United States General Accounting Office

GAO Report to the Secretary of Defense

April 1998 NEW ATTACK

SUBMARINE

More Knowledge

Needed to Understand

Impact of Design

Changes

GAO/NSIAD-98-38

GAO United States

General Accounting Office

Washington, D.C. 20548

National Security and

International Affairs Division

B-277780 

April 30, 1998

The Honorable William S. Cohen

The Secretary of Defense

Dear Mr. Secretary:

The Navy plans to spend $64 billion to acquire 30 New Attack Submarines

(NSSN) over the next 18 years. According to the Navy, these purchases will

allow it to maintain its force structure goals and the current submarine

industrial base. As part of our efforts to assist in the oversight of major

weapon systems acquisition programs, we reviewed (1) the status of the

NSSN development program, (2) current information on the antisubmarine

warfare threat, and (3) the Navy’s plans to model the NSSN’s survivability.

We are providing the results of our review for your use in oversight of the

NSSN program.

Background The NSSN program is intended to address the Joint Chiefs of Staff

requirement for 10 to 12 new attack submarines with Seawolf level

quieting by the year 2012 and to maintain future force structure goals. In

funding the NSSN program, Congress expected the Navy to deliver a less

costly submarine than its predecessor, the Seawolf, without compromising

military utility. The NSSN is expected to be a highly effective multimission

platform capable of performing antisubmarine and antisurface ship

missions and land attack strikes as well as mine missions, special

operations, battle group support, and surveillance. The NSSN is also

expected to be as quiet as the Seawolf, include a vertical launch system,

and have improved surveillance as well as special operations

characteristics to enhance littoral warfare capability. While the NSSN is

expected to perform effectively against the most capable, open ocean,

nuclear attack submarine threat, it will be slower and less capable in

diving depth and arctic operations and will carry fewer weapons than the

Seawolf.

The Navy’s fiscal year 1999 budget request contained about $1.5 billion for

procurement of the second NSSN and $504.7 million for advanced

procurement of the third authorized NSSN. The Navy also requested about

$219 million for continued research and development activities. Public

Law 105-561

 appropriated funds and Public Law 105-852 provided

1

The Department of Defense Appropriations Act, 1998.

2

The National Defense Authorization Act for Fiscal Year 1998.

Page 1 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

authorization for the contractor teaming arrangement to build the first

four new attack submarines. The Navy has established performance levels

to ensure that the NSSN will have the capabilities to successfully conduct

its missions. Operational requirements documents are required for the ship

and its major subsystems. These documents establish the optimal

(objective) and minimal (threshold) requirements related to the

submarine’s performance. For the most part, according to the NSSN

program manager, the NSSN is being designed to meet a cost-effective

balance at a performance level that meets or exceeds minimum

requirements. The Navy is also establishing detailed technical

specifications for the design of individual subsystems.

To gain assurance that the designs of the submarine and its subsystems

will result in the submarine successfully performing its various missions,

the Navy requires that the Program Manager use computer simulations as

a principal tool to model the NSSN’s capabilities against existing and

potential threats. An example is the modeling performed for the June 1995

NSSN milestone II cost and operational effectiveness analysis. Based on the

results, both the Department of Defense (DOD) and the Navy believe the

baseline NSSN design satisfies military requirements. The Navy also seeks

assurance by requiring that weapon systems be tested and evaluated in

their anticipated operational environment and against the anticipated

threat. This mission is performed by the Operational Test and Evaluation

Force, which was established by the Secretary of the Navy to be the Navy’s

sole independent agency for these activities.

Results in Brief Since modeling the NSSN 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. Other systems also have developmental

problems. 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.

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. The report also

noted several technological advances in the open ocean antisubmarine

warfare threat. In addition, the report stated that budgetary pressures

resulted in trade offs in some of the performance modeled in the NSSN

Page 2 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

milestone II cost and operational effectiveness analysis and the tester’s

1995 early operational assessment.

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. 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. Without such modeling, DOD and Navy program officials

appear to have little basis for their confidence that the currently designed

submarine will perform as expected.

Changes Made in

Approved NSSN

Design and Potential

for More

Since the Navy modeled the NSSN in 1995, a number of subsystems in

development have encountered financial constraints and developmental

problems. These financial constraints resulted in modifying the design

requirements for some of the subsystems to reduce the performance

capabilities. Significant development risks are also present in other

subsystems that could further affect planned performance. The Navy’s

tester noted that many of the potential risks are the result of program

restructuring to mitigate the effects of internally directed funding cuts. He

expressed concern that the combined effects of the reductions in

performance and developmental risks may affect the NSSN’s operational

effectiveness.

Reduced Capability

Subsystems

The Navy has restructured two key NSSN subsystems—electronics warfare

and acoustic intercept. The Navy has also reduced or will reduce some

operational performance requirements to the minimum acceptable levels

for the NSSN to successfully complete assigned missions.

The electronics warfare system enables the NSSN to covertly monitor

intelligence targets and record electronics data. Because of internally

directed fiscal year 1998 funding cuts, some system capability was

removed. The reduced capability system will not meet the optimal

performance levels modeled in the 1995 assessment, but it is projected to

meet minimum levels. The Navy has established the detailed technical

specifications that will be important to meeting those projections but has

not approved all of the operational requirements documents.

Page 3 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

Public Law 105-56 provided increased funding to restore some of the

critical elements of the electronics warfare subsystem—such as specific

emitter identification, full implementation of precision radar band

direction finding, and interception of frequency-hopping communications.

Public Law 105-85 authorized the increase.

The acoustic intercept system provides defensive capability for the

submarine and according to a Navy official, is critical to its survival. Like

the electronics warfare system, the acoustic intercept system was

restructured because of fiscal year 1998 internal funding cuts. Although

the restructured system will have fewer capabilities than the original one,

limited computer modeling indicates that if the restructured system

performs as expected, there is no statistical difference in performance.

The question is whether the restructured system will perform as expected.

In the June 1997 operational assessment of this system, the Navy tester

noted several deficiencies in achieving required performance. (Detailed

information on these deficiencies is classified.) As a result, the Navy tester

recommended approval for only a single unit for backfit testing on 688I

class submarines and only one unit for release to support the first NSSN

contingent upon resolution of these issues.

Subsystems Experiencing

Developmental Problems

The submarine’s propulsor and external communications systems are

experiencing development problems. These problems, although not

unusual at this stage in a weapon program, present significant risks in

meeting performance requirements. Also, the design for the lower cost

alternative to the present towed array has not been approved, nor has a

contractor been selected.

The propulsor provides thrust to move the submarine through the water.

Cavitation3

 noise from the propulsor is critical to the ability of enemy

submarines or surface ships to detect the submarine and, consequently,

has a major impact on a submarine’s survivability and operational

effectiveness. Currently, there is no cavitation performance requirement in

the NSSN operational requirements document, but there are program office

cavitation design goals.

The Navy, through large-scale vehicle testing, determined that an interim

propulsor design did not meet the program office’s cavitation design goals.

As a result, it has developed two alternative designs that it began to test in

March 1998. To meet the lead ship NSSN production schedule, the Navy

3

The noise generated by the movement of the submarine’s propulsor.

Page 4 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

must select from these alternatives during the one remaining large-scale

vehicle test before a propulsor for the lead ship is produced. If the

alternative designs do not meet cavitation goals, the Navy plans to backfit

another redesigned propulsor on the lead ship.

The external communications system was restructured in August 1996 to

provide a cost-effective means of introducing commercial hardware and

software technologies in order to meet the NSSN development schedule and

operational requirements. This system consists of several components

such as the submarine high data rate antenna system, various radio

frequency receivers, imagery and teleconference video capability, and

internal data distribution systems.

Improvements in the data rate capability of the external communications

system depend on the high data rate antenna system and the amount of

satellite resources allocated to submarine platforms. As currently

designed, with a 17-inch antenna, the Navy tester noted that the

submarine’s system will only be able to process the required amounts of

data if all of the Navy’s current satellite resources are allocated to support

submarine communications. The Navy is attempting to establish a concept

of operations among satellite scheduling units that will allocate

appropriate resources to the deployed submarine. Program office officials

said the Navy has alternative ways to provide the required satellite

resources such as using different frequencies on satellites or leasing

commercial satellites.

In addition, the Navy has not completed an overall operational

requirements document for submarine external communication systems.

As such, the NSSN external communications system design has not been

finalized. These documents are required to ensure that the system

configuration is properly designed to meet minimum performance

requirements.

Status of TB-29 Towed

Array

The TB-29 towed array and its processing system are critical to NSSN

operations in detecting, tracking, and, if required, attacking a threat

submarine. This system enables the NSSN to hear acoustic noises made by

threat submarines. However, the Navy has determined that the current

TB-29 system is too expensive. Also, the contract for the current TB-29

expired in fiscal year 1997.

Page 5 GAO/NSIAD-98-38 New Attack Submarine
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The Navy is looking for a comparable system at a lower cost than the

TB-29 array. Navy officials told us that required technology is available

and that it is a matter of selecting a design and a contractor to produce the

system. They believe there is sufficient time to develop and procure a new

system to meet the delivery of the first NSSN. However, there is no

approved design for the new system. Some developmental funding has

been specifically identified. Navy officials said the Chief of Naval

Operations has fully supported completing the TB-29 follow-on

development and procurement in future years’ budget submissions.

According to the program manager, a request for proposal for the design

of a new array will be issued early in fiscal year 1998. The Navy expects to

award a contract for the development and production of the new array in

the third quarter of fiscal year 1998.

A More Capable

Threat Has Been

Defined

In April 1996, the Office of Naval Intelligence revised its classified

underseas threat assessment and noted several technological advances in

the open-ocean, antisubmarine warfare threat. Several improvements

resulting in a more capable threat were noted over the previous threat of

record, which the Navy used to model the survivability of the NSSN design

in the 1995 assessment. (Details of these improvements are classified.)

Facing a more capable threat, and without an increase in submarine

capability, the risk to the NSSN’s survivability is likely to increase.

Navy Does Not Plan

Survivability Modeling

of Changes in Design

and Threat

The Commander, Operational Test and Evaluation Force, conducted NSSN

operational assessments in April 1995 and again in January 1997. (Detailed

results of these assessments are classified.) The 1995 assessment was

conducted using computer simulated modeling of the baseline NSSN design

against the threat projected at that time. As a result of the 1995

assessment, the Navy tester expressed concern that if the NSSN were just to

meet minimum requirements for survivability, the NSSN may not be

operationally effective against the most capable threat that the Navy was

projecting at that time.

The 1997 assessment was based on a more limited amount of information,

such as changes outlined in budgetary documents, and did not include an

in-depth survivability modeling as was done for the 1995 assessment. The

Navy tester’s report noted reduced performance of several subsystems and

developmental problems in others that also will result in reductions in

planned performance. The report pointed out that many of the affected

Page 6 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

subsystems, such as the acoustic intercept system and the propulsor, are

necessary to support the NSSN’s operational effectiveness and survivability.

The Navy tester concluded that the NSSN could potentially be operationally

effective and suitable. However, he recommended that a new NSSN

modeling baseline be established to reflect more current information,

because the performance of some subsystems had been reduced below the

performance modeled in the 1995 NSSN milestone II cost and operational

effectiveness analysis and the April 1995 early operational assessment. The

tester also recommended that this new design baseline be evaluated

against the currently projected threat.

Navy program officials are cognizant of the Navy tester’s report but have

indicated that there are no plans to perform an updated survivability

modeling of the total system against the new threat. Navy program

officials told us that they have modeled, or plan to model, the performance

of individual subsystems instead. Program officials also stated that even at

the current reduced performance levels, the subsystems discussed will still

meet NSSN minimum requirements. However, the submarine’s survivability

has only been assessed using performance levels above the minimum

requirements.

Conclusions and

Recommendation

The combined effects of a more capable threat, the reduction of some

system performance requirements, and the risks inherent in new

development could affect the NSSN’s operational effectiveness. Without an

evaluation that reflects current conditions, DOD and Navy program officials

appear to have little basis for their confidence in how the submarine, with

its design changes, will perform. Given the complexities and uncertainties

in weapon system acquisitions, encountering performance problems

during the development phase is not unusual. At this point in the NSSN

program, using modeling tools to identify and correct problems that could

affect the system’s survivability, such as those described in this report,

would allow changes to be made in development schedules and funding

profiles at a much lower cost than if problems were identified later.

To avoid spending funds on construction from a design that may require

costly modifications to meet requirements, we recommend that the

Secretary of Defense 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. Available research and development funding could be

Page 7 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

used for this modeling. Further, we recommend that the Secretary of

Defense take steps to ensure that the results are used in making fiscal year

spending decisions on the program.

Agency Comments DOD provided written comments on a draft of this report, which are

reprinted in appendix I. DOD stated that it agreed with the recommendation

in our draft report to conduct sufficient survivability modeling to assess

the extent to which the NSSN will be fully capable of countering the threat

and meeting all its mission requirements. In its comments, DOD

acknowledged that the performance of some subsystems was reduced

below that used to model the survivability of the NSSN during the

milestone II cost and operational assessment and the 1995 early

operational assessment. DOD laid out the process by which it makes

decisions on what testing is needed and how the test results are used. DOD

offered, as an example, that design changes to the Acoustic Intercept

Receiver and to the Electronic Warfare Support Measures suites were

assessed and determined to have reduced performance. The program’s

management concluded that the reduced performance of these subsystems

would not compromise ship survivability and, therefore, no higher level

modeling was required. DOD also stated that operational assessments,

already scheduled for fiscal year 2000 on an interim basis and fiscal

year 2002 for a final report, will assess the impact on overall NSSN

performance of changes to the design, validated threat projection, and

demonstrated subsystem performance.

The intent of our recommendation, however, was to have DOD conduct

survivability modeling. As we point out in the report, until the cumulative

effect of subsystem changes, including reduced performance, on overall

ship survivability is modeled, it will not be known if the NSSN will perform

as intended. For example, while performance modeling indicates that the

restructured acoustic intercept system may perform as expected, this does

not answer the question of what impact the system’s reduced capabilities

have on ship survivability when integrated into the overall NSSN design.

Therefore, although important, individual assessments of subsystem

performance such as those conducted in the Janaury 1997 operational

assessment, do not provide information on overall survivability when they

are integrated into the overall submarine design.

Likewise, the second phase of operational testing discussed in our report

and scheduled to be reported on in fiscal year 2000 will not include an

assessment of the overall survivability of the NSSN at reduced levels of

Page 8 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

subsystem performance, unless explicitly requested and paid for by the

program sponsor. Program officials have no plans to do so. As we note,

the Navy rejected the recommendation in the January 1997 operational

assessment that a new NSSN baseline be established to reflect more current

information and be evaluated against the currently projected threat. Based

on our discussions with Navy officials, there is no indication that tests

scheduled for fiscal year 2000 will include an assessment of overall

survivability nor that the results of the tests will be used to make

modifications to the program. If the combined reduction of subsystem

performance is subsequently found to affect overall ship survivability, the

NSSN program could face expensive modifications or reduced capability.

Therefore, we have modified our draft report recommendation to clarify

what we meant by sufficient survivability modeling.

DOD concurred with our recommendation that the Secretary of Defense

take steps to ensure that the modeling results are used in making fiscal

year spending decisions on the program. DOD officials have stated that it

now plans to conduct comprehensive annual reviews of the NSSN program.

Scope and

Methodology

We analyzed Navy and DOD documents and studies such as the NSSN costand operational effectiveness analysis and discussed the status of the

NSSN’s acquisition with Navy program officials in Washington, D.C.; at the

Naval Undersea Warfare Center, Newport, Rhode Island; and the Naval

Surface Warfare Center, Carderock Division. We held additional

discussions with officials from the offices of the Chief of Naval

Operations; the Assistant Secretary of the Navy for Research,

Development, and Acquisition; the Secretary of Defense; and the Program

Executive Office for Submarines. We also discussed program acquisition

status with (1) representatives from Electric Boat Corporation, Groton,

Connecticut, and Newport News Shipbuilding and Drydock Company,

Newport News, Virginia; (2) the Supervisors of Shipbuilding at these

respective shipyards; and (3) representatives from Lockheed Martin

Federal Systems, Manassas, Virginia. In addition, we analyzed the threat

modeling and other testing results contained in the NSSN’s operational

assessments and discussed the results with representatives of the

Commander, Operational Test and Evaluation Force, Norfolk, Virginia.

Discussions on the capabilities of the projected submarine threat were

held with representatives of the Office of Naval Intelligence, the Defense

Intelligence Agency, and the Central Intelligence Agency.

Page 9 GAO/NSIAD-98-38 New Attack Submarine
B-277780 

We conducted our review between December 1996 and March 1998 in

accordance with generally accepted government auditing standards.

We are sending copies of this report to the four congressional Defense

committees, the Secretary of the Navy, and the Assistant Secretary of the

Navy for Research, Development, and Acquisition. Upon request, we will

make copies available to other interested parties.

Please contact me on (202) 512-4841 if you or your staff have any

questions concerning this report. Major contributors to this report are in

appendix II.

Sincerely yours,

Katherine V. Schinasi

Associate Director, Defense

 Acquisitions Issues

Page 10 GAO/NSIAD-98-38 New Attack Submarine
Page 11 GAO/NSIAD-98-38 New Attack Submarine
Contents

Letter 1

Appendix I 

Comments From the

Department of

Defense

14

Appendix II 

Major Contributors to

This Report

18

Abbreviations

DOD Department of Defense

NSSN new attack submarine

Page 12 GAO/NSIAD-98-38 New Attack Submarine
Page 13 GAO/NSIAD-98-38 New Attack Submarine
Appendix I 

Comments From the Department of Defense

Page 14 GAO/NSIAD-98-38 New Attack Submarine
Appendix I 

Comments From the Department of Defense

Now on p. 7.

Page 15 GAO/NSIAD-98-38 New Attack Submarine
Appendix I 

Comments From the Department of Defense

Now on p. 8.

Page 16 GAO/NSIAD-98-38 New Attack Submarine
Appendix I 

Comments From the Department of Defense

Page 17 GAO/NSIAD-98-38 New Attack Submarine
Appendix II 

Major Contributors to This Report

National Security and

International Affairs

Division, Washington,

D.C.

Richard J. Price, Assistant Director

Jack G. Perrigo, Jr., Senior Evaluator

New York /Boston

Field Office

Richard E. Silveira, Evaluator-in-Charge

Joseph Rizzo, Jr., Evaluator

Office of the General

Counsel

William T. Woods, Assistant General Counsel

(707217) Page 18 GAO/NSIAD-98-38 New Attack Submarine
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