Championing Responsible National Security Policy

F-35: The Part-Time Fighter Jet

The F-35 fleet can only perform the full range of its combat roles 30% of the time. This unreliability renders the entire program ineffective.

(Illustration: Ren Velez / POGO; Photos: Getty Images)

The F-35 program officially began on October 26, 2001, when Lockheed Martin received the coveted development contract. That day was more than 22 years ago. The costs of the program through its anticipated lifespan have risen $1.7 trillion since then. What the American people have so far received for that enormous financial commitment is an aircraft program where less than a third of the jets are capable of performing their combat role according to multiple government sources: The Pentagon’s top testing office, the Director, Operational Test & Evaluation (DOT&E), recently released its office’s annual report, which showed that the F-35 program has a fleet-wide full mission capable rate of only 30%.

This year’s unclassified version of the report is rather thin. Many details about the F-35’s demonstrated performance in 2023 are presumably hidden in the classified version of the report submitted to Congress and the secretary of defense. The testing director did say that results from the testing process will be included in the F-35 program’s initial operational test and evaluation report, now expected to be released before the end of March 2024.

One single detail about the program’s abysmal availability rate in the unclassified version of the report says a lot about how poorly the F-35 performs. It doesn’t actually matter what kind of dazzling capabilities the F-35 may one day be able to perform: If the aircraft can’t be relied upon to perform when needed, then any potential capability is useless.


“Availability is determined by measuring the percentage of time individual aircraft are in an ‘available’ status, aggregated monthly over a reporting period.” That is how the testing director defined aircraft availability in this year’s report. Program officials set a 65% availability goal for the F-35 fleet. 

The data shows the program is not coming anywhere close to meeting that goal. 

For the 12-month period ending in September 2023, the F-35 fleet managed to achieve only a 51% average monthly availability rate: Only half of the 628 F-35s delivered to the Department of Defense were ready to perform at any given time during fiscal year 2023.

That is a pretty poor performance, but the story is even worse when the data is examined more closely. The 65% availability target is for aircraft that are categorized as mission capable. The services consider an aircraft as mission capable if it can perform at least one of the program’s assigned missions. Such a threshold may be appropriate for a program like the C-17 transport, which has essentially a single mission. For a multi-role program like the F-35, however, a different standard should be used. Because the F-35 is designed to perform many missions, from delivering nuclear weapons to supporting troops on the ground, program officials aren’t even using the right yardstick to measure the aircraft’s performance.

It doesn’t actually matter what kind of dazzling capabilities the F-35 may one day be able to perform: If the aircraft can’t be relied upon to perform when needed, then any potential capability is useless.

Fortunately, such a yardstick does exist. It is the full mission capable rate, or the percentage of aircraft available to perform all the assigned missions. The testing director said the full mission capable rate standard is “a better evaluation of combat readiness” for the F-35 program. When this higher standard is applied to the F-35 fleet, the magnitude of the program’s failure becomes clear: DOT&E reports the full mission capable rate for the F-35 fleet was 30% in 2023.

F-35 defenders will undoubtedly say the 30% fleet-wide figure doesn’t mean much because many of the aircraft counted are in a life-cycle period, such as undergoing major overhauls, during which they would not be expected to be pushed into combat service. There is some truth to that, but the testing director took that into account. The report provides the full mission capable rate for the “combat-coded” aircraft, or those assigned to active squadrons with an assigned combat mission. The portion of the F-35 fleet that is supposed to be ready to fight at a moment’s notice has a full mission capable rate of only 48%. 

That means that more than half of the F-35s that should be ready for combat aren’t.

F-35 Availability Degraders 

A number of issues contribute to the F-35 fleet’s poor reliability.

One issue that has been known for years is that the program does not have the capacity to efficiently repair aircraft when they break. F-35s break down far more frequently than the architects of the program anticipated. DOT&E reports that the fleet of Air Force F-35As experience critical failures, those that render an aircraft unsafe to fly, nearly twice as often as anticipated.

Major maintenance work on aircraft is done at maintenance depots scattered around the country. The depots are usually government-owned and contractor-operated. Personnel perform major overhauls, rebuilds, and modifications beyond what can be done by front-line maintenance crews. The Government Accountability Office released a report in September 2023 detailing how bad the situation is with the maintenance depots. It turns out that not only do F-35s break down more often than anticipated, but it takes far too long to repair them. The Pentagon established a 60-day goal for repair times at the depots. As of February 2023, it took an average of 141 days to cycle an F-35 through the depot process. That was actually a slight improvement from the situation identified by the Government Accountability Office in a 2017 report, when the average time was 172 days. The program had managed to winnow that down to 131 days in August 2020, but a lot of that progress has clearly evaporated.

The program’s inability to solve the depot capacity problem is particularly surprising because this has been a known issue for many years, and was even highlighted in another 2017 GAO report. The Pentagon is now 12 years behind schedule in fully standing up the maintenance depots. 

With a concerted effort, it could be possible to reverse course and increase depot capacity, but another fundamental problem with the F-35 program is far more intractable: The entire F-35 enterprise relies heavily on Lockheed Martin contractors to keep the program running. That is by design per the original contract. The Pentagon structured the program under the Total System Performance Responsibility concept, which meant the contractor would perform the majority of the sustainment work for the program. That ensured a reliable revenue stream for Lockheed Martin, but has hampered the overall effectiveness of the program. It takes contract maintainers more than twice as long as their uniformed counterparts to complete the maintenance work, according to the GAO. 

The entire F-35 enterprise relies heavily on Lockheed Martin contractors to keep the program running.

On a slightly positive note, one problem that has recently crippled a significant portion of the F-35 has apparently been solved for the time being. A shortage of parts for the F-35’s engine left dozens of aircraft on the ground over the past few years. According to DOT&E, a combination of additional depot resources and improved manufacturing has increased the number of available engines. Unfortunately, there are still plenty of other components in short supply. F-35s sit idle for lack of canopies, distributed aperture system sensors, nacelle vent fans, and at least seven other critical components

It has been known for years that the services are buying new F-35s much faster than the depot capacity could handle. Rather than slow down aircraft production to allow all the support networks to catch up to meet the increased demand, however, the Pentagon wants to push ahead and buy up to 780 new F-35s before the end of the decade.

Upgrades Lagging

A major theme weaved throughout DOT&E’s F-35 report is the program’s immaturity, despite the fact that development has been underway since the beginning of the century. Even though the program still hasn’t met the criteria for full rate production of the initial version of the jet, the Pentagon launched a “modernization” effort variously referred to as Block 4 or Continuous Capability Development and Delivery (C2D2) in 2017. While program officials called the effort a modernization plan, what they were really doing was pushing unfinished development work to a later phase after they ran out of money and time to complete basic design work. But even this phase of the program has floundered by blowing right past delivery schedules and seeing costs rise from $10.6 billion to $16.5 billion for the additional development work. 

The DOT&E report frequently mentions modifications that have yet to be completed or software updates that are still needed, as well as a behind-schedule migration to a new maintenance and logistics information network. 

These developmental delays have gotten so bad that the Pentagon has refused to accept new F-35s off the assembly line until the manufacturer completes work on the Technology Refresh 3, or TR-3 for short, a project that includes an upgraded processor, improved displays, and software updates to expand the number of weapons the aircraft can employ. TR-3 is a preliminary step to the program’s Block 4 “modernization” process that has been in the works for years.

DOT&E reports that continued TR-3 delays have also impacted the testing process. The Joint Test Team completed only 32 of 205 baseline developmental test flights in fiscal 2023 because the testing aircraft haven’t received the modifications necessary to conduct those tests. That will impact the later operational testing, which is designed to see how the new upgrades will perform in realistic settings. 

Another DOT&E finding is that the F-35 program is still struggling to replace its troubled maintenance and logistics network. The F-35 fleet currently relies on the ground-based Autonomic Logistics Information System, or ALIS, to download diagnostic data from the aircraft, create maintenance work orders, track spare parts through the supply chain, and then guide crews through the necessary repair work. The network is also used by pilots to plan missions. ALIS has been plagued with interface and connectivity issues for years. Operators often found the system so troublesome they had to resort to lengthy workarounds to manually enter data. The problems became so bad that program officials finally decided to scrap ALIS and replace it with a new cloud-based network called Operational Data Integrated Network (ODIN).

The transition from ALIS to ODIN, like most aspects of the F-35 saga, has faced major schedule delays. When officials announced the switch in early 2020, they said the new network would be fully operational by the end of 2022. DOT&E reports that the necessary flightline hardware has been delayed and won’t be fully in place until sometime in 2025.

Testing Report Still Short on Details

The F-35 officially entered the operational testing phase in late 2018 and was initially expected to complete the process within a year. That initial optimism, too, proved to be unwarranted. More than five years later, officials now say they have completed all the testing events necessary to write the report necessary to satisfy the legal requirements for a full-rate production decision.

According to DOT&E, that report is expected before the end of March 2024. It is anticipated that the F-35 initial operational test and evaluation report will be classified. Based on the scanty information available today, it will be difficult for the people funding the program — the American people — to judge for themselves the accuracy of the rosy pronouncements emanating from the Pentagon.

The public has a right to be skeptical about the F-35. The program has been in development for more than 22 years. That is an incredibly long time to field an aircraft fleet. Entire programs have gone from the proverbial napkin sketches to the boneyard in less time. The B-36 program was first conceptualized in 1941, saw a full lifetime of usefulness, and was then retired 18 years later in February 1959.

It will be difficult for the people funding the program — the American people — to judge for themselves the accuracy of the rosy pronouncements emanating from the Pentagon.

The F-35 program completed the final tests for the initial operational test and evaluation phase in September 2023. The anticipated report for that process is the final legal hurdle the program has to overcome before the Pentagon’s acquisition chief can sign off on full rate production. It is difficult to imagine a scenario in which that doesn’t happen at this point. Far too much time and money has already been spent on the F-35. 

But even if DOT&E signs off after nearly 23 years on the initial design of the F-35, there are plenty of new unforeseen problems requiring retrofits before these weapons will be “ready” for combat. As mentioned previously, the military is already not accepting fresh F-35s that have not been updated with the necessary equipment. There will likely be several budgetary fights this year over either designing entirely new engines and cooling systems or solving the fleet-wide power, cooling, and propulsion problems plaguing those systems. The bottom line is that this aircraft will be far from combat ready even if the Pentagon’s acquisition office authorizes full rate production.

No matter what happens, this story is far from over. The F-35 program still has years of further development work to go before the jet approaches the lofty goals set for it a generation ago. As the Pentagon and Congress begin to consider plans for the next generation of U.S. weapons systems and combat aircraft, we must learn from these serious mistakes. We cannot approach weapons development with the same sort of weak oversight, negligent accountability, and poor evaluation standards that resulted in the most expensive and least ready modern combat aircraft in our history.

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