US Air Force to Replace Oldest F-35s Instead of Upgrading Them

A Pragmatic Pivot: Why the U.S. Air Force Is Replacing Its Oldest F-35s

The F-35 Lightning II stands as the centerpiece of modern air combat for the United States and its allies. As a fifth-generation, multirole fighter, its development and deployment represent one of the most ambitious and expensive defense programs in history. The U.S. Air Force’s long-term vision includes acquiring a massive fleet of 1,763 F-35A variants, making it the backbone of its tactical airpower for decades to come. This long-term plan, however, is now facing a significant strategic adjustment.

In a notable shift, the Air Forces has decided to phase out its earliest F-35A models rather than subject them to a complex and costly modernization process. This move, detailed in a congressionally mandated report, involves divesting the older, non-combat-capable jets instead of upgrading them to the advanced Block 4 standard. This decision is not a retreat from the F-35 program itself but rather a calculated course correction, driven by the immense technical and financial challenges associated with the Block 4 upgrade. It signals a pragmatic choice to prioritize the acquisition of new, factory-fresh aircraft over the difficult task of retrofitting the oldest airframes.

The Rationale: Cost-Effectiveness Over Complex Retrofits

The core of the Air Force’s decision lies in a simple, yet critical, calculation: it is more efficient to buy new F-35s than to upgrade the old ones. The Military-Aircraft targeted for replacement are from the early low-rate initial production (LRIP) phases. These jets were built before the design was finalized and lack the full combat capabilities of their more modern counterparts. Bringing them up to the latest Block 4 configuration would require extensive, invasive, and expensive modifications.

This strategy is also an attempt to move away from what has been termed “acquisition malpractice”, the practice of developing, testing, and producing a weapons system concurrently. This approach has historically led to costly retrofits as design flaws are discovered after aircraft have already been built. By focusing on procuring new F-35s built with the latest technology from the ground up, the Air Force aims to field a more reliable and capable fleet faster. The service is looking to significantly ramp up its procurement rate, with a goal of acquiring as many as 80 F-35As annually.

Lockheed Martin, the F-35’s Manufacturers, has indicated a potential production capacity of up to 100 F-35As per year by fiscal year 2030. This industrial capacity supports the Air Force’s strategy, making the replacement plan a viable path toward achieving its total fleet objective of 1,763 aircraft without sinking more resources into the most problematic early models.

The Troubled Block 4 Upgrade

The decision to replace the older jets is inextricably linked to the severe difficulties plaguing the Block 4 modernization program. Block 4 is a critical but massive undertaking, designed to equip the F-35 with the capabilities needed to counter advanced future threats. The upgrade includes over 75 major improvements, such as increased missile capacity, next-generation electronic warfare systems, and enhanced target recognition.

However, the program has fallen far behind schedule and ballooned in cost. A Government Accountability Office (GAO) report painted a stark picture, revealing that the Block 4 upgrade is five years behind schedule and a staggering $6 billion over budget. Full integration of all planned capabilities is not anticipated until 2031. These persistent delays and cost overruns have forced the F-35 program to consider reducing the overall scope of the modernization effort.

A key technical hurdle has been the development of Technology Refresh 3 (TR-3), the new hardware and software core intended to provide the necessary computing power for Block 4’s advanced features. TR-3 has faced its own significant developmental challenges, creating a bottleneck for the entire modernization pipeline. In 2024, these issues contributed to Delivery delays for all new F-35s, with an average delay of 238 days per aircraft.

The attempt to make the F-35 a jack-of-all-trades has been cited as a fundamental challenge, with one analyst noting it was a flaw to try and make the aircraft do too much. This complexity is now manifesting in the difficulties of the Block 4 upgrade.

Broader Implications for the Future Fighter Fleet

This strategic pivot on the F-35 is part of a larger evolution in the Air Force’s approach to its fighter fleet. The service is moving toward a mixed-fleet model, balancing the high-end capabilities of the F-35 with other, more affordable aircraft. This is evidenced by the increased procurement of the Boeing F-15EX Eagle II, a modernized fourth-generation fighter intended to complement the F-35 and handle missions that do not require stealth.

The high operating and maintenance costs of the F-35 have long been a point of concern. Former Air Force officials have described the jet as a “Ferrari” that shouldn’t be used for daily, low-end fights. By investing in a mix of aircraft, the Air Force can optimize its fleet for a wider range of missions and manage sustainment costs more effectively.

Furthermore, this decision allows the Air Force to focus resources on the future. The service is already looking ahead to its sixth-generation fighter, part of the Next-Generation Air Dominance (NGAD) program, and the integration of Collaborative Combat Aircraft (CCAs), or “drone wingmen.” Divesting the oldest F-35s frees up funding and logistical capacity that can be redirected toward these next-generation priorities, ensuring the U.S. maintains its edge in air superiority for decades to come.

Conclusion: A Pragmatic Path Forward

The U.S. Air Force’s decision to replace its earliest F-35A models is a clear-eyed response to the realities of a complex and troubled modernization program. Faced with the immense cost and technical risk of upgrading its oldest jets, the service has chosen a more pragmatic path: accelerate the acquisition of new, fully capable aircraft. This move aims to avoid repeating past mistakes and ensures that the warfighter receives the most advanced technology available without delay.

This strategic shift underscores a broader evolution in military procurement, prioritizing efficiency and future-readiness. By balancing the F-35 fleet with complementary aircraft like the F-15EX and investing in next-generation systems, the Air Force is building a more resilient and adaptable fighter force. The F-35 remains the cornerstone of that force, but this decision ensures the foundation is built with the strongest, most modern assets available.

FAQ

Question: Why is the Air Force getting rid of its older F-35s?
Answer: The Air Force has determined that it is more cost-effective and efficient to replace the oldest, non-combat-capable F-35As with new aircraft rather than undertaking the expensive and complex upgrades required to bring them to the modern Block 4 standard.

Question: What is the F-35 Block 4 upgrade?
Answer: Block 4 is a comprehensive modernization program for the F-35, encompassing over 75 major improvements in areas like electronic warfare, processing power, and weapons capacity. However, the program is currently five years behind schedule and $6 billion over budget.

Question: How many F-35s does the Air Force plan to own?
Answer: The U.S. Air Force’s official program of record is to acquire a total of 1,763 F-35A aircraft.

Sources

• Aviation Week