F-35 Sustainment: Actions Needed to Ensure Updated Strategy Improves Persistent Readiness Challenges
Fast Facts
The F-35 is DOD's most costly weapon system, but it hasn't met performance goals and costs to sustain the aircraft continue to increase.
In 2025, DOD launched a new $13.7 billion strategy to improve F-35 readiness by 2030. The strategy aims to address challenges we've identified, such as a lack of spare parts. However, we found that multiple issues could threaten its success—such as constrained industry capacity to meet increasing demand for parts.
DOD also paid its contractor hundreds of millions in incentives since 2020 to improve F-35 readiness, but these incentives haven't been effective.
Our recommendations address these issues.
An F-35B aircraft takes off from the flight deck of a ship near dusk.
Highlights
What GAO Found
Since 2021, F-35 sustainment costs have continued to increase, but the F-35 has not met performance goals and performance has trended down. Across the fleet from fiscal year 2021 through fiscal year 2025:
- The mission capable rate (percentage of time the aircraft can perform one of its tasked missions) declined from 67 percent to 44 percent.
- The full mission capable rate (percentage of time the aircraft can perform all of its missions) declined from 38 percent to 25 percent.
In response, the F-35 Joint Program Office (JPO) updated its sustainment strategy, which it refers to as the Global Support Solution (GSS) Reset. The GSS Reset requires an estimated $13.7 billion more than previously planned through fiscal year 2031 and seeks to address challenges GAO previously identified, including a lack of spare parts and heavy reliance on contractors.
GAO found that multiple risks threaten JPO’s ability to achieve GSS Reset goals. For example, JPO will be reliant on the private sector to deliver more than $7 billion in additional parts and other material. But capacity constraints persist for key parts. Estimated costs for the F-35 also continue to increase. As a result, the U.S. military services will annually face a more than $1 billion gap between the projected costs to sustain their F-35s and their affordability goals by the mid-2030s. GSS Reset is a positive step toward addressing sustainment challenges, but risk mitigation plans would better position JPO to attain GSS Reset goals.
Further, JPO’s use of contract incentives did not achieve F-35 readiness goals, due in part to JPO paying incentive fees for performance that did not align with service requirements (see figure). Until JPO ensures the future use of incentives better achieves desired performance, it risks rewarding contractor performance that does not help meet program goals.
Minimum Full Mission Capable Rate (FMC) Requirements for Contractors to Receive a Portion of Incentive Fees Compared with Service Requirements, 2020–2023
Why GAO Did This Study
The F-35 aircraft is the Department of Defense’s (DOD) most costly weapon system, with lifetime sustainment costs for the United States alone estimated at $1.6 trillion, as of 2024. DOD operates and sustains over 800 U.S. F-35s and plans to buy about 1,700 more aircraft by the mid-2040s. DOD uses the F-35 to perform a wide range of missions. It is vital to the success of U.S. combat operations and homeland defense, according to DOD.
The National Defense Authorization Act for Fiscal Year 2022, as amended, includes a provision for GAO to conduct an annual review of F-35 sustainment efforts. This report assesses the extent to which JPO has evaluated the performance of its sustainment strategy and managed sustainment responsibilities with contractors to achieve goals, among other objectives.
GAO analyzed performance metrics, cost information, and sustainment contract incentive fee data for, among other things, full mission capable-related goals from 2020 through 2023, the last contract in which that metric was incentivized. GAO also reviewed relevant program documentation and interviewed DOD officials and contractor representatives.
Recommendations
GAO is making three recommendations, including for DOD to develop risk mitigation plans associated with GSS Reset and ensure that future incentive approaches better achieve the desired performance for sustainment contracts. DOD did not provide formal comments on this report but noted in draft comments that it concurred with the recommendations.
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of Defense | The Secretary of Defense should ensure that the F-35 Program Executive Officer proactively develops risk mitigation plans—including, but not limited to, for risks such as access to technical data, industry capacity, affordability, and alignment with service goals—associated with sustainment improvement initiatives such as the GSS Reset. (Recommendation 1) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
|
| Department of Defense | The Secretary of Defense, through the Under Secretary of Defense for Acquisition and Sustainment, in consultation with the F-35 Program Executive Officer, should ensure future incentive approaches better achieve the desired performance for sustainment contracts. Such approaches could include adopting penalties for poor performance, reevaluating incentive threshold levels to improve performance to meet service requirements, or omitting performance incentives. (Recommendation 2) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
|
| Department of Defense | The Secretary of Defense should ensure that the Under Secretary of Defense for Acquisition and Sustainment, in consultation with the F-35 Program Executive Officer, develops and implements a system with quality control safeguards in place to obtain, generate, and store relevant, quality incentive fee metric and payment information, and ensure that procedures for documenting changes to the contract are followed. (Recommendation 3) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
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