F-35 program faces delays and software challenges

The F-35 Joint Strike Fighter (JSF) program has officially entered full-rate production following an Acquisition Decision Memorandum (ADM) signed in March 2024. However, new reports from the U.S. Department of Defense’s Director, Operational Test & Evaluation (DOT&E) highlight ongoing challenges with software integration, production quality, and mission readiness.

The latest F-35 combined Initial Operational Test and Evaluation (IOT&E) and Live Fire Test and Evaluation (LFT&E) report, released in February 2025, assesses the overall mission capability of the F-35 in its Block 3F configuration. It also includes an annex detailing the current status of Block 4 operational testing and the Technology Refresh 3 (TR-3) upgrade—both of which are facing delays and software instability.

The F-35 Joint Program Office (JPO) had initially planned for Lot 15 aircraft—the first to feature TR-3 mission systems architecture—to be delivered in July 2023. However, software functionality issues forced the U.S. military to pause aircraft acceptance for nearly a year.

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By July 2024, the U.S. Air Force began accepting TR-3 aircraft, but with truncated software versions that disabled key combat capabilities already fielded in previous TR-2 aircraft. The F-35 development team is still struggling to deliver stable and fully functional software, causing operational test teams to halt evaluations due to performance shortfalls and deficiencies.

The DOT&E report warns that full operational testing for TR-3-equipped aircraft will not take place until mid-to-late FY2026, nearly two years after the configuration was first introduced. This means that fielded TR-3 aircraft may remain combat-incomplete until further software refinements are made.

The United Operational Test Team (UOTT)—which oversees F-35 testing—issued a “stop test” order in February 2024, citing:

  • Unstable software performance
  • Critical deficiencies affecting capability
  • Persistent mission system failures

The DOT&E report also raised concerns over cybersecurity vulnerabilities. The F-35’s logistics and sustainment system, previously Autonomic Logistics Information System (ALIS) and now transitioning to Operational Data Integrated Network (ODIN), has faced developmental challenges and cyber risks.

The ODIN software, intended to improve maintenance efficiency and aircraft availability, remains partially implemented. The transition plan, initially described as a “lift and shift” of ALIS into ODIN, has now evolved into a multi-year phased rollout with incremental updates every six months.

While the JPO has reported improvements in production quality, with scrap, rework, and repair times reduced by 47% since 2016, quality escapes—defects that should have been caught during factory inspections—are still appearing in fielded aircraft.

A U.S. Marine Corps fighter squadron in California recently discovered a series of production defects in newly delivered F-35C aircraft, raising concerns over manufacturing consistency at Lockheed Martin’s Fort Worth facility.

Despite these challenges, the F-35 remains the backbone of U.S. and allied airpower. The Block 4 modernization program, which includes new sensors, weapons integration, and improved computing power, is expected to enhance the fighter’s capabilities over time.

However, software instability, cyber vulnerabilities, and production setbacks could delay the full operational deployment of these upgrades.

The DOT&E report recommends prioritizing:

  • Stabilization of TR-3 software before further aircraft deliveries
  • Cybersecurity testing of ODIN before full implementation
  • Increased scrutiny of F-35 manufacturing and quality control

As the U.S. military and its allies continue to rely on the F-35, the success of the TR-3 and Block 4 upgrades will determine whether the fighter can meet its full combat potential.

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Executive Editor

About author:

Dylan Malyasov
Dylan Malyasov
Dylan Malyasov is the editor-in-chief of Defence Blog. He is a journalist, an accredited defense advisor, and a consultant. His background as a defense advisor and consultant adds a unique perspective to his journalistic endeavors, ensuring that his reporting is well-informed and authoritative. read more

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