The Navy delivered its first DDG 51 destroyer in April 1991, and 62 ships currently operate in the fleet. Two shipbuilders (Bath Iron Works Corporation in Bath, Maine, and Huntington Ingalls Industries in Pascagoula, Mississippi) build DDG 51 destroyers, with four separate configurations in the class (Flights I, II, IIA, and III) that reflect upgrades over the last 25 years to address the growing and changing capability demands on the Navy’s surface combatants. Table 1 provides details on each DDG 51 configuration. In 2007, the Navy determined, based on its Maritime and Missile Defense of Joint Forces (MAMDJF) Analysis of Alternatives, that a larger, newly- designed surface combatant ship with a very large radar was needed to address the most stressing ballistic and cruise missile threats. In response to the MAMDJF Analysis of Alternatives results, the Navy initiated development of a new cruiser, known as CG(X), and AMDR (SPY-6)—an advanced, scalable radar with a physical size that can be changed as needed to respond to future threats. Subsequently, in 2008, the Navy expressed an increasing need for greater integrated air and missile defense capability. Noting that DDG 51 ships demonstrated better performance than DDG 1000 ships for ballistic missile defense, area air defense, and some types of anti-submarine warfare, the Navy determined to restart production of DDG 51 Flight IIA ships to combat the increasing ballistic missile threats. In January 2009, USD (AT&L) issued a memorandum stating that the Navy’s plan to buy additional DDG 51 Flight IIA ships would be followed by a procurement of either DDG 1000- or DDG 51-based destroyers that could carry the SPY-6 radar. To fulfill this demand, the Navy conducted a limited study in 2009, referred to as the Radar/Hull Study, which examined existing DDG 51 and DDG 1000 designs with several different radar concepts to determine which pairing would best address the integrated air and missile defense needs at lower cost than the planned CG(X). Following the Radar/Hull Study, the Navy validated the need for a larger, newly designed surface combatant with a very large radar to counter the most stressing threats. However, based on the analysis of the Radar/Hull Study, the Navy decided to pursue a new DDG 51 configuration instead—now referred to as DDG 51 Flight III—that would include a new advanced, but smaller, radar and an upgraded Aegis combat system. The Navy also cancelled the CG(X) program. We found in 2012 that the Navy’s decision to pursue new DDG 51 destroyers equipped with a new air and missile defense radar represented a substantial commitment that was made without a solid analysis and that the planned oversight and visibility into the program was insufficient given the level of investment and potential risks. We also found that the Navy’s plan to buy the Flight III lead ship as part of an existing multiyear procurement of Flight IIA ships was not sound due to a lack of design and cost knowledge about the Flight III ships. Multiyear contracting is a special contracting method used to acquire known requirements for up to 5 years if, among other things, a product’s design is stable and the technical risk is not excessive. Based on our findings, we recommended that 1) the Navy complete a thorough analysis of alternatives for a future surface combatant program; 2) DOD increase the level of oversight for DDG 51 Flight III by changing the program designation to acquisition category (ACAT) 1D; and 3) the planned fiscal year 2013 DDG 51 multiyear procurement request not include a Flight III ship. Subsequent to our recommendations, the DDG 51 program was elevated to ACAT 1D status—with Flight III remaining an upgrade within the overall program—but a new analysis of alternatives was not undertaken and the fiscal year 2013 DDG 51 multiyear procurement was awarded as planned, with the Navy intending for the lead Flight III ship to be part of this procurement. The two existing DDG 51-class shipbuilders—Bath Iron Works and Huntington Ingalls Industries—will complete design changes to the existing DDG 51 hull form to support Flight III configuration needs and will construct the ships. In February 2015, the Navy modified its existing design contracts with the shipbuilders to begin Flight III detail design work, with initial construction planned for 2018. The detail design process, as shown in figure 1, begins at a high level for the overall ship. As the needs for the ship are better defined, the granularity of the design for individual units, or zones, of the ship comes into focus. The shipbuilders use computer-aided design product models to design the ship. The product models generate a detail design, which allows engineers at the shipbuilders to visualize spaces and test the design. This validates elements of the design prior to construction, thereby avoiding potentially costly rework. During product modeling, the designers finalize the interfaces between zones, complete the design for ship-wide cables and pipes, and add all detail necessary to support ship construction. The Navy reviews the progress of each zone when it is 50 and 90 percent complete with product modeling. At these critical reviews, the Navy and other stakeholders assess the zone design progress and provide input to ensure that the design meets specifications. Once a zone is 50 percent complete, more detailed design tasks are undertaken by the shipbuilders to finalize and incorporate all outstanding data from the key systems. When the zone is 90 percent complete, it is essentially considered to be finished with detail design, and the shipbuilder will subsequently convert the design into drawings to support construction. The Navy’s AMDR program, which began development in 2013, will provide key IAMD capability for Flight III. The program includes engineering and manufacturing development of a new S-band radar— known as SPY-6—that is being executed by the Raytheon Company to provide volume search capability for air and ballistic missile defense. The radar is expected to have a sensitivity for long-range detection and engagement of advanced threats of at least “SPY+15”, referring to its improved capability compared to the current SPY-1D(V) radar used on existing DDG 51 ships. In addition, the contractor is developing a radar suite controller to provide radar resource management and coordination, and to interface with the Aegis combat system upgrades for Flight III. The Navy is leveraging an existing X-band radar—SPQ-9B—to provide horizon and surface search capabilities, as well as navigation and periscope detection and discrimination functions for the majority of currently planned Flight III ships. The Navy intends to develop a new X- band radar with improved capabilities that will be installed on later Flight III ships. Figure 2 depicts a notional employment of the S-band and X- band radars on a Flight III ship. Along with AMDR development, the Navy is working with the prime contractor for the Aegis combat system—Lockheed Martin—to upgrade the system for Flight III ships. Aegis, which integrates ship sensors and weapons systems to engage anti-ship missile threats, has been providing the Navy with some form of surface defense capability for decades. Over that time, the system has been regularly upgraded, with Aegis Advanced Capability Builds (ACB) providing new, expanded capabilities. The most recently completed build—ACB 12—provides initial integrated air and missile defense capability for DDG 51 Flight IIA ships. ACB 16 is currently in development and is expected to provide, among other things, new electronic warfare capability and expanded missile capability options. Flight III will incorporate ACB 20, a combat system upgrade that includes support for the SPY-6 radar. As with any DOD weapon system, test and evaluation activities are an integral part of developing and producing DDG 51 Flight III, AMDR, and Aegis systems. Test activities provide knowledge of system capabilities and limitations as they mature and are eventually delivered to the warfighter. Developmental testing is intended to provide feedback on the progress of a system’s design process and its combat capability as it advances toward initial production or deployment. For Flight III systems, developmental testing occurs at contractor or government land-based test sites, and will eventually expand to include testing of systems on board the ship after installation—known as shipboard testing. Operational test and evaluation is intended to assess a weapon system’s capability in a realistic environment when employed in combat conditions against simulated enemies. During this testing, the ship is exposed to as many operational scenarios as practical to reveal the weapon system’s capability under stress. The Navy’s operational test agency plans and executes operational testing for DDG 51 and AMDR, as well as other selected programs—such as Aegis. The Director, Operational Test and Evaluation (DOT&E) within the Office of the Secretary of Defense coordinates, monitors, and reviews operational test and evaluation for major defense acquisition programs. DOT&E’s statutory responsibilities include (1) approval of test and evaluation master plans and operational test plans for systems subject to its oversight, (2) analyzing the results of the operational test and evaluation conducted for such systems to determine whether the test and evaluation performed were adequate and whether the results confirm the operational effectiveness and suitability for combat, and (3) reporting the evaluation results of operational testing to the Secretary of Defense and congressional defense committees. The Navy’s AMDR program is progressing largely as planned toward final developmental testing of the SPY-6 radar. An extensive technology developmental phase for the new radar helped increase the maturity of critical technologies, thereby reducing risk prior to beginning the program.