WASHINGTON — Nothing about the F-35 program is easy for the layperson to understand, whether it’s the jet’s logistics and sustainment enterprise, its path for future upgrades, or how the U.S. Defense Department buys the aircraft.

And Defense News’ investigation into the F-35’s remaining critical technology shortfalls, known as category 1 deficiencies, certainly dives into the minutia of technical details.

This project, “The Hidden Troubles of the F-35,” was the result of months of reporting by journalists who have spent years covering the program. It involved interviews with more than a dozen sources, both on and off the record, including officials from the F-35 Joint Program Office, prime contractor Lockheed Martin, fighter pilots, aerospace experts and other stakeholders.

Although each story gives a brief definition of what a category 1 deficiency is, we also thought it would be worth diving into the weeds in this brief primer of how the F-35 program classifies its technical problems.

What is a category 1 deficiency?

According to the definition set by the F-35 program, spelled out in documents exclusively obtained by Defense News, a category 1 deficiency is a shortfall that:

  • could cause death, severe injury or illness.
  • could cause loss or damage to the aircraft or its equipment.
  • critically restricts the operator’s ability to be ready for combat.
  • prevents the jet from performing well enough to accomplish its primary or secondary missions.
  • results in a work stoppage at the production line.
  • blocks mission-critical test points.

After Defense News began asking the F-35 Joint Program Office about its category 1 deficiencies, it decided to group them into CAT 1-As, which are problems like “loss of life, potential loss of life, [or] loss of material aircraft” that “have to be corrected within hours [or] days," according to Vice Adm. Mat Winter, the F-35′s program executive.

All of the F-35′s current deficiencies are CAT 1-Bs, which “have a mission impact with a current workaround that’s acceptable to the war fighter."

Does the F-35 program office use a different definition for the CAT 1 deficiency than the Air Force, Navy and Marine Corps?

In short, yes, and the F-35’s definition appears to include a wider variety of problems — specifically issues that block mission-critical test points or that already have some kind of a workaround in place.

The Air Force labels a problem CAT 1 if it can cause death, severe injury, or loss or major damage to the aircraft; if it restricts the ability for the aircraft to accomplish a mission; or if it results in a production line stoppage, but only if there is no known acceptable workaround — which could cause the F-35 program office to label some problems as CAT 1 when the Air Force would label it CAT 2.

However, the Air Force also defines a category 1 deficiency as a problem that "adversely affects technical, cost or schedule risks to the project or to the life cycle support of the system," a departure from the F-35 program’s definition.

The Navy and the Marine Corps have the shortest definition of a CAT 1 deficiency, but leaves much open to interpretation.

Under the definition used by those two services, a category 1 shortfall causes a “high probability” of loss of aircraft control, equipment damage or injury while trying to accomplish a mission of the aircraft, or it poses a “severe hazard” to weapon system or personnel. It also includes problems where “adequate performance [is] not obtainable” or that the operator must exert “excessive compensation” to accomplish the platform’s mission.

So these CAT 1 problems are obviously the services’ biggest priorities to fix, right?

Not necessarily.

Category 1 deficiencies are given that rating because they can include major problems that could impede a critical mission of the jet or can result in pilot injury, death or the loss of an aircraft.

But some of the F-35′s most serious problems have only been known to happen a handful of times — in situations where the aircraft was being pushed to its limits — and they have not reoccurred.

For that reason, sometimes problems with a less serious designation could have more of a day-to-day impact on operators.

For instance, the Air Force’s biggest priority is a grouping of deficiencies — all in need of small software fixes — that are related to battlefield awareness, said Maj. Darren Woodside, an F-35A pilot with the service’s F-35 integration office.

Another priority is a separate set of lower-grade shortfalls that would improve weapons employment displays and the pilot’s interfaces while targeting threats in air-to-ground missions, he said.

While none of these issues currently are category 1 deficiencies, fixing them would allow pilots to access information more easily and conduct missions more effectively.

“The individual impact of any [deficiency reports] is small, but the resolution of the group will provide a much higher level of capability,” Woodside told Defense News.

Where can I find more information?

Check out our webpage that is dedicated to this project: https://www.defensenews.com/smr/hidden-troubles-f35/.

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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