The F-35’s program chief conceded to senators Tuesday that the fighter has outgrown the system built to support it, weeks after a GAO report put readiness at the lowest level on record.
Marine Corps Lt. Gen. Gregory Masiello, who took over the F-35 Joint Program Office last July, testified before an open session of the Airland Subcommittee as the program defends a fiscal 2027 request that bundles more than $13 billion for the jet in fiscal 2027 alone. The request includes a buy of 85 U.S. aircraft and full funding for the Block 4 modernization effort and the engine core upgrade.
This hearing marks the first time the F-35 program’s leader has appeared before the subcommittee since 2016. Since then, the fleet has grown from 170 aircraft to more than 1,300.
In his written testimony, Masiello pointed to a sustainment system that was originally built to support 700 to 800 aircraft, well short of the fleet now flying.
“If I have over 1,300 operational aircraft out there, I believe we have set and enabled a sustainment system for about 7 to 800,” he said. “So there is our challenge in readiness.”
The hearing comes on the heels of a Government Accountability Office report this month that found just one in four F-35s were fully mission capable (FMC), meaning able to fly all assigned missions. Overall mission capable rates of jets able to fly at least one mission fell from 67% in fiscal 2021 to 44%.
Masiello put the program’s mission capable rate at 56%, above GAO’s 44%, a gap he ascribed to methodology. He stopped short of contesting the GAO’s FMC figure, but emphasized that “context matters,” arguing the discrepancy results from how his program defines mission capable.
Partially dragging down the FMC rate is the acceptance of incomplete jets. Pressed by ranking member Sen. Mark Kelly, D-Ariz., Masiello confirmed the Marine Corps has accepted six F-35Bs with no radar installed, opting instead to wait for a newer APG-85 radar.
When Kelly asked whether an F-35 with no radar could be considered FMC, Masiello conceded, “I don’t think I would count them as fully mission capable,” adding that he would discuss the radar’s capability in more detail in the closed session that followed.
Masiello blamed years of underbuying spare parts as the fleet grew, not a broken system. In response, the program has launched what it calls the Global Support Solution Reset, a roughly $13.7 billion effort through 2031 that targets five problem areas including spares, depot capacity and maintenance plans.
“It’s not a systemic issue with the system having the ability,” he said. “It’s the fact that we didn’t put enough parts and pieces on the shelf, and we’ve increased the demand exponentially with the number of aircraft fielded, and we didn’t do the same thing with the spare parts and the system.”
Asked what is most responsible for keeping jets from FMC status, Masiello pointed to software issues and the jet’s canopies, whose limited lifespan he called a particular problem on a low-observable jet.
The modernization track is running behind as well. The full Block 4 suite, once due in 2026, is now years off. Masiello said the program has fielded 22 of 55 planned Block 4 capabilities, the suite of new sensors, electronic warfare and weapons meant to keep the jet ahead of modern air defenses. The program fielded seven of those in last year’s software upgrade, with another six due this summer.
Contributing to modernization delays are the jet’s power and cooling capabilities. The engine core upgrade, slated for fielding in 2031, is meant to power and cool the full Block 4 suite, whose new radar and sensors draw more power and generate more heat than the current jet can handle.
On program accountability, Masiello said in his written statement that the program would revise contracts to carry “meaningful incentives and penalties,” a change GAO has urged for years after finding the program paid Lockheed Martin millions in fees even as readiness slid.
But that isn’t GAO’s only recommendation. GAO has made 46 sustainment recommendations since 2014, including three in this month’s report. As of March, the Pentagon had implemented just 14, leaving most still open a decade later.
Asked by the committee’s newest member, Sen. Ashley Moody, R-Fla., how many of the GAO’s recommendations the program had closed, Masiello wouldn’t commit to a specific number, preferring to note that they were “probably all to some degree in process.”
Despite all the criticism, the jet’s unique capabilities drew high praise from across the aisle. Kelly, a Democrat and former Navy combat pilot, called himself and the committee strong supporters of the F-35 program.
Kelly recalled flying an F-16 against an F-35, noting that he “could not see it on radar even when I’m looking right at it.” But he tied that support to accountability, telling Masiello the program needs to show it can improve readiness and control costs.
Masiello made the same case from the program side, citing the jet’s prominent role in recent operations, including Epic Fury, the U.S. air campaign against Iran. He said operators had told him it was “the only aircraft that can hit some of the targets” those missions required and could “act as a quarterback of that joint force.”
The program’s global reach adds to the sustainment burden. Allied nations own and operate most of the F-35s based in Europe and the Pacific, and they keep buying more.
Masiello said Poland signaled plans to double its 32-jet order during his visit this month, though he had not yet seen a contract. That growing fleet draws on the same global spares pool and sustainment system now straining to keep U.S. jets ready, even as it spreads the program’s cost and industrial base across allied countries.
Masiello warned that funding only part of the fiscal 2027 request would slow the production line and cut deliveries. For now, the readiness fight, modernization and the sustainment reset all hinge on a budget Congress has yet to pass.
Michael Scanlon is a defense journalist covering air and space warfare. A former U.S. Air Force A-10 crew chief, he has supported land and sea programs for the U.S. Army, Navy, Marine Corps and Coast Guard.
