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75 Upgrades for F-35 Block 4 That Transform Fifth-Generation Air Power.
Since its inception, the F-35 Lightning II has been a cornerstone of military aviation technology. With the introduction of the Block 4 upgrade, the aircraft is undergoing a significant transformation through substantial hardware and software enhancements, fundamentally altering its operational capabilities. Rather than merely addressing gaps or adding minor features, this update represents a comprehensive evolution of the platform.
The Block 4 upgrade introduces an open mission systems architecture, a next-generation integrated processor with significantly increased computing power, an enhanced panoramic cockpit display, and expanded memory (Picture source: Lockheed Martin)
The Block 4 modernization program began in 2018 with the goal of integrating 75 new features. These include advanced maintenance diagnostics, enhanced communication capabilities, new weapon integration, and software upgrades aimed at addressing existing limitations. However, the program has faced delays due to challenges in developing and integrating new technologies. Issues such as supply chain disruptions and extended testing schedules have affected the TR-3 configuration, a critical component of Block 4. Despite these hurdles, deliveries of F-35 aircraft equipped with TR-3 resumed in July 2024.
The Technology Refresh 3 (TR-3) serves as the backbone of the Block 4 upgrade. It introduces an open mission systems architecture, a next-generation integrated processor with significantly increased computing power, an enhanced panoramic cockpit display, and expanded memory. These upgrades deliver computing capabilities 25 times greater than earlier configurations, ensuring the aircraft remains capable of addressing evolving threats.
Key hardware improvements include the integration of the AN/APG-85 radar, which replaces the AN/APG-81. This active electronically scanned array (AESA) radar enhances target detection and tracking, improving pilot situational awareness. Additionally, the propulsion system is being upgraded through Pratt & Whitney's F135 Engine Core Upgrade (ECU), which aims to enhance durability, performance, and lifecycle cost efficiency.
The Block 4 program introduces over 75 major updates across all three F-35 variants. These include increased payload capacity, advanced electronic warfare (EW) capabilities, and enhanced target recognition. Collectively, these upgrades aim to improve lethality, survivability, and overall mission effectiveness.
The F-35's payload capacity has been increased to 18,000 pounds (8,200 kg), expanding its operational versatility. Newly integrated weapons include the AIM-260 Joint Advanced Tactical Missile (JATM), the AGM-158C Long-Range Anti-Ship Missile (LRASM), and other systems under development, such as SPEAR 3. These additions further enhance the aircraft’s capability for air superiority, interdiction, and deep strike missions.
Upgrades in reconnaissance systems include improvements to the radar (AN/APG-85) and electro-optical systems such as the AN/AAQ-37 and AN/AAQ-40, providing greater targeting accuracy while minimizing collateral damage (Picture source: US DOD)
In the realm of electronic warfare, the Block 4 upgrade enhances the F-35’s ability to detect and neutralize adversary systems through advanced software and waveforms. These non-kinetic capabilities complement existing systems, such as the Barracuda electronic countermeasures suite.
Upgrades in reconnaissance systems include improvements to the radar (AN/APG-85) and electro-optical systems such as the AN/AAQ-37 and AN/AAQ-40, providing greater targeting accuracy while minimizing collateral damage. This advancement improves overall mission efficiency.
The open architecture introduced in Block 4 provides unprecedented flexibility for future system integration. This ensures technological longevity, reduces dependency on specific suppliers, and simplifies future upgrades and compatibility enhancements.
Despite the delays caused by supply chain issues and extended testing, a limited TR-3 configuration has enabled F-35 deliveries to resume. Initial testing of the upgraded ECU is expected by 2026, with deliveries projected to begin in 2029.
The Block 4 upgrade also enhances the capabilities of F-35 aircraft operated by international partners. These improvements support deterrence efforts in strategically important regions such as Europe and the Indo-Pacific. By enhancing the capabilities of allied nations, the F-35 program contributes to global security initiatives.
Several countries have chosen to include the F-35 in their air forces, including the United States, the United Kingdom, Italy, the Netherlands, Australia, Denmark, Norway, South Korea, Japan, Israel, Belgium, Poland, Finland, Switzerland, Canada, the Czech Republic, and Greece. Some have specifically opted for the Block 4 standard, incorporating its advanced features. For instance, Switzerland ordered 36 F-35A Block 4 aircraft in September 2022, with deliveries scheduled between 2027 and 2030. Similarly, the Czech Republic signed a contract in January 2024 for 24 F-35A Block 4 aircraft. These acquisitions demonstrate a commitment to adopting advanced versions of the F-35 to enhance national defense capabilities.