The US has more than 800 F-35 fighters in service. Only one in four is ready to do everything he should

We have talked many times about F-35 as one of the great symbols of American air power, but its most pressing problem is not in the capabilities that have made it a centerpiece of US military aviation, nor even in the number of units planned for the coming decades. It’s on land. The latest GAO report once again puts numbers on the tension: the US has many F-35s, but the fleet spends much less time fully prepared than it should.

Deterioration. According to the GAOthe rate mission capable It measures the percentage of time in which an aircraft can fly and perform at least one of its assigned missions. The rate full mission capableon the other hand, measures when you can fulfill all of them. In fiscal year 2025, the US F-35 fleet recorded 44% in the first category and just 25% in the second. Simply put: America’s F-35s can do something a limited portion of the time, but are only fully ready a quarter of the time.

Background. The report shows that the problem has been accumulating for several years. Between fiscal year 2021 and fiscal year 2025, the rate mission capable of the fleet fell from 67% to 44%, while the rate full mission capable fell from 38% to 25%. The difference matters because we are not facing a minor maintenance oscillation, but rather a sustained loss of availability. What we have seen is a fleet that remains central to the United States, but that spends less and less time in a position to fulfill its missions.

New planes, old problems. One of the most striking parts of the document is that the 2025 drop is not explained only by aging devices or accumulated wear. Air Force officials attributed part of the decline to the acceptance of new aircraft that could not fulfill missions due to software delays. Added to this were the shortage of parts and inspection and repair work due to corrosion. The report also points to maintenance not optimized to reduce workload or time on the ground, and to high technical complexity due to the continuous development of the program.

Global Support Solution Reset. The F-35 Joint Program Office launched this update to its sustainment strategy in June 2025, with an ambitious goal for 2030: to bring the rate mission capable at 80% and the full mission capable 65% in the fleet as a whole. On paper, it is the attempt to correct years of accumulated problems in maintenance, parts and industrial support.

More money, not necessarily more margin. The solution is not only to reorganize processes or order more parts from the industry. It also requires a considerable budget injection. The document estimates that an additional $13.7 billion will be needed through fiscal year 2031, although not all of that money officially belongs to the GSS Reset. The Joint Program Office itself places that part at about 2.2 billion. The other 11.5 billion covers a wider gap: what the military branches had planned to spend versus what sustaining the fleet actually demands.

The most expensive plane also becomes more expensive on the ground: The problem does not end with availability or missing parts. Since 2021, according to the report, F-35 sustainment costs have continued to rise while the program has not met its performance goals and its performance has continued on a downward trend. The scale helps understand why it matters: the F-35 is the Department of Defense’s most expensive weapons system, with sustainment costs for the United States estimated at $1.6 trillion over its lifetime, according to 2024 figures. By the mid-2030s, military branches would face an annual gap of more than $1 billion between what it will cost to sustain their F-35s and what they consider affordable.

The exit. Auditors propose risk mitigation plans for initiatives such as the GSS Reset, a review of contractual incentives and a reliable system to record what is paid, why it is paid and with what results. The Department of Defense said it agreed with the recommendations, according to the report, but the challenge remains intact. The F-35 will remain a centerpiece of American military aviation for decades. The question is whether the US will achieve that this centrality is measured less by the number of aircraft purchased and more by how many are ready when needed.

Images | Aawyer Andrews

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