The Government Accountability Office (GAO) – the agency that provides auditing services for the U.S. Congress – has criticised the Pentagon’s plans for Block 4 of the F-35 Joint Strike Fighter programme. The funding needed for this effort is projected to be nearly $3bn over the next 6 years, which, the GAO notes, would qualify it as a major defence acquisition programme in its own right.

The GAO is not comfortable with the fact that the DoD does not currently plan to manage Block 4 as a separate programme with its own baseline but rather as part of the existing baseline. As a result, Block 4 will not be subject to statutory and regulatory oversight requirements, such as providing Congress with regular, formal reports on programme cost and schedule performance.

According to the GAO, best practices recommend an incremental approach in which new development efforts are structured and managed as separate acquisition programmes with their own requirements and acquisition programme baselines. Therefore, the Agency notes, it will be difficult for Congress to hold DOD accountable for achieving its cost, schedule, and performance requirements.

The GAO notes that, although the F-35 total programme acquisition costs have decreased since 2014, the programme continues to face significant affordability challenges. DoD plans to begin increasing production and expects to spend more than $14bn annually for nearly a decade on procurement of F- 35 aircraft. Currently, the programme has around 20% of development testing remaining, including complex mission systems software testing, which the GAO describes as challenging.

According to Reuters, Lieutenant General Chris Bogdan, who heads the F-35 Joint Program Office (JPO), rejected the call to make the $3bn project into a separate weapons programme.

In a separate report, the GAO declared that Pratt & Whitney's F135 engine for the F-35 was still "not performing at expected levels". Though the report acknowledges that recent design changes have resulted in reliability improvements, it states that "the F-35A and F-35B engines are still at about 55% and 63%, respectively, of where the programme expected them to be at this point”.