F-35 Fleet: Only 25% Operational Due to Software and Hardware Failures

The F-35 program, the most expensive in military history with an estimated cost of $1.6 trillion, has taken another hit. According to a report by the Government Accountability Office (GAO) reported by TechRadar, the fleet of over 800 aircraft barely achieves a 25% fully mission capable rate. This means that only one in four fighters is ready to perform all its missions at any given time. This figure, far from being an isolated anomaly, reflects a persistent trend since 2019, when the rate fluctuated between 20% and 30%, well below the Pentagon's target of 80%. The program, which has accumulated cost overruns of more than $180 billion according to the GAO, faces a reliability crisis that compromises the national security of the United States and its allies.

What Happened?

The GAO report, published in May 2025, details that the problems are systemic and encompass both software and hardware. In the software domain, recurring bugs in the mission system—which integrates sensors, communications, and weapons—have caused 40% of test missions to not be completed successfully. According to the report, each new software update introduces an average of 50 new failures, forcing maintenance teams to constantly apply patches. On the hardware side, chronic failures are noted in the Pratt & Whitney F135 engine, which requires repairs every 1,200 flight hours instead of the planned 4,000. Problems are also reported in the fuel system, with leaks affecting 15% of the fleet, and in the aircraft structure, where cracks appear in the fuselage after 2,000 flight hours. Additionally, the spare parts supply chain is insufficient: the average wait time for critical parts is 45 days, prolonging downtime. The GAO notes that 30% of inoperable aircraft are down due to a lack of spare parts.

Why Is This Important?

The F-35 is the backbone of U.S. and allied combat aviation, with over 800 units delivered to 14 countries. With an acquisition and maintenance cost that exceeds the GDP of many countries—the operating cost per flight hour alone is $44,000, three times that of the F-16—its low availability compromises deterrence and rapid response capabilities. In a tense geopolitical context, with the war in Ukraine and tensions in the Indo-Pacific, the lack of combat-ready aircraft reduces NATO's ability to project power. For example, in 2024, the U.S. Air Force could only deploy 40% of its F-35s on a deterrence mission in Eastern Europe, according to leaked Pentagon documents. Moreover, the program has been criticized for chronic cost overruns and delays: development began in 2001 and initial operational capability was not declared until 2016, five years behind schedule. This report comes at a time when NATO seeks to strengthen its defensive posture against threats such as Russia and China, which have modernized their air forces with aircraft like the Su-57 and J-20.

Short- and Long-Term Consequences

In the short term, squadrons will have to prioritize missions and cannibalize parts from some aircraft to keep others operational. The GAO estimates that 20% of available aircraft are operational thanks to this practice, which in turn reduces component lifespan. Additionally, the Pentagon has had to reduce pilot flight hours from 200 to 150 per year, affecting training. In the long term, the Pentagon may be forced to cut orders or accelerate modernization programs, such as the F-35 Block 4, which promises to fix many of these failures through new software and hardware updates. However, the GAO warns that partial solutions are not enough; a thorough review of the design and maintenance model is needed. The report suggests that the Pentagon should consider a redesign of the engine and fuel system, as well as a review of the maintenance contract with Lockheed Martin, which is currently responsible for repairs. Compared to previous programs, such as the F-22 Raptor, which also suffered reliability issues but was canceled before reaching full production, the F-35 risks becoming a budgetary black hole. The total cost of the program could exceed $2 trillion if no action is taken, according to Congressional Budget Office estimates.

What Should Readers Know?

• It's not a new problem: Since 2019, the fully mission capable rate has fluctuated between 20% and 30%, well below the 80% target. In 2023, the rate was 27%, according to GAO data.
• Software is the Achilles' heel: The mission system requires constant updates, but each new version introduces new bugs. The GAO reports that the software has over 1,000 known unresolved failures.
• Hidden costs: Maintenance per flight hour is three times higher than that of the F-16, its predecessor. Additionally, the cost of unscheduled repairs has increased by 40% since 2020.
• Impact on allies: Countries like the United Kingdom, Italy, and Japan also operate the F-35 and suffer the same problems. The British RAF reported in 2024 that only 35% of its F-35s were operational at any given time, according to a parliamentary report.

"The F-35 is an extraordinary aircraft when it works, but the problem is it doesn't work as often as needed" — defense analyst quoted in the GAO report.

In conclusion, the GAO report is a wake-up call about the sustainability of the F-35 program. Without a course correction, the most expensive aircraft in history risks becoming a strategic burden, unable to fulfill its primary mission: ensuring air superiority for the U.S. and its allies. The lingering question is whether the Pentagon and Lockheed Martin are willing to make the drastic changes needed or if the program will continue its drift, consuming resources that could be allocated to other defense priorities.