Focus | Lockheed Martin prepares first Block 4 software updates to increase the F-35’s combat capabilities
{loadposition bannertop}
{loadposition sidebarpub}
As reported by Air & Space Forces on March 10, 2025, Lockheed Martin is set to begin releasing the first software updates for the F-35 Block 4 upgrade this summer. Block 4 represents a major modernization phase for the F-35 program, introducing upgrades in sensors, electronic warfare, weapons integration, and survivability. These improvements are built on the Technology Refresh 3 (TR-3) hardware, which provides increased processing power, memory, and display capabilities necessary for future combat requirements. The full set of Block 4 capabilities is expected to be delivered in phases, with completion projected for the early 2030s.Follow Army Recognition on Google News at this link
The Block 4 represents a major modernization phase for the F-35 program, introducing upgrades in sensors, electronic warfare, weapons integration, and survivability. (Picture source: US DoD)
The Technology Refresh 3 (TR-3) hardware forms the foundation for Block 4, equipping the aircraft with a new integrated core processor that offers 25 times more computing power than the previous system. This enables more advanced sensor fusion, artificial intelligence-assisted decision-making, and high-bandwidth data processing. Expanded memory and storage allow for faster mission system updates and support for larger data sets used in sensor processing and threat identification. The TR-3 upgrade also introduces a high-resolution panoramic cockpit display, improving situational awareness. To manage the increased power and cooling demands of these new systems, enhanced power and thermal management solutions have been incorporated.
The Block 4 upgrade includes a new sensor suite, beginning with the AN/APG-85 Active Electronically Scanned Array (AESA) radar, which replaces the AN/APG-81. This radar provides increased detection range, higher resolution, and improved electronic warfare capabilities, allowing for enhanced air-to-air and air-to-ground operations. Additionally, it offers improved synthetic aperture radar (SAR) performance for precision targeting and reconnaissance. The Distributed Aperture System (DAS) has been replaced with Raytheon’s Next-Generation DAS starting from Lot 15 aircraft, improving thermal management, resolution, and latency.
This system provides real-time 360-degree infrared imagery for missile warning, night operations, and situational awareness. Electronic support measures (ESM) have also been expanded, increasing the aircraft’s ability to detect, track, and classify enemy radar signals across a broader frequency spectrum. The Remotely Operated Video Enhanced Receiver (ROVER) capability is being integrated to allow real-time video and targeting data transmission to ground forces.
Weapons integration in Block 4 expands the F-35’s operational capabilities. The upgrade enables the use of the AIM-260 Joint Advanced Tactical Missile (JATM), which is intended to replace the AIM-120 AMRAAM and counter long-range air-to-air threats such as the Chinese PL-15 and Russian R-77M. European customers will have the option to integrate the MBDA Meteor, a long-range beyond-visual-range (BVR) missile designed to improve engagement capabilities. In the air-to-ground role, Block 4 allows the F-35 to carry the AGM-88G Advanced Anti-Radiation Guided Missile-Extended Range (AARGM-ER) for Suppression of Enemy Air Defenses (SEAD) and Destruction of Enemy Air Defenses (DEAD).
The Joint Strike Missile (JSM), developed by Norway and Australia, is being integrated for long-range anti-ship and land attack missions. The GBU-53/B StormBreaker (SDB II) provides an all-weather, multi-mode seeker capability for precision strikes. Additionally, the F-35A has been certified to carry the B61-12 nuclear bomb as of October 2023. The Sidekick weapon rack is expected to increase the internal missile capacity of the F-35A and F-35C from four to six AIM-120 AMRAAMs.
The Technology Refresh 3 (TR-3) hardware forms the foundation for Block 4, enabling more advanced sensor fusion, artificial intelligence-assisted decision-making, and high-bandwidth data processing. (Picture source: US DoD)
Electronic warfare and survivability improvements in Block 4 include updates to the AN/ASQ-239 Barracuda system, enhancing radar jamming, electronic countermeasures, and passive detection of enemy radar signals. The upgrade incorporates new low-observable materials and coatings to improve durability while maintaining the aircraft’s stealth characteristics. The ThNDR (Threat Nullification Defensive Resource) system, a laser-based infrared countermeasure, is also being integrated to enhance protection against infrared-guided threats.
To support these advancements, the F-35’s propulsion system is receiving upgrades. The Pratt & Whitney F135 Engine Core Upgrade (ECU) increases thrust and fuel efficiency while improving cooling capability by 50% to support the additional power demands of Block 4. Although adaptive cycle engine concepts were considered under the Adaptive Engine Transition Program (AETP), the XA100 adaptive cycle engine was not selected due to cost and integration concerns.
The implementation of Block 4 is structured in phases, with some capabilities being integrated as they become available. The release of the TR-3 software package, expected later this year, will enable full combat capability, including the clearance of the Joint Strike Missile on Norwegian F-35s and the Small Diameter Bomb II (SDB II) on F-35B and F-35C variants. However, uncertainties remain regarding the timeline for full TR-3 certification, with the Joint Program Office (JPO) estimating completion by fall 2025, while Lockheed Martin officials suggest it may extend into early 2026.
The Block 4 update is expected to be applied across the entire F-35 fleet. All aircraft produced from Lot 15 onward will receive these enhancements, and customers who have already taken delivery of these aircraft will also be eligible for the upgrade. Although there has been speculation about export restrictions, the update is planned to be fleet-wide and available to all operators.
Discussions on future F-35 upgrades beyond Block 4 are ongoing. Lockheed Martin and the JPO are assessing potential capabilities for Block 5 and later versions, with priorities expected to include further enhancements to sensors, electronic warfare, and weapon systems. Some technologies developed for the F-22, such as infrared search-and-track (IRST) systems and low-drag stealth fuel tanks, are being evaluated for possible integration. However, no final decisions have been made regarding their inclusion.
Furthermore, the Government Accountability Office (GAO) has recommended that Block 4 be treated as a separate major defense acquisition program to improve oversight. The GAO has pointed out that delays and cost overruns in Block 4 do not trigger the same accountability measures as other programs due to the overall size of the F-35 budget. The Joint Program Office maintains that Block 4 is essential for maintaining the F-35’s capabilities in evolving combat environments.
{loadposition bannertop}
{loadposition sidebarpub}
As reported by Air & Space Forces on March 10, 2025, Lockheed Martin is set to begin releasing the first software updates for the F-35 Block 4 upgrade this summer. Block 4 represents a major modernization phase for the F-35 program, introducing upgrades in sensors, electronic warfare, weapons integration, and survivability. These improvements are built on the Technology Refresh 3 (TR-3) hardware, which provides increased processing power, memory, and display capabilities necessary for future combat requirements. The full set of Block 4 capabilities is expected to be delivered in phases, with completion projected for the early 2030s.
Follow Army Recognition on Google News at this link
The Block 4 represents a major modernization phase for the F-35 program, introducing upgrades in sensors, electronic warfare, weapons integration, and survivability. (Picture source: US DoD)
The Technology Refresh 3 (TR-3) hardware forms the foundation for Block 4, equipping the aircraft with a new integrated core processor that offers 25 times more computing power than the previous system. This enables more advanced sensor fusion, artificial intelligence-assisted decision-making, and high-bandwidth data processing. Expanded memory and storage allow for faster mission system updates and support for larger data sets used in sensor processing and threat identification. The TR-3 upgrade also introduces a high-resolution panoramic cockpit display, improving situational awareness. To manage the increased power and cooling demands of these new systems, enhanced power and thermal management solutions have been incorporated.
The Block 4 upgrade includes a new sensor suite, beginning with the AN/APG-85 Active Electronically Scanned Array (AESA) radar, which replaces the AN/APG-81. This radar provides increased detection range, higher resolution, and improved electronic warfare capabilities, allowing for enhanced air-to-air and air-to-ground operations. Additionally, it offers improved synthetic aperture radar (SAR) performance for precision targeting and reconnaissance. The Distributed Aperture System (DAS) has been replaced with Raytheon’s Next-Generation DAS starting from Lot 15 aircraft, improving thermal management, resolution, and latency.
This system provides real-time 360-degree infrared imagery for missile warning, night operations, and situational awareness. Electronic support measures (ESM) have also been expanded, increasing the aircraft’s ability to detect, track, and classify enemy radar signals across a broader frequency spectrum. The Remotely Operated Video Enhanced Receiver (ROVER) capability is being integrated to allow real-time video and targeting data transmission to ground forces.
Weapons integration in Block 4 expands the F-35’s operational capabilities. The upgrade enables the use of the AIM-260 Joint Advanced Tactical Missile (JATM), which is intended to replace the AIM-120 AMRAAM and counter long-range air-to-air threats such as the Chinese PL-15 and Russian R-77M. European customers will have the option to integrate the MBDA Meteor, a long-range beyond-visual-range (BVR) missile designed to improve engagement capabilities. In the air-to-ground role, Block 4 allows the F-35 to carry the AGM-88G Advanced Anti-Radiation Guided Missile-Extended Range (AARGM-ER) for Suppression of Enemy Air Defenses (SEAD) and Destruction of Enemy Air Defenses (DEAD).
The Joint Strike Missile (JSM), developed by Norway and Australia, is being integrated for long-range anti-ship and land attack missions. The GBU-53/B StormBreaker (SDB II) provides an all-weather, multi-mode seeker capability for precision strikes. Additionally, the F-35A has been certified to carry the B61-12 nuclear bomb as of October 2023. The Sidekick weapon rack is expected to increase the internal missile capacity of the F-35A and F-35C from four to six AIM-120 AMRAAMs.
The Technology Refresh 3 (TR-3) hardware forms the foundation for Block 4, enabling more advanced sensor fusion, artificial intelligence-assisted decision-making, and high-bandwidth data processing. (Picture source: US DoD)
Electronic warfare and survivability improvements in Block 4 include updates to the AN/ASQ-239 Barracuda system, enhancing radar jamming, electronic countermeasures, and passive detection of enemy radar signals. The upgrade incorporates new low-observable materials and coatings to improve durability while maintaining the aircraft’s stealth characteristics. The ThNDR (Threat Nullification Defensive Resource) system, a laser-based infrared countermeasure, is also being integrated to enhance protection against infrared-guided threats.
To support these advancements, the F-35’s propulsion system is receiving upgrades. The Pratt & Whitney F135 Engine Core Upgrade (ECU) increases thrust and fuel efficiency while improving cooling capability by 50% to support the additional power demands of Block 4. Although adaptive cycle engine concepts were considered under the Adaptive Engine Transition Program (AETP), the XA100 adaptive cycle engine was not selected due to cost and integration concerns.
The implementation of Block 4 is structured in phases, with some capabilities being integrated as they become available. The release of the TR-3 software package, expected later this year, will enable full combat capability, including the clearance of the Joint Strike Missile on Norwegian F-35s and the Small Diameter Bomb II (SDB II) on F-35B and F-35C variants. However, uncertainties remain regarding the timeline for full TR-3 certification, with the Joint Program Office (JPO) estimating completion by fall 2025, while Lockheed Martin officials suggest it may extend into early 2026.
The Block 4 update is expected to be applied across the entire F-35 fleet. All aircraft produced from Lot 15 onward will receive these enhancements, and customers who have already taken delivery of these aircraft will also be eligible for the upgrade. Although there has been speculation about export restrictions, the update is planned to be fleet-wide and available to all operators.
Discussions on future F-35 upgrades beyond Block 4 are ongoing. Lockheed Martin and the JPO are assessing potential capabilities for Block 5 and later versions, with priorities expected to include further enhancements to sensors, electronic warfare, and weapon systems. Some technologies developed for the F-22, such as infrared search-and-track (IRST) systems and low-drag stealth fuel tanks, are being evaluated for possible integration. However, no final decisions have been made regarding their inclusion.
Furthermore, the Government Accountability Office (GAO) has recommended that Block 4 be treated as a separate major defense acquisition program to improve oversight. The GAO has pointed out that delays and cost overruns in Block 4 do not trigger the same accountability measures as other programs due to the overall size of the F-35 budget. The Joint Program Office maintains that Block 4 is essential for maintaining the F-35’s capabilities in evolving combat environments.
