The mine countermeasures console interfaces with sensors and with the GPS-assisted inertial navigator in the helicopter. It has a single large display that shows multiple views for each sensor and a smaller navigation display identical to those in the Knighthawk cockpit. According to Lockheed Martin director of multi-mission helicopter programs, Paul Monseur, “It’s one console for all sensors, one common look and feel for all of them.” Much of the console hardware is shared with the MH-60S/R common cockpit to facilitate maintenance, support and upgrades.

Block A systems operational on the Knighthawk in 2005 include the Raytheon AN/AQS-20 mine-hunting sonar and the Northrop Grumman Airborne Laser Mine Detection System (ALMDS).

The towed AQS-20 fish uses multiple sonars to scan large volumes of ocean quickly, and has an electro-optical imaging capability to detect and classify mines in one pass. ALMDS uses an aircraft-mounted LIDAR (light detection and ranging) sensor to detect floating mines and moored mines down to the keel depth of ships.

The common cockpit displays of the MH-60S and MH-60R remain unchanged, but additional software gives minesweeping crews tow tension and skew indicators. Mission plans generated aboard the ship will be downloaded into the aircraft on PCMCIA cards.

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Lockheed Martin received a contract in September 2003 to develop organic mine countermeasure systems on the MH-60S. The Block B capability in 2007 introduces the AN/AQS-232 AMNS (Airborne Mine Neutralization System) and RAMICS (the Rapid Airborne Mine Clearance System). The AN/ALQ-220 OASIS (the Organic Airborne and Surface Influence Sweep system) follows in 2008.

Derived from the German Seafox shipboard mine-neutralization system, the AMNS enables the MH-60S to relocate, identify and neutralize mines previously found by AQS-20 sonar, the ALMDS laser detector or other mine warfare platforms. The hovering helicopter deploys an expendable, self-propelled neutralizer steered to the suspected mine by the MH-60S operator. Sonar and video displays on the airborne console help identify a potential mine threat. Confirmed mines are destroyed or detonated with a shaped charge.

The RAMICS uses a laser-aimed 30 mm Bushmaster II cannon to neutralize near-surface, floating and shallow-bottom mines. The blue-green laser penetrates the water to target the mine for the stabilized, rapid-fire gun. Flat-nosed, super cavitating projectiles are designed to enhance range, speed and accuracy when entering the water. The high-velocity rounds penetrate the mine case and detonate the mine with a reactive charge.

The OASIS combines the acoustic and magnetic mine detonation functions now performed by noisemakers and magnetic sleds in a single towed body. Deployed from the helicopter, it emulates ship signatures in shallow water at speeds up to 40 knots.
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Countermine missions nevertheless will make additional demands on HSC crews. Today’s dedicated mine-warfare squadrons emphasize crew coordination and specialized pilot training. Air taxiing through sliding turns low above the water with minesweeping gear in tow takes practice.

More responsive, less-costly organic systems put additional demands on the MH-60S helicopter. Towing minesweeping gear inevitably takes a toll on aircraft. Mine countermeasures add about 300 pounds to the empty weight of the MH-60S, compromising performance in cargo and other roles. Sikorsky is studying weight reduction options, including composite stabilizers and lightweight crew seats.

With around 6,000 pounds sustained and 9,000 pounds peak tow tension and a comparatively small cabin, the MH-60S cannot use the Mk 105 sled or Mk 103 cutter array deployed with the MH-53E. However, OASIS, RAMICS and AMNS should provide operational commanders with new capabilities, and eliminate the need for explosive ordnance disposal divers to deal with mines cut loose by mechanical cutters. “It’s our intent to deploy a capability equal to or greater than the -53 capability,” says Rennie.

Sikorsky MH-60s website:

The MH-60S helicopter, in AMCM configuration, is equipped with five mine-hunting systems: AN/AQS-20 sonar, acoustic/magnetic minesweeper, remotely piloted anti-mine torpedoes, mine-detecting laser and 30mm mine-detonating cannon.

Airborne mine sweeping has come some distance from that early effort spawned by a couple of photos taken by a helo pilot off Korea. Let's salute the pioneers and the brave men who tow the sleds behind their aircraft, saving lives through their efforts. Let's hope we don't have to relive the painful times that gave rise to Admiral Smith's words that started this bit of history.

More information on Airborne Mine Countermeasures at Airborne Mine Countermeasures Website.

UPDATE: As noted in the comments, I did sail past the first airborne mine sweeping of real mines since the Korean War. As well set out in this Navy Postgraduate School thesis "Better Lucky Than Good: Operation Earnest Will as Gunboat Diplomacy
by Stephen Andrew Kelley, the U.S. was again caught with its mine countermeasures pants down:

The first American convoy operation commenced on July 22, 1987, when the 440,000 DWT crude oil tanker Bridgeton and the 46,000 DWT LPG (Liquid Propane Gas) tanker Gas Prince got underway in the Gulf of Oman and set course for Kuwait. The two recent additions to the American merchant fleet were escorted by the cruiser USS Fox (CG-33) and the guided missile destroyer USS Kidd (DDG-993). The small American convoy was supported by additional naval vessels positioned at the both ends of the Strait of Hormuz and off of Qatar.223 The USS Constellation (CV-64) battlegroup was stationed in the Gulf of Oman to provide aerial support. Saudi and American AWACS aircraft provided additional airborne surveillance over the Persian Gulf.
Following a safe passage through the Strait of Hormuz, the convoy anchored off Bahrain during the evening of July 23. On July 24, while underway approximately 20
miles west of Farsi Island, Bridgeton struck a moored mine. The mine damaged two forward cargo tanks, but did not result in any personnel injuries and the ship proceeded under her own power for Kuwait, with the thin-skinned U.S. Navy combatants trailing behind in an attempt to avoid sharing Bridgeton’s fate.
Iran denied responsibility for the attack, claiming the “hand of God” had holed the tanker. In fact, Iran had sown at least sixty mines in three areas.
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The mining of M.V. Bridgeton demonstrated American unpreparedness to combat the mine threat and, more importantly, exposed the fatuity of the assumption that Iran could be deterred from directly confronting the United States.
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Following the July 24 mining of M.V. Bridgeton Admiral Crowe ordered a halt to convoy operations until sufficient mine countermeasures platforms could be put into place. The United States Navy was forced to activate several 1950s-vintage Aggressive class minesweepers from the reserve fleet. As it would take time to tow the 30 year old wooden vessels from their stateside homeports to the Persian Gulf, an interim solution was required.
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The next major confrontation occurred on the night of September 21, 1987. Army special operations helicopters operating from USS Jarret (FFG-33) discovered the Iranian naval vessel Iran Ajr laying mines off Bahrain in an area used as an anchorage by Earnest Will convoys. The American helicopters attacked the small vessel with machine gun fire, forcing the Iranian crew to jump overboard. A United States Navy SEAL team boarded the vessel at first light and discovered nine mines on the vessel’s deck, as well as a logbook revealing areas where previous minefields had been set. Surviving Iranian crew members were repatriated and Iran Ajr was eventually scuttled.

U.S. and allied surface minesweepers came into the gulf and helicopter mine hunting and sweeping also came into action in the form of HM-14:

n June 1984, HM-14 took delivery of the AQS-14 Mine Hunting Sonar and established the fleet's first operational airborne mine hunting capability. In August 1984, the squadron responded to a JCS directed rapid deployment order in support of operation "Intense Look" to conduct split site airborne mine countermeasures operations in the Gulf of Suez in support of the Egyptian Government, and in the Red Sea in support of the Saudi Arabian Government. During these operations the squadron earned the Navy Unit Commendation.

In August 1987, the squadron executed another JCS directed rapid deployment order operating off the USS GUADALCANAL (LPH-7) and USS OKINAWA (LPH-3) in the Arabian Gulf as part of operation "Earnest Will." During these operations, HM-14 was credited with the first live moored mines swept by a U.S. Navy unit since the Korean Conflict. As a result of superb performance in the hostile and extremely demanding environment of the Arabian Gulf, HM-14 received the Navy Unit Commendation and the Armed Forces Expeditionary Medal.

The book No Higher Honor by Bradley Peniston, tells the tale of USS Samuel B. Roberts taking a mine hit and her crew's heroic fight to save their ship.

During Operations Desert Storm, two other Navy ships took mine strikes causing millions of dollars of damage. The Navy "Lessons Learned" included:

MINE WARFARE. DESERT STORM again illustrated the challenge of mine countermeasures (MCM) and how quickly mines can become a concern. Because of the difficulty of locating and neutralizing mines, we cannot afford to give the minelayer free rein. Future rules of engagement and doctrine should provide for offensive operations to prevent the laying of mines in international waters. Our Cold War focus on the Soviet threat fostered reliance on our overseas allies for mine countermeasures in forward areas. The MCM assets of our allies--- on whom we have relied for MCM support in NATO contingencies for years --proved their mettle in the Gulf, both in Operation EARNEST WILL (during the Iran-Iraq war) and DESERT STORM. Both operations highlighted the need for a robust, deployable U.S. Navy MCM capability. We are undertaking a comprehensive review of both our mine countermeasures strategy and the readiness of our forces to ensure our ability to conduct independent mine countermeasures operations when required.

Some have argued that mine warfare is not a popular career path because it is too damn hard.