The U.S. Government Accountability Office (GAO) is urging the U.S. Navy to delay procurement of the service’s Flight III version of the long-serving Arleigh Burke-class (DDG-51) destroyer. The new destroyer subclass will replace the original SPY-1 phased array radar with an advanced SPY-6 gallium nitride-based active electronically scanned array (AESA) radar—which will be many times more powerful. However, the new warship will require extensive redesign to accommodate the new radar and a host of other upgrades.

“The Navy has not demonstrated sufficient acquisition and design knowledge regarding its Flight III procurement approach and opportunities exist to enhance oversight,” reads an Aug. 4 GAO report titled Delaying Procurement of DDG 51 Flight III Ships Would Allow Time to Increase Design Knowledge. “If the Navy procures the lead Flight III ship in fiscal year (FY) 2016 as planned, limited detail design knowledge will be available to inform the procurement.”

The GAO also disputes the Navy’s cost estimates for the new ships, noting that the service has not updated those figures for the new Flight III design. “The Navy’s anticipated cost savings under the FY 2013-2017 Flight IIA multiyear procurement (MYP) plan do not reflect the planned addition of Flight III ships,” the report states. “While the Navy did not update its cost savings with Flight III information, doing so would increase transparency and could help inform expected savings under the next MYP.”

The GAO is concerned that the Navy intends to request authority for a multiyear buy for the Flight III destroyers without enough cost data. “The Navy plans to request authority to award new Flight III MYP contracts (FY 2018-2022) in February 2017,” the GAO stated in its report.  “The Navy will be asking Congress for this authority to procure nearly half of Flight III ships before being able to meet the criteria to seek this authority. For example, detail design will not be complete and costs will not be informed by any Flight III construction history.”

Perhaps more troubling for lawmakers will be the fact that under current program structure, Congressional appropriators will not be able breakout Flight III cost and schedule data from the rest of the DDG-51 fleet. “Flight III cost and schedule performance is not distinguished from that of the overall DDG 51 ship class in annual reports to Congress,” the report states.

To ensure transparency, the GAO is recommending that the Navy establish the new destroyer as a major subprogram with its own reporting requirements. “Establishing Flight III as a major subprogram would improve reporting and offer greater performance insight,” the report states.

Meanwhile, the Flight III effort seems to be moving along smoothly. “The Air and Missile Defense Radar (AMDR) program’s SPY-6 radar is progressing largely as planned, but extensive development and testing remains,” the report reads. “Testing of the integrated SPY-6 and full baseline Aegis combat system upgrade—beginning in late 2020—will be crucial for demonstrating readiness to deliver improved air and missile defense capabilities to the first DDG 51 Flight III ship in 2023.”

Dave Majumdar is the defense editor for the National Interest. You can follow him on Twitter: @davemajumdar.