AURORA, Colo.—As Lockheed Martin prepares to release the first F-35 Block 4 software updates this summer, the company and the Joint Program Office are already well into analyses that will decide what will comprise Block 5 and later upgrades, Lockheed’s F-35 program manager said. For now though, some of the new tricks that have been added to the F-22 aren’t migrating to the F-35.
Pilots should see “a much higher increase in stability” with this summer’s Tech Refresh 3 software release, Chauncey McIntosh, Lockheed’s vice president and general manager for the F-35, said in a briefing for reporters at the AFA Warfare Symposium.
Issues with TR-3 has been a sticking point for months now. Back in mid-2023, the JPO stopped accepting deliveries of F-35s because the airplanes were being built with TR-3 systems, but TR-3 was not yet fully tested. Finally, in July 2024, program executive officer Lt. Gen. Michael Schmidt lifted the hold on deliveries, saying he was satisfied that the TR-3-equipped jets were safe to fly after the test force demonstrated less need to reboot the software in flight.
TR-3 is the hardware and software foundation of the 80 or so improvements that comprise the Block 4 upgrade. It includes a powerful new processor, expanded memory, and new displays for the F-35, among other enhancements, which will allow the F-35 to employ new targeting, navigation, communications, and electronic warfare systems, as well as new munitions.
Block 4 is “really going to be about enhancing the sensor upgrades, the sensor fusion, and also bringing the new weapons” to the jet, McIntosh said
In an interview with Air & Space Forces Magazine, McIntosh said the threat is driving continual revisions to the roadmap that lays out the top priorities for Block 4 and later improvements.
“We have to continue to advance this airplane regarding where that threat is going,” he said. “And so we’ve laid out a plan and a strategy for Block 4, and what we need to do to ensure we stay ahead of that threat.”
The TR-3 “provides the computing resources this plane needs to move us into the next generation. … So, to me, that is a check. We now have the resources needed that we can build upon the foundation for this project.”
That inevitably leads to questions about the future of the program: “We’re looking at … what do we need for Block 5? What do we need for Block 6? And it’s really taking a long view,” he said.
Both Lockheed and the JPO are studying what will be needed in future upgrades, and those will likely shift over time, McIntosh added.
“Working with the Joint Program Office, there are going to be capabilities that are higher priority, and [some] … that will continue to be important, but maybe not as high priority as number one and number two, and so that list will constantly evolve as we continue to look at what the threat is doing,” he said.
The top two priorities for now are expanded and upgraded sensors and weapons, “and that’s what you’re going to see us do for now [and] the foreseeable future, throughout Block 4 and Block 5,” he said.
Asked if Lockheed could re-use capabilities developed for the F-22—such as infrared search-and-track systems or low-drag stealth fuel tanks and pylons, McIntosh said they are being considered but have not yet been added to the list.
“That’s going to be an evaluation,” he said, “so we’re not ready to say we’re going to jump in right now, but we’re going to constantly evaluate whether it’s tanks [or] an IRST pod. Anything that the Raptor is buying down as a tech risk, we’ll evaluate. … At this point, I’m not going to say, hey, yes, we’re definitely doing something that’s Raptor-related.”
He also said there are no hard timelines for Block 5 and later programs. Some capabilities may move forward from Block 5 to 4, and some may be deferred to later blocks to allow the technology to mature. Schmidt told Congress last year that some Block 4 capabilities will be deferred by years in order to concentrate on more urgent needs.
Some Block 5 capabilities will be released during Block 4 “because we can, and the timing’s right,” McIntosh said, without disclosing those improvements. “It’s going to be continuous rollout of capability as those [capabilities] are ready.”
Eventually, the JPO will submit to Congress an “official” list of what constitutes Block 4, he said.
The Government Accountability Office has several times urged Congress to break out Block 4 as a separate major defense program from the F-35, in order to get finer resolution on its successes and delays. The GAO said that big setbacks in Block 4 don’t trip Nunn-McCurdy breaches because they represent a low percentage of the overall F-35 cost, which is in excess of $1 trillion dollars but would in any other program be major disruptions.
One Block 4 capability already resident on the F-35 is the Automatic Ground Collision Avoidance System, McIntosh said, which senses when the aircraft is headed for a crash and pulls the aircraft up and away from danger. The system has saved lives in the F-16, typically when a pilot has lost consciousness due to excessive G-forces.
“All these decisions of what capability moves right or moves left is really all about the operational analysis that we’re doing in conjunction with the government, and getting to advise them on our thoughts,” McIntosh said.
McIntosh would not comment on what capabilities might appear in Block 5 or later, other than to say they will be “the most important … because by the time we build them, we’re going to maintain that dominance over that adversary. So yes, it’s always going to be a Block 4, Block 5, Block 6,” following in the lineage of other fighter programs continually upgrading.
McIntosh repeated previous Lockheed statements that the company expects to deliver between 170 and 195 F-35s this year, having delivered a total of 110 to the U.S. and partner countries in 2024. The type reached 1 million flying hours just before the symposium.
A company official reported that nearly all the jets that were stored during the delivery hold have now been delivered.
McIntosh declined to say whether full TR-3 testing and certification will be complete this year. The JPO has predicted it will happen in the fall, but company officials have suggested it could be early 2026.