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	Director, Operational Test & Evaluation
	FY98 Annual Report

SYSTEM DESCRIPTION & CONTRIBUTION TO JOINT VISION 2010

T-AGOS/SURTASS is an element of the Integrated Undersea Surveillance System, providing mobile detection, tracking, and reporting of submarine contacts at long range, thereby contributing to the operational concepts of full-dimensional protection through information superiority. 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 Block Upgrade improves the passive-only sensor with advancements against quiet threats including improved sensitivity, signal processing, and use of a reduced diameter hydrophone 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 and will be used as either a passive system or in one of two active modes of LFA: monostatic or bistatic receive.

Baseline SURTASS suites were originally installed on monohull-hull T-AGOS ships. All but three of these ships have been deactivated and T-AGOS 19 and 23 class vessels are replacing 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. The T-AGOS 23 class ship (T-23) is larger than the T-AGOS 19 ship 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; however, the current program is limited to just the first ship. The SURTASS Block Upgrade was back-fit into T-AGOS 19 and will be the sensor suite (passive receive only) for T-AGOS 20 through 22. Eventually T-AGOS 19 through 22 will have the capability to receive and process bistatic LFA signals.

IOT&E was completed in 1992 and 1993 using DOT&E approved test plans. The T-AGOS 19 SWATH platform was found operationally effective and suitable to support the SURTASS Baseline System. The platform was also found to be potentially operationally effective and potentially operationally suitable in supporting the SURTASS Block Upgrade system, which was installed and operationally tested in 1994. The Block Upgrade successfully met all sonar detection Figure of Merit requirements. Localization and tracking accuracy was satisfactory. While there were some deficiencies, the Block Upgrade System was found to be operationally effective and suitable.

In June 1996, SURTASS LFA participated in a major fleet exercise, RIMPAC 96, including the preparatory exercise, TEAMWORK NORTH. The LFA, installed aboard the R/V Cory Chouest, operated in the open ocean south of the Hawaiian Islands, with a U.S. battle group and ships from five allied Pacific nations. In conjunction with the exercise, COMOPTEVFOR conducted an OA and endorsed the use of Cory Chouest as an interim fleet asset pending the completion of the SWATH ship T-23. DOT&E concurred with this recommendation.

In TEAMWORK NORTH, the LFA system detected a foreign submarine while making a transit to the Hawaiian Island area. In RIMPAC 96, LFA performed effectively by detecting all designated exercise participants. The environmental impact of LFA has become a significant issue and data is now being collected to support an Environmental Impact Statement (EIS) for future use. There is growing concern that testing of all active acoustic detection devices in shallow water ranges may be at risk due to environmental considerations.

No operational employment of LFA occurred in FY98 while environmental testing of LFA was in progress. Unsuccessful completion of the EIS prevented LFA from being used during RIMPAC 98. SURTASS units did participate, (passive only), in the RIMPAC 98 exercise.

T&E planning documents do not reflect current program status and schedule. Completion of the LFA EIS and slippage in T-AGOS 23 construction are resulting in delays in the conduct of planned OT. T-23 was originally planned for delivery in December 1998 but is now estimated for an October 1999 delivery. This will result in a cancellation of the planned OA in 4QFY99 and a delay in the SURTASS-LFA OPEVAL on T-23 until the last quarter of FY00. A TEMP revision is underway to reflect these changes.