The F-35 Lightning II’s full mission capable rate fell to 25% in fiscal year 2025, down from 38% in fiscal 2021, according to a Government Accountability Office report published June 11.
While the Pentagon has proposed a $13.7 billion updated sustainment strategy to reverse this trend, the GAO warned that its fiscal 2027 cost projections were calculated prior to Operation Epic Fury and fail to account for the heavy combat flight hours logged during the conflict.
The overall mission capable rate dropped from 67% to 44% over the same period. Air Force F-35As posted the highest full mission capable rate among the three variants at 28.5% in fiscal 2025, still below the service’s 65% goal.
The F-35 Joint Program Office (JPO) launched its Global Support Solution (GSS) Reset in June 2025. It targets an 80% mission capable rate and 65% full mission capable rate by 2030, requiring an additional $13.7 billion through fiscal 2031.
GAO flagged the cost projections as potentially understated. Fiscal 2027 estimates were finalized before Operation Epic Fury, the 40-day U.S.-Israel campaign against Iran that began February 28, 2026, and do not capture those additional flight hours. JPO officials told GAO readiness will likely worsen before improving, with gains not expected before late 2026.
Spare parts shortages, corrosion, and software delays tied to the Technology Refresh 3 (TR-3) upgrade drove the fiscal 2025 decline, Air Force officials told GAO. A 2025 Lockheed Martin study identified 48 parts the supplier base cannot produce in sufficient volumes, including canopies.
From 2020 through 2023, the JPO paid Lockheed Martin $114 million of $269 million in available incentive fees even as full mission capable rates stagnated or worsened. As of March 2026, the Pentagon had implemented 14 of 46 GAO F-35 sustainment recommendations since 2014.
“We have recently invested more than $2 billion in advanced funding to accelerate spare parts to increase readiness rates across the F-35 fleet,” a Lockheed Martin spokesperson told Defense News.
