The U.S. Navy retired its last Avenger-class mine countermeasures ships this week in Bahrain, ending a legacy of over three decades of service in the forward-deployed mine countermeasures mission as part of Task Force 55. The replacement ships, Independence-class littoral combat ships, have struggled to meet the requirements of operational mine countermeasures missions.
The final ship to be decommissioned, USS Devastator (MCM 6), wraps up a long-awaited transition from legacy hulls of the Avenger-class to new, cutting-edge equipment onboard Independence-class littoral combat ships. The transition from the Avenger-class to the Independence-class is heralded by the U.S. Navy and Pentagon as a much needed step towards modernizing the fleet, but the added complexities and failure points of the LCS MCM mission package is making the transition difficult.
The forward-deployed MCM littoral combat ships operate with MH-60S Seahawk mine warfare helicopters. Each embarked helicopter is equipped with the with the AN/AES-1 Airborne Laser Mine Detection System (ALMDS), a specialized suite used for shallow water mine detection. Embarked helicopters also operate with the AN/ASQ-235 Airborne Mine Neutralization System (AMNS), offering a safer method to counter-mine potential threats compared to traditional mechanical minesweeping with EOD divers.
The unmanned portion of the MCM mission module are Common Unmanned Surface Vessels (CUSVs) developed by Textron Systems. They are also known as the Fleet-class of USVs. CUSVs embarked during mine countermeasures missions carry an option of two different systems. One is the AN/AQS-20C, a forward-look and side-scan sonar capable of locating sea mines. The other is the Unmanned Influence Sweep System (UISS) which adds acoustic and influence sweep capability to the CUSVs deployed by LCS motherships.
One test of the MCM package on USS Tulsa (LCS 16), a ship that arrived in Bahrain in May for MCM operations, resulted in a runaway USV, according to one U.S. Navy official familiar with the testing. During that test, part of the tow bracket used to recover the mine countermeasures CUSV broke, leaving it unrecoverable.
Another nearby Navy ship rushed to retrieve the CUSV which was towed back to port.
Another point of concern is the current suite of sensors which are ineffective in locating mines in operational environments, leaving the MCM-equipped littoral combat ships with inadequate sensors and countermeasure platforms for turbid waters or deep waters. The sonars on the CUSVs are not a high enough resolution to identify specific threats. The lasers used on MH-60S helicopters require water that is not too turbid to operate in.
A core recommendation, with sense of urgency, was the fielding of high-fidelity sonars to replace the visual identification requirement.
According to the U.S. Navy official, there is much less room for error when it comes to the unmanned systems used for mine countermeasures. Each mission takes roughly four hours of maintenance pre-mission followed by one-and-a-half hours of calibration of GPS and sonar to reach acceptable accuracy for MCM missions. The rough estimate is six hours of pre-mission preparation before mine countermeasures can begin. In real-world scenarios, that time may not exist.
These concerns do not address the single points of failure in the LCS and MCM package, which make the package an extremely risk-prone platform for operations.
The platform lift on the LCS that moves equipment from the mission bay to the flight deck is a major operational point for equipping the MH-60S with ALMDS or AMNS. If the lift fails, the helicopter is combat ineffective. If the tow hook on a CUSV breaks, it is combat ineffective and must be towed back or recovered another way. If the Twin Boom Extensible Frame, used to lower CUSVs into the water, breaks, the entire MCM platform is inoperable and USVs cannot be launched for missions.
Three Independence-class ships, the USS Canberra (LCS 30), USS Santa Barbara (LCS 32), and USS Tulsa (LCS 16), are currently forward-deployed with these mission modules, replacing the legacy Avenger-class ships that have served in Task Force 55 for over 30 years. Naval News covered the limitations of the LCS MCM modules previously, highlighting the line-of-sight limitation that has since been overcome using Starlink. Other limitations mentioned have been deployed to the fleet without remedy as a stopgap to end use of legacy hulls.
