New Attack Submarine:

More Knowledge Needed to Understand Impact of Design Changes

NSIAD-98-38: Published: Apr 30, 1998. Publicly Released: Apr 30, 1998.

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GAO reviewed: (1) the status of the new attack submarine (NSSN) development program; (2) current information on the antisubmarine warfare threat; and (3) the Navy's plans to model the NSSN's survivability.

GAO noted that: (1) since modeling the NSSN's survivability in 1995, the Navy, because of technical and funding limitations, has modified the design for some subsystems that reduce performance below the optimal levels used to model the 1995 baseline design; (2) other systems also have developmental problems; (3) at the same time, Navy threat assessments have reported that the open ocean antisubmarine warfare threat has improved, resulting in a more capable threat than previously projected; (4) the Navy tester's 1997 assessment report concluded that the NSSN could potentially be operationally effective and suitable, but noted a number of significant changes and risks in the development program; (5) the report also noted several technological advances in the open ocean antisubmarine warfare threat; (5) in addition, the report stated that budgetary pressures resulted in tradeoffs in some of the performance modeled in the NSSN milestone II cost and operational effectiveness analysis and the tester's 1995 early operational assessment; (6) as of November 1997, the Navy program manager planned no additional survivability modeling to test the NSSN with its potential for reduced performance against the improved threat; (7) however, as a result of its 1997 assessment, the Navy tester recommended that the Navy develop a new modeling baseline that reflects the reduced performance of some subsystems and that this new design baseline be evaluated against the increased threat; and (8) without such modeling, the Department of Defense and Navy program officials appear to have little basis for their confidence that the currently designed submarine will perform as expected.

Recommendations for Executive Action

  1. Status: Closed - Not Implemented

    Comments: Five submarines are currently under construction. Recommendation on design of submarine is now moot.

    Recommendation: To avoid spending funds on construction from a design that may require costly modifications to meet requirements, the Secretary of Defense should require the Secretary of the Navy to conduct survivability modeling to assess the impact that reduced capabilities of various subsystems have on ship survivability when integrated into the overall NSSN design.

    Agency Affected: Department of Defense

  2. Status: Closed - Not Implemented

    Comments: Recommendation is tied to implementation of another recommendation.

    Recommendation: The Secretary of Defense should take steps to ensure that the results are used in making fiscal year spending decisions on the program.

    Agency Affected: Department of Defense


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