- DOT&E said the F-35 fielded no new combat capability in fiscal year 2025 after TR-2 and TR-3 software builds remained unstable or unsuitable for dedicated operational testing.
- The report said software delays, reduced planned capability in key releases, and test resource shortfalls continued to slow Block 4 progress across the U.S. military’s F-35 fleet.
The F-35 program fielded no new combat capability during fiscal year 2025 after software problems delayed operational testing across both Technology Refresh 2 and Technology Refresh 3 aircraft configurations, according to the Pentagon’s Director, Operational Test and Evaluation annual report.
DOT&E said the latest TR-3 software build, 40R02, was “unsuitable for dedicated OT,” while the latest TR-2 build, 30R08, was “predominantly unusable” during most of FY25 because of stability problems, capability shortfalls, and ongoing discovery of deficiencies.
The development matters because the F-35 program is the United States military’s core tactical fighter effort across the Air Force, Marine Corps, and Navy, and new software drops are the path for adding Block 4 combat functions to the fleet. When those software builds are not stable enough for operational testing, new capabilities cannot move from development into fielded service.
According to DOT&E, development teams spent FY25 working on two separate software lines tied to different hardware baselines. One line supported TR-2 aircraft, which make up most of the fielded fleet, while the other supported TR-3 aircraft, whose upgraded avionics are intended to enable future Block 4 mission systems capabilities. Despite TR-3 being described as a rehost of TR-2 software, the latest TR-3 build was still not ready for dedicated operational test use.
The problems were not limited to one software path. DOT&E said 30R08, the version intended to be the last software release fielded on TR-2 aircraft, remained largely unusable for most of the year. Dedicated operational testing with 30R08 did not begin until September 2025, when operational test squadrons took part in the large exercise GRAY FLAG 2025 using the latest version of that software. DOT&E’s summary was direct: “As such, no new combat capability was fielded in FY25.”
The broader performance section of the report shows this was not a one-off slip but part of a longer pattern. DOT&E wrote that the F-35 program “continues to show no improvement in meeting schedule and performance timelines for developing and testing software,” and said the process of fixing deficiencies and adding new capabilities had stagnated. It added that the 30-series software family had been in a fly-fix-fly development cycle for nearly four years.
DOT&E also described repeated schedule and content erosion inside the 30-series line. The report says both 30R06 and 30R08 took longer than planned and required more software iterations than expected to address discoveries and deficiencies. It further states that both 30R07 and 30R08 delivered, or were set to deliver, with less capability than originally planned. The result, according to DOT&E, was no meaningful 30-series capability improvement in the latest software versions, while the 40-series TR-3 software fell further behind and accumulated new deficiencies.
Those software delays are now affecting operational test capacity as well. DOT&E said the F-35 Joint Program Office planned needed modifications for operational test aircraft, but resource shortfalls prevented timely delivery. Current aircraft forecasts, the report says, show there will not be enough operational test aircraft available to carry out dedicated operational testing in representative formations. That matters because tactical aircraft are not judged only as individual jets; they must be tested in the kinds of formations and mission scenarios they would face in combat.
The report also raised concerns about the Joint Simulation Environment, which is meant to support evaluation of advanced threats and higher-end mission performance. DOT&E said the program has only one F-35 In-a-Box delivery contracted after the 40S03 software release next year and called that situation unacceptable. The Joint Program Office plans to add more FIAB systems later as the Block 4 configuration plan matures, but for now the testing infrastructure remains constrained.
The F-35 depends on software as much as airframe hardware. The aircraft’s combat value comes from how its sensors, mission systems, electronic warfare functions, weapons integration, and data fusion work together. Block 4 modernization is intended to deliver incremental improvements under what DOT&E described as an agile acquisition framework, but that framework only works if each software release is stable enough to test and field.
DOT&E’s FY25 report also underscores that TR-3 itself remains a gating factor for future capability growth. The TR-3 avionics upgrade includes upgraded mission computers, memory systems, and panoramic cockpit displays, and the report describes it as a key enabler for new Block 4 mission systems capabilities. But problems with TR-3 hardware and software had already delayed delivery of Lot 15 production aircraft, which were placed into storage until performance improved.
Separately, Breaking Defense reported that beginning this fall, some new F-35 aircraft delivered to the U.S. military could arrive without installed radars because of delays tied to the next-generation APG-85 system. According to that reporting, the APG-85 differs in size from the current APG-81 and requires structural changes to the aircraft, preventing the older radar from being fitted to airframes built for the newer system.
Breaking Defense reported that aircraft delivered in that configuration would remain airworthy but would not be combat-capable, allowing only limited training use.
The F-35 remains a tri-service, multinational strike fighter program meant to replace legacy aircraft across the United States Air Force, Marine Corps, and Navy. Its missions include attacks on fixed and mobile land targets, surface combatants at sea, and air threats, including advanced aircraft and cruise missiles, during day and night operations in heavily defended areas.
That mission set is why the pace of software fielding draws close attention: delayed code delivery means delayed combat functionality across one of the most important tactical aircraft fleets in U.S. service.