Key Points and Summary – The F-35 Lightning II is often praised as a stealthy, sensor-fused “flying computer,” but its track record reveals five serious weaknesses.
-The program’s lifetime cost has ballooned toward $2 trillion, with individual jets and Block 4 upgrades straining budgets.
U.S. Air Force Maj. Kristen “Beo” Wolfe, F-35A Lightning II Demonstration Team Commander with the 388th Fighter Wing, flies over the crowd during the Warriors Over the Wasatch Air and Space Show on June 25, 2022 at Hill Air Force Base, Utah. (U.S. Air Force photo by Senior Airman Erica Webster)
-Each flight hour is extremely expensive, driven by fuel burn and complex maintenance.
-The fleet still suffers from major Category One deficiencies, including handling and structural issues, and has endured repeated groundings tied to the finicky F135 engine.
-A string of accidents rounds out the concerns. Despite strong combat showings, the F-35 remains both indispensable and deeply problematic.
The Five Weaknesses of the F-35
We are accustomed to hearing about many of the F-35 Lightning II’s positive aspects. The stealthiness is paramount. It has admirable speed and agility.
The airplane will someday regularly fly Loyal Wingman drones.
It is a sophisticated “flying computer” with sensor fusion that can be easily updated as technology advances.
And the Israeli air force has souped up its own version of the F-35 to dominate the skies in the Middle East. It has also been a hit on the export market.
But the F-35 has its downsides.
U.S. Air Force Maj. Melanie “Mach” Kluesner, pilot of the F-35A Demonstration Team, performs aerial maneuvers during the Southernmost Airshow Spectacular at Naval Air Station Key West, Florida, on March 30, 2025. The team’s mission is to inspire, engage, and recruit the next generation of Airmen by showcasing the capabilities of the Air Force’s premier fifth-generation fighter. (U.S. Air Force photo by Senior Airman Nicholas Rupiper)
The airplane is highly expensive, whether you are analyzing the entire history of the program or the price of an individual fighter.
It is also costly to keep in the air.
There have been structural damages due to its maneuverability in flight.
Many F-35s have been grounded over the years, and the aircraft has been involved in several accidents.
This Airplane Has Been Dreadfully Expensive
First, let’s examine the costs. The U.S. Government Accountability Office has concluded that the program’s entire lifecycle, including future expenses over the next few decades, will cost a whopping $2 trillion.
That is an eye-watering sum.
In 2024, the Department of Defense announced a $16.5 billion Block 4 modernization program for the F-35 that the Air Force, Marine Corps, and Navy use.
This update focused on the engines and the thermal management system that made the radars overheat.
There are about 630 F-35s across the military. In 2018, it was estimated that the program’s total cost would be $1.1 trillion.
This increased by 44 percent five years later.
U.S. Air Force Maj. Melanie “Mach” Kluesner, pilot of the F-35A Demonstration Team, performs aerial maneuvers at the Sun ‘n Fun Airshow in Lakeland, Florida, April 4, 2025. The demonstration team showcases the skill and precision U.S. Air Force pilots and aircraft are capable of. (U.S. Air Force photo by Senior Airman Nicholas Rupiper)
Each F-35 can cost between $82 million and $102 million, depending on the variant.
The GAO said that “over the course of the last couple of years, the Air Force and Navy have also reduced their projected annual flying times by 19 percent and 45 percent respectively.”
Price Per Flight Hour Is Prohibitive
Second, the F-35 is expensive to keep in the air.
Each flight hour sets the DOD back $42,000. And that figure was from FY2020.
Inflation and supply chain issues have driven up costs since then.
The F-35 is a fuel hog, and each flight requires at least 9,700 pounds of JP-8 fuel.
Plus, the military must train and pay maintainers. The AN/APG-81 AESA radar and the AN/ASQ-239 electronic warfare suite require skillful and experienced technicians who must be compensated accordingly.
Their work also takes time and this can keep the F-35 on the ground for extended periods.
Technical Issues Have Mounted
Third, the F-35 has Category One deficiencies, comprising 13 major technical problems. There are also five minor issues known as Category Two deficiencies.
“A Category One deficiency is defined as a shortfall that could cause death, severe injury or illness; could cause loss or damage to the aircraft or its equipment; critically restricts the operator’s ability to be ready for combat; prevents the jet from performing well enough to accomplish primary or secondary missions; results in a work stoppage at the production line; or blocks mission-critical test points, according to Defense News.
A U.S. Marine Corps F-35C Lightning II assigned to Marine Fighter Attack Squadron 251 (VMFA-251), Marine Corps Air Station Cherry Point, North Carolina, takes off for a mission in support of Red Flag-Nellis Marine Fighter Attack Squadron 251 (VMFA-251), 2nd Marine Aircraft Wing, Marine Corps Air Station Cherry Point, North Carolina 25-3 from Nellis Air Force Base, Nevada, July 22, 2025. Red Flag, strengthens join-force readiness through integration in realistic combat scenarios, enhancing interoperability and rapid-response capabilities. (U.S. Air Force photo by William R. Lewis)
One example of these deficiencies would be F-35B and F-35C variants used by the Marine Corps and Navy, which would become hard to fly when going beyond a 20-degree angle of attack, “which would be seen in the extreme maneuvers a pilot might use in a dogfight or while avoiding a missile.”
There are also pitch and yaw issues. Stealth coatings and complex sensors must also be maintained. Moreover, there are cracks in the airframe from constant flights.
This Warbird Must Stay On the Ground Periodically
Fourth, the airplane has been grounded several times due to systemic failures.
The Pratt & Whitney F135 engine is finicky and often encounters difficulties, rendering it combat-ineffective.
For example, there has been “a faulty tube used to transfer high-pressure fuel” to the engine, according to Forbes.
Forbes also said that there has been a “loss of control and/or thrust during its pre-acceptance functional test flights” after the grounding periods are over.
Also, in 2022, 36 F-35As were grounded due to inoperable engines.
This is not limited to the United States. The Belgian Air Force claimed this year that one of its new F-35s had to be grounded for “unscheduled” maintenance.
This was an embarrassment to Lockheed Martin because the F-35 was right off the production line.
The List of Accidental Crashes Is Long
Fifth, there have been numerous F-35 accidents over the years.
This July, an F-35 “fell out of the sky” and crashed near Naval Air Station Lemoore in Central California. There have been a dozen such crashes since 2018.
In January of 2025, an F-35 went down in Alaska. The pilot escaped unharmed, but the latest disappointments have been embarrassing for the program.
In April 2019, an F-35 pilot flown by the Japanese air force fell into the Pacific Ocean in a tragedy that killed the pilot.
Usually, pilots can eject safely.
F-35: What To Think
Despite its downsides, the F-35 can still be considered a successful fighter.
Air Force F-35s played a successful role in Operation Midnight Hammer attacks against Iranian nuclear infrastructure.
The Israeli F-35I may be one of the world’s most advanced stealth jets.
Yes, the F-35 is one of the most expensive warbirds.
Two trillion dollars is nothing to ignore.
The airplane is costly to keep flying, and it is often grounded due to engine problems and other structural deficits.
There have been accidents that have taken the life of one pilot. But the DOD and 19 partner nations are stuck with the F-35 and will continue to fly it for decades. The maintainers will be busy keeping it operating.
We’ll see what kind of performance it can display in future combat, but the Israelis and Americans have flown the warbird in wartime conditions.
So far, the Israelis have not lost a single F-35I to enemy fire, and neither have the Americans. That’s the kind of record that the F-35s must display regularly before the program can be considered a full-on success.
About the Author: Brent M. Eastwood
Author of now over 3,000 articles on defense issues, Brent M. Eastwood, PhD is the author of Don’t Turn Your Back On the World: a Conservative Foreign Policy and Humans, Machines, and Data: Future Trends in Warfare plus two other books. Brent was the founder and CEO of a tech firm that predicted world events using artificial intelligence. He served as a legislative fellow for US Senator Tim Scott and advised the senator on defense and foreign policy issues. He has taught at American University, George Washington University, and George Mason University. Brent is a former US Army Infantry officer. He can be followed on X @BMEastwood.
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