An F-35A Lightning II assigned to the F-35A Lightning II Demonstration Team launches out to perform at the Innovation and Leadership in Aerospace Berlin, held at the Berlin Expo Center Airport, Berlin Brandenburg International Airport, June 8, 2024. (US Air Force photo by Staff Sgt. Zachary Rufus)

WASHINGTON — The Department of Defense today resumed acceptance of F-35 Joint Strike Fighter deliveries from prime contractor Lockheed Martin, ending a full year freeze that saw new production jets stuck on the tarmac at Lockheed’s Ft. Worth, Texas facility.

Two F-35A fighters were delivered, one each to Dannelly Field in Alabama and one to Nellis Air Force Base in Nevada, according to a joint statement from the F-35 Joint Program Office (JPO) and Lockheed.

As Breaking Defense first reported, the Pentagon halted deliveries of new Joint Strike Fighters from Lockheed in July 2023 due to software woes with an upgrade known as Technology Refresh 3 (TR-3). Persistent problems with TR-3 prompted officials to eventually capitulate to an interim software fix that would enable deliveries to resume.

Earlier this month, Breaking Defense reported that the first acceptance was expected to come sometime this week, and the unfreezing represents a major movement for the JSF program as it seeks to get its TR-3 tech refresh effort back on track.

Consisting of features like a more powerful processor and greater memory, TR-3 essentially serves as the backbone for a suite of forthcoming upgrades known as Block 4 — itself suffering from delays and cost growth. TR-3 was originally supposed to be ready in April 2023 and has run over budget by roughly $1 billion, according to lawmakers.

Under the new acceptance plan, jets will be delivered with interim software that facilitates training, but a second software drop that enables combat capabilities likely won’t be available for at least another year.

Despite the delivery halt, Lockheed has continued to build planes equipped with TR-3 but has been forced to warehouse them. The exact number of jets on hold is unclear, though Lockheed executives have said as many as 120 could be “undelivered” this year. Now the work to clear out the backlog begins, which could take nearly a year, according to a previous Government Accountability Office report.

As part of the delivery freeze, the Pentagon withheld $7 million for each newly-built plane, Bloomberg reported, which additionally first reported when deliveries would resume.

The frozen deliveries have proved a headache for the stealth fighter’s customers. Denmark, for example, reportedly considered repatriating F-35s based in the US for pilot training. The US Air Force, the jet’s largest customer, felt the pain as well, with Secretary Frank Kendall telling reporters in March that the lack of new stealth fighters is “hurting already.”

Which means the deliveries starting again will be welcomed across both the US and its F-35 partners.

“We have initiated a phased approach to the delivery of TR-3 F-35 aircraft,” Lt. Gen. Mike Schmidt, the JPO’s Program Executive Officer, said in the statement. “The first phase will deliver jets with an initial training capability in July and August. By the end of August, we will be delivering jets with a robust combat training capability, as we continue towards the delivery of full TR-3 combat capabilities in 2025. Our focus has been on providing our customers with aircraft that are stable, capable, and maintainable, and this phased approach does that.”

Added Bridget Lauderdale, Lockheed’s F-35 general manager, “TR-3 and Block 4 represent a critical evolution in capability and their full development remains a top priority for us. These and further software updates over the life of the program will ensure the F-35 continues to be an effective deterrent and the cornerstone of joint all-domain operations now and decades into the future.”