Full mission capable rates for the F-35 fleet fell from 38 percent in fiscal 2021 to 25 percent in FY25, the Government Accountability Office reported — a steep decline that the Pentagon now hopes to reverse with a $13.7 billion sustainment request.
GAO’s core findings on readiness and trends
The Government Accountability Office’s review, published June 12, 2026, found that the F-35 tri-variant program’s full mission capable rate — defined as an aircraft’s ability to meet all assigned missions — slipped from 38 percent in fiscal 2021 to 25 percent in FY25. The jet’s mission capability rate, measured by whether an aircraft can perform one of its designated tasks, dropped from 67 percent to 44 percent over the same period. GAO tied part of that decline to a lengthy delay for an upgrade called Technology Refresh 3, which previously froze deliveries.
Global Support Solution Reset and the $13.7 billion request
To halt the downward trend, the F-35 Joint Program Office launched a “Global Support Solution Reset” (GSS Reset) last year. The Pentagon is seeking an additional $13.7 billion spread across FY26 through FY31 to execute that plan. GAO, however, cautioned that the reset faces “multiple risks” to achieving its readiness targets even if the funding is provided.
Service budgets and affordability constraints: Air Force, Marine Corps, Navy
GAO reported that the services that operate the F-35 will need to provide a portion of the funding for the GSS Reset. The Air Force told GAO it could “likely afford the costs associated with the GSS Reset” for its F-35As. By contrast, officials from the Marine Corps and Navy, which operate F-35Bs and F-35Cs respectively, told the watchdog that “competing priorities” could “limit the extent” of their available resources. JPO officials also told GAO that sustainment funding gaps remain despite prior supplemental appropriations from Congress.
GAO additionally found that projected annual costs in the program’s mid-2030s “steady state” — when fleets will be larger and upgraded — increased over earlier estimates for all variants except the Marine Corps F-35C. GAO warned that while each service’s respective funding “may be expected to meet requirements,” “long-term affordability will remain a challenge” and could “potentially” jeopardize sustainment.
Industrial base risks: canopies, the F135 engine, and capacity limits
Even if money is made available, GAO highlighted risks in the industrial base. Production of the aircraft’s canopy has been previously identified as a leading reason for lagging mission capable rates. On the F135 engine, Pratt & Whitney and JPO representatives told GAO that “even with additional funding, there may not be enough industry capacity to meet demand” for parts.
Industry statements included a Lockheed spokesperson saying the company “recently invested more than $2 billion in advanced funding to accelerate spare parts to increase readiness rates across the F-35 fleet.” A spokesman for Pratt & Whitney’s parent firm RTX told GAO the company “is building on a strong operational readiness track record while investing to expand capacity,” noting that “over the past five years, Pratt & Whitney has invested more than $1 billion to expand and modernize F135 production and sustainment capacity” and that this “has significantly increased F135 engine output, increasing current F135 production rates by 20% over previous contract rates.”
Incentive fees, JPO record-keeping, and GAO recommendations
GAO found that millions of dollars in incentive fees previously paid to Lockheed “have consistently not incentivized the achievement of JPO and US military service readiness requirements.” The report said the JPO even lacked “accurate records” of incentive fees paid out between 2021 and 2023. GAO warned: “Until it ensures the future use of incentive fees better achieves the desired performance, JPO increases its risk of continuing to reward performance that does not help the program meet its goals,” and suggested alternatives such as penalties for poor performance.
GAO issued three new recommendations: establish risk-mitigation plans for the GSS Reset; improve incentive-fee structures; and implement a system to better track incentive-fee metrics and payment information. All three recommendations remained open at the time of the report. Separately, the JPO is planning a working capital fund to oversee spare-parts supply that the watchdog said would take effect “no earlier than October 2028.”
What this means for the Air Force, Marine Corps, and Navy
- Air Force: The service indicated it could “likely afford the costs associated with the GSS Reset” for F-35As; that posture shifts the immediate fiscal pressure toward sustaining larger fleets and higher flight-hour predictions in the mid-2030s.
- Marine Corps: Officials warned that “competing priorities” could “limit the extent” of available resources for F-35B sustainment, raising concern about long-term affordability and readiness targets tied to the reset plan.
- Navy: Like the Marines, the Navy signaled resource constraints for F-35C sustainment; GAO noted projected steady-state costs increased for most variants, heightening the stakes for Navy budgeting decisions.
GAO’s review frames a narrow, immediate choice for Pentagon planners: approve a roughly $13.7 billion, multi-year injection tied to a Global Support Solution Reset and risk confronting industrial-capacity limits and lingering incentive-fee problems, or confront continued declines in mission-capable rates as the program enters a more expensive mid-2030s “steady state.” The watchdog left three recommendations open and a clear calendar item — a JPO working capital fund “no earlier than October 2028” — that will be a barometer for whether institutional reforms accompany the cash infusion.
