WASHINGTON — The F-35 program aims to use agile software development practices to ensure the Joint Strike Fighter can quickly receive fresh code to meet emerging threats, but production of new software is still lagging behind schedule, the U.S. Government Accountability Office said in a March 18 report.

In 2018, the F-35 Joint Program Office announced a plan to begin releasing small increments of software code every six months — a model it called Continuous Capability Development and Delivery.

Under C2D2, each software drop should be comprised of four increments of code. This is meant to allow F-35 prime contractor Lockheed Martin to develop software during the first phase, and then test it for defects, fix them and test again before pushing the software it to operational jets.

However, the recent software releases have been comprised of more than four increments to allow the company to tackle bugs that were repeatedly discovered during the coding process, the GAO found.

“For example, software delivered in June 2020 included 10 increments — six more than originally planned,” the GAO stated in its report. “Lockheed Martin representatives said that two of these increments were added to increase functionality and mature capabilities to avoid delays in the next software drop. However, according to contractor representatives, four of the added increments were to address software defects.”

Another software drop, which was originally scheduled for October 2020, included eight increments in total, with four modules added to address bugs, Lockheed representatives told the GAO. That release has been delayed until April 2021.

There are several reasons why software releases are falling behind schedule. For one, Lockheed does not always develop code for all required capabilities during the first increment, as originally planned. The company said this is because of “late contract awards preventing them from conducting new work, supply chain issues, and recent workforce capacity issues stemming from COVID-19 restrictions,” the report stated.

Lockheed also had trouble identifying software deficiencies before new code was released to operational F-35s, with one analysis by a third party finding that 23 percent of all defects (656 bugs total) were discovered after delivery from December 2017 to September 2020.

The program risks further disruption to its schedule as the F-35 moves through the Block 4 modernization effort, which began in 2018 to add new hardware and software to the aircraft. According to a review by the undersecretary of defense for research and engineering, future software drops planned for 2023 through 2025 “are more complex” than current releases, while the overall schedule is “high risk,” the report stated.

“Program officials stated that the program is currently reviewing the feasibility of its schedule and DOT&E officials told us that the program office is considering establishing longer time frames for each software drop, such as extending them to 1 year. Simply adding time to the development cycle, however, may not fully address the program’s challenges,” the GAO said, using an acronym for the office of the director of operational test and evaluation.

“Without a software development schedule that reflects how much work can be accomplished in each increment based on historical performance, the program office will continue to experience Block 4 development delays, and capabilities will continue to be postponed into later software drops,” the watchdog added.

In the end, those delays could lead to cost increases and capabilities becoming outdated before they ever reach the flight line.

The GAO ultimately recommended that the F-35 program office implement tools to automate the collection of data related to the software development process, making it easier for the program to identify whether Lockheed is meeting performance targets.

Lt. Gen. Eric Fick, who leads the government’s F-35 Joint Program Office, said that the Pentagon concurs with the GAO’s recommendations and is working to improve the aircraft’s software factory.

“The ability to stay ahead of our adversaries in the high-end fight is inextricably linked to our ability to deliver high-quality software to the F-35 air system at speed. Today, software quality is missing the mark which is driving increased cost and delays,” he said in a statement.

Lockheed has also taken steps to review F-35 software development, launching an independent review team in fall 2020 to lead a programwide assessment of the aircraft’s software capabilities. “This team, comprised of representatives from the JPO, Lockheed Martin, U.S. Government and industry, has made significant progress in identifying and addressing opportunities that provide quality products on time and on budget for the F-35 customer,” the company stated.

The GAO’s report echoed earlier concerns by the Pentagon’s independent weapons tester, who in 2020 questioned whether the program office would be able to put out new software releases on schedule.

“The current Continuous Capability Development and Delivery (C2D2) process has not been able to keep pace with adding new increments of capability as planned,” Robert Behler, the Pentagon’s director of operational test and evaluation, wrote then. “Software changes, intended to introduce new capabilities or fix deficiencies, often introduced stability problems and adversely affected other functionality.”

Simulation difficulties

As the F-35 grapples with software development challenges, it is also facing continued difficulties integrating the F-35 with the Joint Simulation Environment, or JSE — a key simulation technology that allows F-35 pilots to face off against complex and highly advanced threats that would be impossible to replicate in live training events.

The F-35 must complete 64 scenarios in the JSE in order to wrap up operational testing and move forward to a full-rate production decision. While the Pentagon had hoped to finish JSE development and run those tests by August 2020, “testing officials identified technical problems with the simulator,” according to the GAO.

In a response to questions from Defense News about those issues, JPO spokeswoman Laura Seal said the challenges include “the integration of high-fidelity models from multiple external organizations to create a comprehensive, realistic threat environment. … Complex interactions between the F-35 and this synthetic battlespace are also challenging, warranting significant development, test, and verification activities.”

As a result, the Pentagon has pushed off a full-rate production decision — originally scheduled for December 2019 and then delayed to early 2021 — to a still yet-to-be determined date.

The program office does not plan to provide a new date for full-rate production until it finishes a revised acquisition program baseline, which will lay out a modified schedule for the program, which the Pentagon’s lead acquisition official must then approve, Seal said.

The program office is also sponsoring an independent assessment of the JSE technical baseline, which will inform the F-35′s overall schedule and provide a target date for the completion of operational testing, Seal said.

“DOT&E officials stated they are not considering deferring any additional testing or granting a waiver to any test requirements needed for their final report,” the GAO stated.

Valerie Insinna is Defense News' air warfare reporter. She previously worked the Navy/congressional beats for Defense Daily, which followed almost three years as a staff writer for National Defense Magazine. Prior to that, she worked as an editorial assistant for the Tokyo Shimbun’s Washington bureau.

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