Only about one in four US F-35s was fully mission capable in fiscal year 2025, per the Government Accountability Office's June 11, 2026 review: the fleet's mission capable rate fell from 67 percent in FY2021 to 44 percent in FY2025, and the full mission capable rate from 38 percent to 25 percent. Lifetime sustainment costs are estimated at $1.6 trillion.
What did GAO find?
The report, GAO-26-108113, describes a fleet that has outgrown the system that supports it. The F-35 is DOD's most costly weapon system, GAO notes, and it has not met performance goals while sustainment costs keep increasing. Among the specific findings: DOD has handed its contractor hundreds of millions of dollars in incentive fees since 2020 to improve readiness, and those incentives have not been effective, per the June 11, 2026 report.
Variant detail sharpens the picture. Air and Space Forces Magazine reported that Air Force F-35As posted the highest full mission capable rate of the three variants but still reached only 28.5 percent in 2025, well below the service's 65 percent goal for that year. The magazine's account of the report attributes the decline to software issues, spare parts shortages, and corrosion. GAO's data series shows the slide has been continuous rather than episodic, with each fiscal year from 2021 through 2025 posting lower capability rates than the year before, a record that predates the current strategy.
What is DOD's response?
The department's answer is the Global Support Solution Reset, which GAO calls a positive step while pressing for more rigor. The strategy carries an estimated $13.7 billion more than previously planned through FY2031, and the program office will rely on private-sector delivery of over $7 billion in additional parts. GAO's three recommendations, all open as of publication, direct the program office to build risk mitigation plans, redesign incentive approaches with penalties or adjusted thresholds, and install quality controls on incentive fee data. DOD concurred in draft.
Why does the report matter now?
The review lands in the middle of a budget season in which the department is asking for sustained growth, and sustainment is where the money actually goes. As Air and Space Forces Magazine reported on June 11, 2026, the program office says it remains focused on 2030 readiness goals under the reset. GAO's framing is narrower: without mitigation plans and honest incentive data, the goals rest on the same mechanisms that produced two decades of optimistic sustainment assumptions.
For Congress, the report supplies the line items to watch: parts funding, depot capacity, and the incentive fee structure. Each is auditable, and each has a documented history of falling short of stated targets.
