Surveillance Towed-Array Sensor System (SURTASS)
The Surveillance Towed Array Sensor System (SURTASS) is an element of the Integrated Undersea Surveillance System, providing mobile detection, tracking, and reporting of submarine contacts at long range. SURTASS was developed and deployed in the early 1980s as the mobile, tactical arm of the IUSS, providing long range detection and cuing for tactical weapons platforms against both diesel and nuclear powered submarines. With the SOSUS Arrays being placed in a standby status (data available but not continuously monitored), SURTASS must provide the undersea surveillance necessary to support regional conflicts and sea lane protection.
Ocean Surveillance Ships conduct submarine hunting patrols and counter drug missions. Ships on Submarine hunting duty employ a towed sonar array. Data is transmitted from the ship to an acoustic processing site ashore via satellite. Stalwart class ships were designed to search for foreign submarines. Several have since been assigned as drug interdiction forces. Victorious class ships are built on a Small Waterplane Twin Hull (SWATH) design for stability at low speeds and in rough waters.
Existing baseline SURTASS suites on monohull-hull T-AGOS ships are being deactivated and T-AGOS 19 and 23 class vessels will replace them. The new vessels feature a small water-plane area twin hull (SWATH) design which provides quieting to enhance performance of the reduced diameter array and greater stability in high sea states for the LFA source array. T-AGOS 23 class ships are larger than T-AGOS 19 ships in order to handle the larger and heavier equipment for the LFA system. Original procurement was projected for up to five T-AGOS 23 class ships; the current program is in flux, but will certainly be more modest, due to extensive delays by shipyard problems with construction of the $60,000,000 lead ship whose delivery has slipped to the end of 1998. The SURTASS block upgrade will back-fit into T-AGOS 19 (currently with a baseline system) and will be the sensor suite (passive receive only) for T-AGOS 20 through 22. Eventually T-AGOS 19 through 22 will also have a capability to receive and process bistatic LFA signals.The current, or baseline, sensor is a long array of hydrophones towed by a dedicated non-combatant ship designated T-AGOS. There are two upgrades.
The SURTASS Block Upgrade has been installed on four SWATH-P T-AGOS ships and two Monohull T-AGOS. The remaining monohull received the Block Upgrade in FY 1997-1998.
- The SURTASS Block Upgrade expands the capabilities of this towed array passive acoustic data collection and analysis system installed on T-AGOS Monohull and SWATH-P ships. The block upgrade improves the passive-only sensor with advancements against quiet threats including improved sensitivity and signal processing and use of a reduced diameter hydrophone array. The upgrade adds the Reduced Diameter Array (RDA) and a Commercial-Off-The-Shelf (COTS) processing system to provide increased detection capability, more flexible and higher resolution spectrum analysis, and improved target bearing. A communication upgrade will provide additional UHF SATCOM voice and data connectivity between T-AGOS and tactical platforms.
- SURTASS Low Frequency Active (LFA) is the active adjunct to this towed array. The low frequency active (LFA) upgrade is a long-range active sonar designed to detect even quieter threats in the future. The LFA system includes a large source array for active transmissions and the array of the block upgrade as a separate receiver. In its final configuration, SURTASS LFA will include the block upgrade. LFA adds an active transmit array and handling system, power amplification and control systems, an active signal processing and display receive system, and an environmental analysis system to the SURTASS Upgrade. A prototype LFA system has been installed on a leased commercial vessel, Cory Chouest, and operated as an interim fleet LFA asset pending delivery of the T-AGOS-23/SWATH-A, which will be equipped with LFA. New smaller active-source technologies are also under investigation for potential applications in a Compact LFA (CLFA) system suitable for backfitting into existing SURTASS ships. These upgrades provide improved shallow-water operational capability in support of littoral warfare. Open system architecture provides expandability and flexibility while lowering procurement and life cycle costs.
Other SURTASS development efforts include: twin-line array processing, improved detection and classification/passive automation to counter quieter threats; additional signal processing and bi-static active capability; integrated active and passive operations; improved Battle Group support; and improved information processing.
SURTASS has experienced recent passive and active success against diesel submarines operating in shallow water. A prototype twin-line SURTASS array was tested during 1996 in a variety of locations around the world, with positive results. It is far superior to any other shallow-water passive towed-array system. SURTASS processing is being transferred to the AN/SQQ-89 towed-array sonar system to provide an immediate increase in detection capability without the need to modify or procure additional wet-end hardware. The minimum fleet requirement of eight SURTASS ships is funded through the FYDP.
Functional improvements are delivered to the Fleet in software "Builds". Build #1 (FY 95) includes source-set formulation and analysis tools, automated line trackers and nuclear source auto- detector. Build #2 (FY 96) includes wideband energy trackers, wideband/narrowband feature association, and diesel Full Spectrum Processing (FSP). Build #3 (FY 97) includes automated localization and tracking, diesel automated detection and twin-line integration.
SURTASS is a non-military program staffed by civilian "operations personnel" contracted to SPAWAR, who operate and maintain the mission equipment under the operational command of Commander Undersea Surveillance (CUS). The SURTASS equipment is primarily deployed in Auxiliary Oceanographic Survey ships (T-AGOS) that are staffed by civilian mariners under contract to the Military Sealift Command (MSC). The Military Sealift Command operates ships manned by civilian crews and under the command of a civilian master. These ships, indicated by the blue and gold bands on their stack, are "United States Naval Ships" vice "United States Ships" as is the case of commissioned ships.
SURTASS is comprised of a worldwide network of ship and shore systems designed to do undersea surveillance. This complex network of mission dedicated equipment and systems routinely requires replenishment, upkeep, maintenance, and service to be accomplished by IOSC resident personnel. To this end, several "remote" facilities have been established to provide "bases" of operation in support of the SURTASS mission. Although operations are based in Norfolk Virginia, SURTASS routinely operates from ports in Glasgow Scotland, Rota Spain, Yokohama Japan, Pearl Harbor Hawaii, Port Huneme California, and many other ports of opportunity. SURTASS's Pacific operations are coordinated from the IUSS Operations Support Detachment (IOSD) located at the facility within NRaD Activity, Pacific in Pearl City, Hawaii. SURTASS is greatly reducing costs by consolidating logistics support, using Non-Developmental Items and commercial hardware, and increasing operator efficiency through computer aided detection and classification processing.
General Characteristics, Stalwart Class
Builder: Tacoma Boatbuilding, Tacoma, Wash.
Power Plant: Diesel-electric, twin shaft, 1,600 shaft horsepower.
Length: 224 feet (68 meters)
Beam: 43 feet (13 meters)
Displacement: 2,262 tons (2,056 metric tons)
Speed: 11 kts (12.7 mph, 20 kph)
Ship:
USNS Stalwart (T-AGOS 1)
USNS Indomitable (T-AGOS 7)
USNS Prevail (T-AGOS 8)
USNS Assertive (T-AGOS 9)
USNS Bold (T-AGOS 12)
USNS Capable (T-AGOS 16)
Crew: 18 civilians and 15 Navy personnel
General Characteristics, Victorious Class
Builder: McDermott Marine, Morgan City, Lou.
Power Plant: Diesel electric, twin shaft, 1,600 shaft horsepower
Length: 234 feet (72 meters)
Beam: 94 feet (28 meters)
Displacement: 3,396 tons (3,087 metric tons)
Speed: 16 kts (18.4 mph, 29.6 kph)
Ship:
USNS Victorious (T-AGOS 19)
USNS Able (T-AGOS 20)
USNS Effective (T-AGOS 21)
USNS Loyal (T-AGOS 22)
Crew: 22 civilians and 12 Navy personnel
General Characteristics, Impeccable Class
Builder: American SB, Tampa, FL; and Halter Marine, Gulfport, MS.
Power Plant:4 Diesel electric, twin shaft, 5,000 shaft horsepower
Length:281.5 feet (86.6 meters)
Beam: 95.75 feet (29.6 meters)
Displacement:5,362 tons (4,875 metric tons)
Speed: 12 kts ( 14 mph, 22 kph)
Ship:
USNS Impeccable (T-AGOS 23)
USNS ______ (T-AGOS 24)
USNS ______ (T-AGOS 25)
USNS ______ (T-AGOS 26)
USNS ______ (T-AGOS 27)
Crew: 26 civilians and 19 Navy personnel
Sources and Resources
- Cetaceans Do Not Have Standing To Sue the Government to Challenge Navy Use of SURTASS / LFA, appeals court ruling in The Cetacean Community v. George W. Bush, October 20, 2004
- Navy completes first T-AGOS class ship littoral warfare upgrade March 10, 1999 -- SPAWAR is inserting the second generation of commercial-off-the-shelf (COTS) equipment into the SURTASS baseline. USNS BOLD recently became the first T-AGOS ship to complete this upgrade.
