MFTA: The US Navy’s New Towed Array for Naval Detection

Naval technologies have advanced on many fronts, but one of the most significant is the growing roster of diesel-electric submarines that boast exceptional quietness. Some of the newer AIP (Air-Independent Propulsion) models even have the ability to operate without surfacing for a week or two at a time. In exercises against the US Navy, diesel-electric submarines have successfully ‘killed’ their nuclear counterparts, and in 2006, a Chinese submarine reportedly surprised a US carrier battlegroup by surfacing within it.

The US Navy is slowly moving to beef up anti-submarine capabilities that had been neglected since the end of the Cold War, and other navies are also beginning to adjust. One of the first areas that requires attention is improved detection. That means wider coverage areas, longer baselines, better sonar and other detection systems, and greater use of small unmanned platforms on the surface and underwater. With UUV/USV platforms still maturing, and almost every advanced navy except the Chinese getting smaller due to the cost of new warships, towed systems are a natural place to start.

The New MFTA

In the USA, towed array systems are made by a number of manufacturers: EDO/ITT, L-3, Lockheed Martin Undersea Systems, and the small specialist firm Chesapeake Science Corp. are a few of the firms involved.

Unlike a ship’s main bow-mounted sonar, towed arrays can quickly be fitted to any ship with a minimum of yard work. Towed arrays will also be necessary adjuncts to future unmanned anti-submarine vehicles, as their low weight and streamlined shape makes them usable by smaller platforms. Hence MFTA (Multi-Function Towed Array) production contracts since 2008, which are replacing America’s existing set of AN/SQR-19 TACTAS arrays.

The new AN/SQR-20 (now TB-37U) MFTA is the first new surface ship array to be built for the U.S. Navy in 25 years, and is configured as a long 3″ diameter array that can be towed behind surface ships. It is an active and passive sonar sensor, meaning it can listen silently for enemy submarines, or can send out a an active sonar ping and listen for the echoes. MFTA provides several enhancements over the existing AN/SQR-19 TACTAS, including better coverage, better detection capability, and better reliability.

The new towed array will be integrated with AN/SQQ-89Av15 underwater combat systems that are being installed aboard Arleigh Burke Class guided missile destroyers and Ticonderoga Class missile cruisers as part of their planned upgrades. It’s also slated for use on DDG-1000 Zumwalt Class “destroyers” as part of the AN/SQQ-90 dual-and sonar, and aboard the Littoral Combat Ships as part of their Anti-Submarine Warfare mission package.

While the array is described as “towed”, it can still be helpful for the array to have some attached movement capability. One of the key technical issues faced by towed arrays is the fact that knowing the shape of the array in the water is critical to interpreting its results. Unfortunately, currents, maneuvers by the towing vessel, and a myriad of other factors can change the array’s shape in the water. Self-monitoring via a pinging device and listening “birds” clipped along the array (birds because they measure “time of flight”) is a commonly used approach to calculating the array’s shape, and some kind of monitoring approach will continue to be necessary.

Having a streamlined node on the end with some maneuvering ability of its own – a UUV, for instance – can still be quite helpful, allowing operators to adjust the array line’s shape so it remains more useful more often. The US Navy specifically declined to discuss any aspect along these lines, saying that towing characteristics and features were not for public release.

The other unmanned mobility option would be to expand coverage by attaching the relatively small arrays to unmanned vehicles, allowing a warship to cover a much larger area, and to use unmanned vehicles as quiet advance scouts.

Lockheed Martin has confirmed to DID that part of the MFTA contract included an option involving the Remote Multi-Mission Vehicle (RMMV) snorkeling unmanned surface vehicle (USV). RMMV was expected to have a significant role to play in anti-submarine warfare (as the WLD-1), but the US Navy decided to restrict it to LCS’ counter-mine warfare package. That still leaves possibilities aboard USN cruisers and destroyers, but unless the USV improves significantly, WLD-1 probably would be more of a position adjustment aid than a towing platform. Overall USV technology, on the other hand, is expected to improve significantly in the coming decades. It’s very likely that some kind of USV or UUV system will eventually be deployed with MFTA as an independent sensor set.

Contracts and Key Events

Unless otherwise noted, contracts are issued by US Naval Sea Systems Command in Washington, DC, to Lockheed Martin Mission in Liverpool, NY. The division’s name changes, but it’s the same maritime sensor group.

September 23/19: First Production Unit Fabrication The US Navy awarded Lockheed Martin a $24.7 million cost-plus-fixed-fee contract to develop the first production unit fabrication and qualification of the TB-37X Multi-Function Towed Array (MFTA) System. The legacy TB-37/U MFTA is an integral part of the AN/SQQ-89A(V)15 Undersea Warfare Combat System Improvement Program for the Arleigh Burke Class guided missile destroyers (DDG-51), Ticonderoga Class missile cruisers (CG-47) and Zumwalt Class destroyers. The TB-37X MFTA shall incorporate next-generation telemetry to mitigate reliability and obsolescence issues experienced with the legacy TB-37/U MFTA. The TB-37X will be deployed on additional platforms, including Littoral Combat Ship (LCS) and Next Generation Guided Missile Frigates (FFG(X)). Lockheed will perform work in Liverpool, New York; Millersville, Maryland; Marion, Massachusetts; Cleveland, Ohio; and Albuquerque, New Mexico, and is expected to be completed by October 2026.

June 4/19: Production Units and Accessories Lockheed Martin won a $29.3 million contract modification to produce TB-37 Multi-Function Towed Array production units, accessories, shipping products, and spare modules for anti-submarine warfare (ASW) operations aboard surface warships. The TB-37, part of the AN/SQQ-89(V) Undersea Warfare/Anti-Submarine Warfare Combat System, is a next-generation passive and active sonar receiver configured as a long 3-inch-diameter array that can be towed behind surface ships. It is for Arleigh Burke Class destroyers, Ticonderoga Class cruisers, the Littoral Combat Ships, and Zumwalt Class land-attack destroyer. It is able to operate at a variety of depths to enable surface warships to detect and localize enemy submarines attempting to hide in different ocean layers of varying temperatures and salinity. Lockheed will perform work in New York, Maryland, and Massachusetts. Scheduled completion date is in June 2021.

May 25/15: Lockheed Martin has been handed a $27.3 million option for seven TB-37 multi-function towed array (MFTA) production units, as well as auxiliary equipment and support services. The work and production will be split between the US Navy and Japan under a previous Foreign Military Sale. The TB-37 is a potent anti-submarine warfare sensor, with the system offering several enhancements to the AN/SQR-19 Tactical Towed Array System which it replaces. The TB-37 Multi-Function Towed Array is the first new surface ship array to be built for the US Navy in 25 years and is configured as a long array that can be towed behind surface ships for ASW mission sets.

May 19/14: +9. Lockheed Martin Mission Systems and Training, Liverpool, NY, is being awarded a $31.8 million contract modification, exercising options for 9 TB-37/U Multi-Function Towed Array (MFTA) production units, tow cables, electro-optical slip rings, drogues, and engineering services.

$30.1 million is committed immediately, using various FY 2014 US Navy budgets. Work will be performed in Liverpool, NY (66%), Millersville, MD (33%), and Marion, Massachusetts (1%), and is expected to be complete by July 2016 (N00024-13-C-6292).

March 15/12: A $14.95 million contract modification to produce and support of AN/SQR-20 MFTAs. The Pentagon release specifically mentions production for the AN/SQQ-89Av15 antisubmarine warfare combat systems on board modernized US Navy cruisers and destroyers.

Work will be performed in Syracuse, NY (60%); Baltimore, MD (20%); Cleveland, OH (14%); and Phoenix, AZ (6%). Work is expected to be complete by January 2014. Contract funds will not expire at the end of the current fiscal year (N00024-08-C-6282).

March 25/11: A $7.9 million firm-fixed-price, cost-plus-fixed-fee contract modification exercises an option to produce more AN/SQR-20 MFTAs. Work will be performed in Syracuse, NY (60%); Baltimore, MD (20%); Cleveland, OH (14%); and Phoenix, AZ (6%), and is expected to be complete by January 2013 (N00024-08-C-6282). See also Military & Aerospace Electronics.

March 24/10: A $12.2 million firm-fixed-price, cost-plus-fixed-fee contract modification exercises an option to produce more AN/SQR-20 MFTAs. Work will be performed in Syracuse, NY (60%); Baltimore, MD (20%); Cleveland, OH (14%); and Phoenix, AZ (6%), and is expected to be complete by December 2012 (N00024-08-C-6282).

Dec 17/08: Lockheed Martin-MS2 in Liverpool, NY received a $15.1 million firm-fixed-price, cost plus fixed fee option under an existing contract (N00024-08-C-6282) to produce and support MFTAs for the AN/SQQ-89Av15 antisubmarine warfare (ASW) combat systems.

Work will be performed in Syracuse, NY (60%), Baltimore, MD (20%), Cleveland, OH (14%), and Phoenix, AZ (6%) and is expected to be complete by December 2012. The Naval Sea Systems Command in Washington, DC manages the contract.

June 23/08: MFTA appears to be ready to begin production. Lockheed Martin announces a $10 million contract to produce and support MFTAs for the U.S. Navy’s AN/SQQ-89 Antisubmarine Warfare Combat System. Work will be performed at Lockheed Martin’s Syracuse, NY facility, in collaboration with Chesapeake Science Corporation in Millersville, MD. Lockheed Martin release.

Nov 21/07: A 3rd revision [PDF format] is made to the RFP. Several sections clarify the structure of the production options, and restate the government’s option not to exercise them if it so chooses. With respect to the issue of the drawings raised in the Nov 5/07 amendment, it adds this language:

“1. The Government may have some of the drawings available to it in a modifiable format and to the extent such drawings are available the Government will make them available after award, as a courtesy, upon request by the successful offeror. The Government, however, will be under no obligation to provide any such drawings at all or in a given time frame, nor will the Government be under an obligation to convert any drawings into a modifiable format.”

Nov 5/07: A revised RFP (Amendment 0002), includes questions and answers that indicate a serious controversy with one of the [unnamed] bidders, who believes the competition is not level:

“We have some serious concerns with respect to the referenced competition:

a. The competition is for a “winner take all” FFP contract [rest relates to numbers produced, Navy clarified]…

b. Our competitor, Lockheed Martin contributed to the design of the Engineering Development Model and the drawing package (their CAGE code appears on some drawings). The RFP states that the drawing package is being provided for information only, but also says that if a contractor uses a drawing package or design other than provided by the Navy it will be viewed as a risk. Hence, the Government is mandating a baseline system engineered by Lockheed Martin and allowing them to bid as a supplier…

c. The Navy has provided the drawing package, with some drawings missing, in PDF format. The selected contractor will have to re-deliver a production data package… We asked for the drawing package in CAD/CAM, i.e. modifiable format, but RFP Amendment 1 denied our request. We will be at a substantial cost disadvantage in that we will have to re-develop the entire data package, whereas Lockheed can proceed with the modifiable format they already have available.

[Complaints are also raised re: incomplete test data and drawing information]

It seems to us that we are at a disadvantage with respect to our competitor who constructed the original drawing package, has built and tested an array [for which limited data was provided to others], and has insight into the revised “informational” drawing package that is the only recognized low risk approach…”

The Navy’s response involved changes in only one area – that the drawing package information was provided for information only, and that contractors had to meet the government’s requirements. Which included either using the existing MFTA design, or providing an “in-depth comparison” with the Navy’s “informational design.” RFP, incl. amendment and Q&A.

Sept 15/07: The US Navy issues a Request for Proposal for the production of up to 75 Multi-Function Towed Arrays for the AN/SQQ-89A(V) 15 Antisubmarine Warfare (ASW) Combat System. This RFP and related files listed under solicitation number N00024-07-R-6217 are issued electronically, and some controversy ensues re: the way the competition was set up. FBO advance notice.

Additional Readings

* US Navy Fact File – AN/SQQ-89(V) Undersea Warfare / Anti-Submarine Warfare Combat System

* Global Security – AN/SQR-19 Tactical Towed Array SONAR (TACTAS)