However, the exact nature of these problems will remain unknown to the public, even when the deficiency itself is not classified. The F-35 Joint Program Office declined to characterize the fighter jet’s remaining seven critical deficiencies, but said in a statement that it has identified and tested fixes for each problem.

“Details of [deficiencies] — even unclassified [deficiencies] — are not publicly releasable because the information is operationally sensitive, and its release could be detrimental to U.S. and international war fighters operating F-35s worldwide,” said F-35 JPO spokeswoman Laura Seal.

Seal noted that all remaining critical deficiencies are classified as category 1B issues, which represent a “critical impact on mission readiness.” The more serious category 1A problems indicate a risk to the operator’s life.

Lockheed Martin also declined to issue additional details on the deficiencies.

“We track all F-35 deficiency reports. However, not all deficiency reports represent contractual deficiencies, but instead may represent observations or potential product improvements,” the company said in a statement.

In June 2019, Defense News published an investigation into the F-35 that detailed all 13 category 1 deficiencies on the books at the time — the first and only time a full list of F-35 critical deficiencies has been publicly released.

The program office confirmed in April 2020 that the number of critical flaws had dropped to seven, with only three deficiencies remaining from the previously released list of known problems:

• A technical problem involving the F-35′s cockpit pressure regulation system led to several incidents of extreme sinus pain, or barotrauma. In April 2020, the program office believed it would be able to resolve the problem in 2021 after flight testing the fix.
• On nights with little ambient light, the night vision camera embedded in the F-35 helmet could display horizontal green lines that could make it more difficult for pilots to land on ships. The JPO had intended to test a software update for the Generation III helmet to assess whether that could correct the issue with the hopes of declaring the deficiency solved in 2021.
• The F-35′s Northrop Grumman-made AN/APG-81 active electronically scanned array radar meets requirements, but the Navy wants to upgrade the system so that it can scan a wider area while in sea-search mode. In 2020, the program office stated that this issue would remain on the books until 2024, when a software update is made to the aircraft’s avionics equipment.

The JPO declined to comment on whether these specific deficiencies are resolved. However, Seal noted four of the seven critical deficiencies are expected to be fixed by the end of October, and another deficiency is scheduled to be fixed in early 2022 after shipboard tests.

The program has not set timelines for resolving the remaining two deficiencies, which “are in work pending test schedules,” Seal said.

The Government Accountability Office recommended the program fix all of the F-35′s critical deficiencies before the Pentagon approves full-rate production, an action the watchdog said would “reduce the potential for additional concurrency costs stemming from continuing to produce aircraft before testing is complete.”

While the Defense Department has concurred with that recommendation, the timeline for a Milestone C decision — which precedes full-rate production — has faced significant delays.

Operational testing must be complete before the Pentagon can make a Milestone C determination. However, that testing is at a standstill while the program office finishes work on the Joint Simulation Environment, a virtual environment that replicates adversarial threats — including highly realistic versions of enemy aircraft and weaponry — that are too complex to be simulated in live training.

The Defense Department intended to complete F-35 simulator testing in advance of a full-production decision in 2019, but testing officials discovered technical problems with the simulator and have not been able to complete the 64 tests requiring the Joint Simulation Environment.

The program could release an updated simulator test schedule as early as August, the GAO stated in a July 13 report. “Until this happens, the full-rate production date remains undetermined,” the GAO said.

Aside from the major category 1 deficiencies, the program is tracking 850 category 2 deficiencies — minor problems that represent a “possible impediment or constraint to successful mission accomplishment,” Seal said.

Of the 850 minor issues, 165 are classified as “enhancements,” meaning they do not represent a deviation from the program’s requirements like most reported deficiencies. These features are typically seen as proposed future upgrades, Seal said.

When pilots conduct supersonic intercepts or find themselves needing to race away from an enemy during combat, they will be able to take the F-35 to its furthest limits of speed and altitude — most likely without any permanent damage to the aircraft, he told Defense News in an exclusive interview.

Last June, Defense News revealed that the Pentagon had instituted time limits on the number of seconds the F-35B short-takeoff-and-landing variant and the F-35C carrier variant could spend at supersonic speeds.

Those limits were imposed after two separate tests in 2011 where the “B” model incurred “bubbling [and] blistering” of its stealth coating and the “C” model suffered “thermal damage” to the tailboom and horizontal tail, according to documents exclusively obtained by Defense News.

But those limitations must be placed in context, said Billie Flynn, the Lockheed Martin test pilot who flew both of those missions during F-35 developmental testing at Naval Air Station Patuxent River in Maryland.

According to the documents, both incidents took place during flutter tests where the B and C models were flying at speeds of 1.3 Mach and 1.4 Mach. However, that damage didn’t occur in a vacuum, Flynn said. It materialized after F-35B and F-35C test articles flew repeated supersonic runs that pushed to the plane’s maximum of 1.6 Mach, making it the result of cumulative pressures on the aircraft.

“I was flying out at 700 knots in the C model up and down the East Coast of the state of Maryland and Delaware — that’s where we fly at Pax River — and then out over the ocean, firing missiles at almost 1.6 Mach as we cleared out the weapons for the airplane. That’s extreme speed, and that’s repeated flights in those environments,” said Flynn, who has flown more than 800 hours in all three F-35 variants.

“Make a run at 700 knots, make another run at 700 knots, go to an aerial refueling tanker, get fuel for myself … and then race out again and again and again. Repeat this cycle for four- and five-hour missions,” he added.

Similarly, the flights for the B model involved aggressive maneuvering at the edge of the aircraft’s flight envelope for hours at a time.

“Nobody is going to do [that] tactically,” he said. “There’s not a combat scenario where that is going to happen.”

Although Flynn, like all fighter pilots, ended missions by walking around the aircraft and inspecting the jet for damage, he doesn’t remember seeing the blistered stealth coating or thermal damage noted in the Pentagon’s deficiency report.

Instead, Flynn offered the possibility that the degradation was only visible to engineers monitoring the internal impacts to the F-35B and F-35C test planes, which are specially equipped to measure imperceptible damage to the jet’s structure and give insight into how forces such as gravity and heat will affect it over time.

“I don’t know if I really ever saw much after a flight. I just knew that our engineers had told us about [the problem],” he said. “So an engineer whose specialty is structures would see that it would be hotter than they predicted, which would lead them to tell us: ‘If this airplane is going to last 40 years long, then we have to manage this exposure.’ ”

An operational context

When Defense News first reported on the F-35’s limits on supersonic speeds in 2019, they were classified by the Pentagon as two separate category 1 deficiencies, representing the most serious type of technical issue.

The Defense Department considers the issue “closed” as of December 2019 despite no plan to correct the problem. The F-35 Joint Program Office explained that “the operator value provided by a complete fix does not justify the estimated cost of that fix.”

Still, the documents obtained by Defense News stated that F-35C supersonic intercept missions may be impossible. Simulator testing showed that restricting supersonic flight at full afterburner to a maximum of 50 seconds could prevent the C model from reaching the 1.44 Mach endpoint for weapon launches, according to the F-35 integrated test team at Patuxent River.

To cut down the risk of damage to the jet, the Pentagon imposed time limits on how long F-35B and F-35C pilots can spend at supersonic speeds in full afterburner. An F-35C can only fly at Mach 1.3 in afterburner for 50 cumulative seconds, meaning that a pilot cannot clock 50 seconds at that speed, slow down for a couple seconds and then speed back up. The F-35B can fly for 80 cumulative seconds at Mach 1.2 or for 40 seconds at Mach 1.3 without risking damage.

The time requirements reset after the pilot operates at military power — an engine power setting that allows for less speed and thrust than afterburner — for a duration of three minutes.

By abiding by those time restrictions, the U.S. military ensures the F-35 lasts the entirety of its planned service life and that the fleet isn’t overly taxed during normal training and operations, Flynn said.

But in wartime, Flynn said, pilots will do whatever is needed “to survive and to be effective” — even if that means disregarding time restrictions and pushing the plane to its maximum performance.

Supersonic flight is not a major feature baked into F-35 tactics, the capability would likely only be used in cases when it is absolutely necessary to intercept another aircraft or in emergency situations, said Bryan Clark, an analyst with the Hudson Institute and a retired naval officer.

“It’s capable of it,” he told Defense News in April, “but when you talk to F-35 pilots, they’ll say they’d fly supersonic in such limited times and cases that — while having the ability is nice because you never know when you are going to need to run away from something very fast — it’s just not a main feature for their tactics.”

In fact, flying at supersonic speeds could minimize one of its greatest features — stealth — particularly if the jet were to do it for a long time, Clark said.

“It takes you out of stealthiness, it burns gas like crazy, so you lose the range benefits of a single engine and larger fuel tank. When you go into afterburner, you are heating up the outside of your aircraft,” he explained.

The stealthy F-35 is supposed to be able to penetrate into contested areas and destroy foes without detection, but naval aviation has little experience with low-observable aircraft and has a historical distrust of relying on long-range kills. When told about the deficiencies last year, one retired naval aviator expressed concern about the ability of F-35 pilots to move safely out of a contested area.

“The solution is: ‘Hey, we’ll just limit the afterburner to less than a minute at a time,’ ” the naval aviator told Defense News. “Which, with what the aircraft is supposed to do and be capable of, that’s a pretty significant limitation.”

But fifth-generation jets like the F-35 shouldn’t be playing by fourth-generation rules, said Flynn. In other words, the F-35 doesn’t have to rely on supersonic speed to penetrate a contested area the way most legacy jets do.

“Let’s get away from the legacy mindset. We’re an aircraft that operates with impunity. We’re an aircraft that is [a low-observable] platform that operates different than every legacy platform,” he said.

“The notion that you have to stay away from someone, or you have to run someone down [because] they see you, is the wrong context for a fifth-generation fighter but is entirely the issue for a legacy [F-14] Tomcat, [F/A-18] Hornet, [F-16] Viper, [Eurofighter] Typhoon.”

David B. Larter contributed to this report.

The deficiency, first reported by Defense News in 2019, means that at extremely high altitudes, the U.S. Navy’s and Marine Corps’ versions of the F-35 jet can only fly at supersonic speeds for short bursts of time before there is a risk of structural damage and loss of stealth capability.

The problem may make it impossible for the Navy’s F-35C to conduct supersonic intercepts.

“This issue was closed on December 17, 2019 with no further actions and concurrence from the U.S. services,” the F-35 JPO statement read. “The [deficiency report] was closed under the category of ‘no plan to correct,’ which is used by the F-35 team when the operator value provided by a complete fix does not justify the estimated cost of that fix.

“In this case, the solution would require a lengthy development and flight testing of a material coating that can tolerate the flight environment for unlimited time while satisfying the weight and other requirements of a control surface. Instead, the issue is being addressed procedurally by imposing a time limit on high-speed flight.”

The carrier-launched “C” variant and the short-takeoff-and-vertical-landing “B” version will both be able to carry out all their missions without correcting the deficiency, the JPO said.

The potential damage from sustained high speeds would influence not only the F-35’s airframe and the low-observable coating that keeps it stealthy, but also the myriad antennas located on the back of the plane that are currently vulnerable to damage, according to documents exclusively obtained by Defense News.

The JPO had classified the issues for the “B” and “C” models as separate category 1 deficiencies, indicating in one document that the problem presents a challenge to accomplishing one of the key missions of the fighter jet. In this scale, category 1 represents the most serious type of deficiency.

While it may seem dire that an aircraft procured for flying at supersonic speeds will be unable to do so for extended periods, the F-35 may not need to do it that often.

For the F-35, as opposed to the F-22 where supersonic flight is baked into its tactics, the ability to fly supersonic is more of a “break glass in case of emergency” feature, said Bryan Clark, an analyst with the Hudson Institute and a retired naval officer.

“Supersonic flight is not a big feature of the F-35,” Clark said. “It’s capable of it, but when you talk to F-35 pilots, they’ll say they’d fly supersonic in such limited times and cases that — while having the ability is nice because you never know when you are going to need to run away from something very fast — it’s just not a main feature for their tactics.”

In fact, going supersonic obviates the main advantages of the F-35, Clark said. “It sort of defeats all the main advantages of the F-35,” he explained. “It takes you out of stealthiness, it burns gas like crazy so you lose the range benefits of a single engine and larger fuel tank. When you go into afterburner, you are heating up the outside of your aircraft.”

That creates all kinds of signatures that can be detected by an adversary, Clark said.

What if?

But a retired naval aviator told Defense News last year that the limitations on the afterburner could prove deadly in close-combat scenarios.

The concept of operations for the F-35 is to kill an enemy aircraft before it can detect the fighter jet, but relying on long-range kills is a perspective that, for historical and cultural reasons, naval aviation distrusts. In the Vietnam War, when air warfare began heavily relying on missiles and moved away from the forward gun, it caused a spike in air-to-air combat deaths.

The lesson naval aviation took away was to prevent the latest and greatest technology from offsetting the learning of fundamentals, and it was the impetus behind the formation of Top Gun 50 years ago, a naval strike fighter course for training and tactics development.

“The solution is: ‘Hey, we’ll just limit the afterburner to less than a minute at a time,’ ” a retired naval aviator said when told of the issue. “Which, with what the aircraft is supposed to do and be capable of, that’s a pretty significant limitation.”

Primarily it would be an issue if the aircraft had to maneuver at high speeds to avoid a missile or survive a dogfight.

The issue is compounded for the Navy, which must operate forward for months at a time, because any significant issues with coatings or the structure of aircraft would require a depot-level repair. And so a damaged aircraft would remain damaged until its host ship returns to home port, reducing the combat effectiveness of the air wing.

“We might have to be operating at sea for eight months, so if you damage something on week one, guess what? It’s damaged for the rest of the deployment,” the aviator said. “And it affects your ability to evade detection by the enemy — you just degraded that asset permanently until you can get it somewhere where it can be fixed, at great expense and time.”

Other deficiencies

Three other category 1 deficiencies have also been officially designated as “closed,” meaning they have either been fixed or the performance of the aircraft is being accepted as is, the JPO reported.

The so-called green glow deficiency has been closed out as of last July. Green glow refers to a green light emitted by the helmet-mounted display’s LED lights. That glow obstructs a pilot’s view of an aircraft carrier’s deck lights during landing operations at sea in very low light, such as that experienced at night.

The issue was closed “as a result of incorporating an improved Organic Light-Emitting Diode (OLED) Helmet Mounted Display (HMD),” the JPO told Defense News.

“The Generation III F-35 OLED Helmet Display Unit (HDU) significantly reduced the ‘green glow’ experienced by pilots during night operations. The F-35 JPO has taken delivery of the first order of F-35 OLED HDUs to support the U.S. Navy (USN) and U.S. Marine Corps (USMC), and a second order of OLED HDUs has been placed,” the office’s statement read.

An issue created when the F-35A and F-35B blow a tire, which can result in a severed hydraulic line, will remain uncorrected, the JPO statement said, but it has not come up again since the program switched tires.

“The DR [deficiency report] was closed under the category of ‘no plan to correct’ based on the fact that the landing gear system design meets all F-35 safety standards,” the statement read. “Issues related to premature bursting of tires were resolved by tire design changes during early F-35 development and no instances of dual hydraulic system loss caused by a tire burst have ever been observed on an F-35.”

And an issue that forced the F-35 to land in cold weather because of battery trouble has been fixed, the JPO said. The issue was caused by extreme cold entering the plane when the doors to the jet’s nose landing gear were open, setting off alarm bells, according to “for official use only” documents exclusively obtained by Defense News.

The cold would enter the plane and overwhelm the battery heater blanket, which is installed to keep a 28-volt battery running at peak condition. The battery would not shut down, but because of the cold, the blanket could not heat the battery as quickly as intended, triggering warning lights in the cockpit that the battery was going to fail.

A software upgrade fixed the problem, the JPO said.

“This issue was resolved on July 22, 2019 due to improvements in the battery charger’s firmware,” the statement read. “The firmware changes were developed by the battery charger supplier, and integrated and tested by Lockheed Martin and the F-35 Lightning II Joint Program Office.”

Last June, Defense News reported exclusive details about 13 major technical issues, known as category 1 deficiencies, impacting the F-35. The JPO has since quietly downgraded five of those issues to the lesser category 2.

A category 1 deficiency is defined as 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 primary or secondary missions; results in a work stoppage at the production line; or blocks mission-critical test points.

Click here for more on the hidden troubles of the F-35.

In comparison, a category 2 deficiency is of lesser concern — something that requires monitoring, but not something that should impact operations.

But downgrading the category doesn’t mean the problems are solved, said Dan Grazier, who tracks military issues for the Project on Government Oversight.

CAT 2 programs are still “definitely cause for concern. They are going to have an impact on how the aircraft performs,” Grazier said. “It really depends on what the issue is, but every design flaw has a potential issue on the mission. … You want to not have flaws, you want these things can be fixed so pilots can get out and do what they need to do.”

Aside from a few basic statements on which projects were downgraded to CAT 2, a JPO spokesperson said the office “cannot disclose any information about how these deficiencies were resolved or downgraded due to their security classification.”

The ALIS sovereign data transfer solution does not meet information assurance requirements.

The Autonomic Logistics Information System, or ALIS, provides the backbone of the F-35, used by the aircraft’s operators in virtually all stages of flying and sustaining the Joint Strike Fighter. The system is used to plan and debrief missions, order spare parts, walk maintainers through repairs, and view technical data and work orders. (A potential replacement, named ODIN, is in the works.)

But some international partners on the F-35 program have expressed concerns that data flowing through ALIS to the United States government — and to Lockheed Martin — could give both the U.S. military and the American defense contractor a window into that country’s flight operations, including when and where its F-35s are flying.

Those concerns were so high that two countries threatened to leave the program entirely if a fix was not quickly applied, according to the original documents viewed by Defense News.

That fix is now in, according to the JPO, which said that on April 29, 2019, an update to ALIS included an initial version of a new Sovereign Data Management tool.

“The SDM tool permits F-35 operators more control over the types of Prognostics and Health Management (PHM) data that are transferred to the F-35 Operations Center,” the JPO said.

Incorrect inventory data for complex assemblies continues to result in grounding conditions.

This particular deficiency involves supplies or components that, upon installation, are not actually listed and tracked in ALIS as designed. Those require specific, almost daily requests to software engineers to have data corrected in the system. While those requests can catch some problems, the issue is not always detected by the user.

These “holes,” as the JPO calls them, do not collect data on how parts are used after installation, which means a part might be breaking down from heavy use. Yet, that part won’t be flagged by ALIS as an at-risk piece.

As a result, it’s less likely that issues developing from wear and tear or a lack of replacement parts will be discovered until such an issue has become an acute problem, possibly leading to a grounding of the aircraft.

The issue was downgraded to a CAT 2 deficiency on Jan. 13, 2020, “due to ALIS data quality improvements that have been made in the two years since this DR [deficiency report] was written,” according to the JPO. “The quality improvements have reduced the frequency and magnitude of issues that have impacted operational units’ abilities to quickly release aircraft for flight following maintenance.”

The F-35B and F-35C experienced incongruous lateral and longitudinal control response above a 20-degree angle of attack.

One of the most eye-opening issues identified in the initial report was that the F-35B and F-35C models used by the Marine Corps and Navy become difficult to control when operating above a 20-degree angle of attack — which would be seen in the extreme maneuvers a pilot might use in a dogfight or while avoiding a missile.

Pilots reported the aircraft experiencing unpredictable changes in pitch, as well as erratic yaw and rolling motions when coming in at that angle of attack..

“It has random oscillations, pitch and yaw issues above [its] 20-[degree angle of attack],” a longtime naval aviator told Defense News last year. “[So] if I had to perform the aircraft — if I had to maneuver to defeat a missile, maneuver to fight another aircraft, the plane could have issues moving. And if I turn around aggressively and get away from these guys and use the afterburner, [the horizontal tail and tail boom] start to melt or have issues.”

The issue was important enough that it accounted for two CAT 1 issues, one each for the two variants impacted by the design issue.

However, the JPO downgraded this issue to a CAT 2 on May 28, 2019, for the F-35C and on July 8, 2019, for the F-35B. The solution involves “improvements in flying qualities that were implemented in software. The improvements provide pilots with an intuitive reference indication for AOA [angle of attack], which allows pilots to more quickly optimize lateral maneuvering during air-to-air maneuvering. These software improvements have been released to all F-35 operators.”

There were unanticipated thrust limits in jetborne flight on hot days.

This particular issue only occurred once, but was so significant that it was identified in the original document as the “No. 1 priority” for the Marine Corps.

The issue was identified aboard the amphibious assault ship Essex, where a Marine pilot performed what is known as a “mode four” operation. That is where the jet enters hover mode near a landing spot, slides over to a target area and then vertically lands onto the ship. It’s a key capability for the “B” model, which was designed for its short-takeoff-and-vertical-landing abilities.

The engine — working hard on a day that temperatures cracked 90 degrees Fahrenheit while trying to lift a plane that was heavier than most returning to base — wouldn’t generate the needed thrust for a safe, ideal landing. The pilot managed to land, but the issue set off alarm bells in the Marine aviation community.

The JPO initially expected a fix for this issue to be out sometime in 2019, but it wasn’t until March 2020 that a mix of nondescript “software updates and procedural adjustments” brought the “propulsion system performance back to original specified performance levels.”

In June 2019, Defense News published an investigation delving into the details of 13 previously unreported category 1 deficiencies — the designation given to major flaws that impact safety or mission effectiveness.

Following the report, five of those 13 category 1 problems have been “closed,” meaning they were eliminated or sufficiently corrected. Five were downgraded to a lower level of deficiency after actions were taken to help mitigate negative effects, and three issues remain open and unsolved, according to the F-35 program executive office.

Four additional CAT 1 problems have also since been added to the list, raising the total CAT 1 deficiencies to seven. The program office declined to provide additional details about those issues for classification reasons, but stated that software updates should allow all of them to be closed by the end of 2020.

“The F-35 Lightning II Joint Program Office is keenly aware of these existing F-35-related category 1 deficiencies and is focused on developing and implementing solutions for these issues as quickly as possible,” the program office said in response to questions from Defense News. “F-35 operator safety is the F-35 JPO’s highest priority.”

In a statement to Defense News, F-35 manufacturer Lockheed Martin confirmed the number of open category 1 deficiencies. However, the company declined to provide further information about the path to fix current issues or how earlier issues had been ameliorated.

“We are actively addressing the deficiencies and expect all to be downgraded or closed this year,” the company said.

While the overall reduction in deficiencies is a promising trend, it is also important to track how problems are solved and how quickly fixes are pushed to the rest of the fleet, said Dan Grazier, an analyst with the independent watchdog group Project on Government Oversight.

“I’m not surprised that they are continuing to find issues. This is why we are supposed to be testing weapon systems before we buy a whole bunch of them. I am a little surprised that we are finding CAT 1 deficiencies at this point during operational testing,” Grazier said.

“I think that speaks to the level of complexity with this program that it’s taken us this long to get to this point, and even after all the testing that has been done and the time and money that has gone into this that we’re still finding category 1 issues,” he added. “It shows that the program wasn’t born in the right place. It was way too ambitious from the very beginning.”

Aside from four classified problems, there remain three open category 1 deficiencies in need of a fix. There are myriad reasons for that, the program office stated.

“Reasons for delayed issue closure vary according to the complexity of the solution and the availability of test assets needed to verify the solution,” the JPO said. “The U.S. services fund the F-35 program to address a prioritized set of DRs [deficiency reports], while at the same time, develop new capabilities. It is likely that some low-priority DRs will never be resolved because of their minor impact on F-35 fleet operations does not justify the cost of resolution.”

The F-35 program office provided some details on the path forward for resolving these technical flaws, but noted that many details regarding those plans remain classified:

Spikes in the F-35 cockpit’s cabin pressure have been known to cause barotrauma, or extreme ear and sinus pain.

This problem was documented when two Air Force pilots, flying older versions of the F-35A conventional-takeoff-and-landing model, experienced ear and sinus pain that they described as “excruciating, causing loss of in-flight situational awareness, with effects lasting for months,” according to documents obtained by Defense News. The physiological event is known by the medical term barotrauma.

The F-35 Joint Program Office believes barotrauma in the jet is caused when sensors on the outer mold line of the aircraft detect “rapidly changing static pressures” that, in turn, drive very quick changes of the cockpit pressure regulator valve.

Lockheed Martin has tested a fix that proved to be successful in a laboratory setting, Lockheed program head Greg Ulmer said last year.

But flight testing of that improvement has not occurred, slowing the pace of a solution. The F-35 program office now says flight testing of a new cockpit pressure regulation system is planned for mid-2020. If all goes well, the deficiency should be completely eliminated in 2021.

On nights with little starlight, the night vision camera sometimes displays green striations that make it difficult for all F-35 variants to see the horizon or to land on ships.

On nights where there is little ambient light, horizontal green lines sometimes appear on the night vision camera feed, obscuring the horizon and making landing on a ship more dangerous.

The problem is different than the notorious “green glow” issue, caused when the F-35 helmet-mounted display’s LED lights produce a greenish luminescence that inhibits a pilot’s ability to land on an aircraft carrier on nights with very little light.

At one point, both Lockheed and the government’s program office believed both problems could be solved by the F-35 Generation III helmet that the U.S. military began fielding last year.

Although the program office no longer considers the “green glow” problem a deficiency, it appears that the new helmet did not completely solve the night vision camera issue. The program office told Defense News that it intends to develop software improvements and test them in flight later this year, but the deficiency will not be considered “closed” until at least 2021.

The sea search mode of the F-35’s radar only illuminates a small slice of the sea’s surface.

Unlike the other problems, which are the result of the contractor not meeting technical specifications or the jet not working as planned, this deficiency is on the books even though the jet’s Northrop Grumman-made AN/APG-81 active electronically scanned array radar fulfills its requirements.

Currently, the radar can only illuminate what is directly in front of it when in sea search mode. That performance is not good enough for the Navy, which wants to be able to search a wider area than is currently possible.

Although this problem can be fixed with software modifications and an upgrade to the radar’s processing power, it will continue to be on the books for some time. According to the program office, “[the] U.S. services agreed to plan for an improved radar mode, which will require the Technology Refresh-1 avionics update, for software release in [calendar year] 2024.”

‘A line in the sand’

Although Defense Department and military leaders have criticized the F-35 program for high operations and sustainment costs, the operational community has rallied around the performance of the jet, praising its advanced computing capability that allows the aircraft to mesh together data from different sensors and provide a more complete picture of enemy threats.

Brig. Gen. David Abba, who leads the Air Force’s F-35 integration office, said in March that he was comfortable with the path forward to correct open deficiencies, downplaying the impact of those issues on daily operations.

“Is it important to hold folks’ feet to the fire and make sure that we’re delivering on the capabilities that we need? Yes,” he said. But, he added, it’s also difficult to balance the need to meet a stated technical requirement against the reality of a fielded technology that may already be performing well in daily operations.

“That’s the crux of the acquisition and the delivery problem that we have,” Abba said. “When we say ‘I need this to work exactly like this,’ I’m drawing a line in the sand. If I’m a half degree on one side of that line versus the other, is it really that different? That’s where the art comes in.”

“We’ve got to kind of get over ourselves a little bit and acknowledge that we never field perfect weapon systems,” he continued. “I don’t want to diminish the fact that it’s critical that we get after open DRs, but every weapon system in the United States Air Force — and frankly around the planet — has open deficiencies. What matters is the severity of those deficiencies and ensuring that we have a robust process between government and industry to triage those and deal with them appropriately.”

Aaron Mehta and David B. Larter contributed to this report.

But the reality may be worse. According to documents exclusively obtained by Defense News, the F-35 continues to be marred by flaws and glitches that, if left unfixed, could create risks to pilot safety and call into question the fighter jet’s ability to accomplish key parts of its mission:

F-35B and F-35C pilots, compelled to observe limitations on airspeed to avoid damage to the F-35’s airframe or stealth coating. Cockpit pressure spikes that cause “excruciating” ear and sinus pain. Issues with the helmet-mounted display and night vision camera that contribute to the difficulty of landing the F-35C on an aircraft carrier.

Click here for more on the hidden troubles of the F-35.

These are some of the problems with the jet that the documents describe as category 1 deficiencies — the designation given to major flaws that impact safety or mission effectiveness.

Thirteen of the most serious flaws are described in detail, including the circumstances associated with each issue, how it impacts F-35 operations and the Defense Department’s plans to ameliorate it.

All but a couple of these problems have escaped intense scrutiny by Congress and the media. A few others have been briefly alluded to in reports by government watchdog groups.

But the majority of these problems have not been publicly disclosed, exposing a lack of transparency about the limitations of the Defense Department’s most expensive and high-profile weapons system.

These problems impact far more operators than the U.S. Air Force, Marine Corps and Navy customer base. Eleven countries — Australia, Belgium, Denmark, Italy, Israel, the Netherlands, Norway, Japan, South Korea, Turkey and the United Kingdom — have all selected the aircraft as their future fighter of choice, and nine partner nations have contributed funds to the development of the F-35.

Taken together, these documents provide evidence that the F-35 program is still grappling with serious technical problems, even as it finds itself in a key transitional moment.

And the clock is ticking. By the end of 2019, Defense Department leaders are set to make a critical decision on whether to shut the door on the F-35’s development stage and move forward with full-rate production. During this period, the yearly production rate will skyrocket from the 91 jets manufactured by Lockheed Martin in 2018 to upward of 160 by 2023.

Generally speaking, the department’s policy calls for all deficiencies to be closed before full-rate production starts. This is meant to cut down on expensive retrofits needed to bring existing planes to standard.

The F-35 Joint Program Office appears to be making fast progress, but not all problems will be solved before the full-rate production decision, said Vice Adm. Mat Winter, the Defense Department’s F-35 program executive.

“None of them, right now, are against any of the design, any of the hardware or any of the manufacturing of the aircraft, which is what the full-rate production decision is for,” he told Defense News in an interview. “There are no discrepancies that put at risk a decision of the department to approve us to go into full-rate production.”

Nine out of 13 problems will likely either be corrected or downgraded to category 2 status before the Pentagon determines whether to start full-rate production, and two will be adjudicated in future software builds, Winter said.

However, the F-35 program office has no intention of correcting two of the problems addressed in the documents, with the department opting to accept additional risk.

Winter maintains that none of the issues represent any serious or catastrophic risk to pilots, the mission or the F-35 airframe. After being contacted by Defense News, the program office created two designations of category 1 problems to highlight the difference between issues that would qualify as an emergency and others that are more minor in nature.

“CAT 1-As are loss of life, potential loss of life, loss of material aircraft. Those have to be adjudicated, have to be corrected within hours, days. We have no CAT 1-A deficiencies,” Winter said.

Instead, the deficiencies on the books all fall under category 1B, which represents problems “that have a mission impact with a current workaround that’s acceptable to the war fighter with the knowledge that we will be able to correct that deficiency at some future time,” Winter added.

Greg Ulmer, Lockheed Martin’s vice president for the F-35 program, said currently fielded F-35s are meeting or exceeding performance specifications.

“These issues are important to address, and each is well understood, resolved or on a path to resolution,” he said. “We’ve worked collaboratively with our customers, and we are fully confident in the F-35’s performance and the solutions in place to address each of the items identified.”

The status of deficiencies

According to a June 2018 report by the Government Accountability Office, the program had 111 category 1 deficiencies on the books in January 2018. By May 24, 2018, that number had decreased to 64 open category 1 problems out of a total 913 deficiencies, according to one document obtained by Defense News.

Another document obtained by Defense News noted that at least 13 issues would need to be held as category 1 deficiencies going into operational tests in fall 2018.

The 13 deficiencies include:

• The F-35’s logistics system currently has no way for foreign F-35 operators to keep their secret data from being sent to the United States.
• The spare parts inventory shown by the F-35’s logistics system does not always reflect reality, causing occasional mission cancellations.
• Cabin pressure spikes in the cockpit of the F-35 have been known to cause barotrauma, the word given to extreme ear and sinus pain.
• In very cold conditions — defined as at or near minus 30 degrees Fahrenheit — the F-35 will erroneously report that one of its batteries have failed, sometimes prompting missions to be aborted.
• Supersonic flight in excess of Mach 1.2 can cause structural damage and blistering to the stealth coating of the F-35B and F-35C.
• After doing certain maneuvers, F-35B and F-35C pilots are not always able to completely control the aircraft’s pitch, roll and yaw.
• If the F-35A and F-35B blows a tire upon landing, the impact could also take out both hydraulic lines and pose a loss-of-aircraft risk.
• A “green glow” sometimes appears on the helmet-mounted display, washing out the imagery in the helmet and making it difficult to land the F-35C on an aircraft carrier.
• On nights with little starlight, the night vision camera sometimes displays green striations that make it difficult for all variants to see the horizon or to land on ships.
• The sea search mode of the F-35’s radar only illuminates a small slice of the sea’s surface.
• When the F-35B vertically lands on very hot days, older engines may be unable to produce the required thrust to keep the jet airborne, resulting in a hard landing.

The Pentagon has identified four additional category 1 deficiencies since beginning operational tests in December 2018, mostly centered around weapons interfaces, Winter said.

“They are not catastrophic. If they were, they’d have to stop test. There’s nothing like that,” he said. “They will be straightforward software fixes. We just need to get to them.”

Those four category 1 deficiencies will likely not be fixed or downgraded before the full-rate production decision, he said. Additionally, the service will likely need more time to address the F-35B engine thrust issue and the radar’s sea search mode problem. The problems that occur when the “B” and “C” models fly in excess of Mach 1.2 will not be fixed, as they are considered to have extremely low probability of occurring during operations.

All told, Winter expects to have about nine category 1 deficiencies still on the books as the F-35 moves to full-rate production: the eight problems defined above, and whatever surprises occur as the jet continues operational tests.

The good, the bad and the ugly

Defense News shared the list of deficiencies with two senior naval aviators — one active and one recently retired — who agreed to review the document. Each offered a different perspective on the seriousness of the problems.

The recently retired aviator said some of the issues jumped off the page at him, including the cabin over-pressurization issue, given the rash of over-pressurization issues in other aircraft, including the F/A-18E/F Super Hornet, EA-18G Growler and F-22 Raptor.

But perhaps the most serious for aerial combat operations is the combination of maneuvering issues when the aircraft is operating above a 20-degree angle of attack and the issue of possible structural damage and damage to the low-observable coating when using the afterburner. That coating helps provide the F-35 a stealth capability.

“The one that stood out to me was, wait a minute, you’re telling me that the latest, greatest aircraft — [a] $100 million aircraft — can’t perform?” the retired fighter pilot said. “It has random oscillations, pitch and yaw issues above 20A?”

However, the naval aviator currently in service said the list of deficiencies did not alarm him and that, given that the F-35 is still new to the fleet, such issues are inevitable.

“That document looks like growing pains for an aircraft that we tried to do a whole lot to all at once,” the senior aviator said. “You’re going to see that if you dig back at what Super Hornets looked like for the first few years. Go back in the archives and look at [the F-14] Tomcat — think about that with the variable sweep-wing geometry, the AUG9 radar: There was a lot of new technology incorporated into the aircraft, and there is going to be growing pains.”

Other organizations have also registered concerns about the price of fixing deficiencies.

The GAO in June 2018 warned lawmakers that moving forward with full-rate producing without fixing technical issues could drive up the cost of the F-35 program.

“If the critical deficiencies are not resolved before moving to production, the F-35 program faces additional concurrency costs to fix fielded aircraft — which are currently estimated at $1.4 billion,” the GAO stated in the report.

Winter told Defense News that the program office is taking steps to try to minimize the price of fixing the fighter jet, such as bundling in corrections to deficiencies with other software and hardware updates to decrease labor costs.

However, it is unclear how much of the cost burden will be left for the taxpayers to shoulder. The program office is recording the extra expenditures associated with fixing the deficiencies, Winter said. Ultimately, it plans to bring that data into negotiations with Lockheed in the hopes of getting the company to cover those costs.

Other watchdog organizations have criticized the deficiency litigation process for its lack of transparency. In 2018, the Project on Government Oversight blasted the F-35 program after obtaining documents that showed the Joint Deficiency Review Board downgrading 19 category 1 issues to the lower category 2 rating.

Although the Defense Department has the latitude to reclassify problems that it feels aren’t serious enough to merit the category 1 moniker, the watchdog argued that there was no fix or workaround in place for 10 of those problems.

“With the revelation that officials made paperwork fixes to make these serious deficiencies appear acceptable, it seems that much of that work is being ignored in the name of political expediency and protecting F-35 funding,” the organization stated.

Winter pointed out that the program office does not have the power to waive or downgrade deficiencies, which can be written by the test community, operators or any other stakeholder in the F-35 program. Instead, deficiencies must be evaluated by the Joint Deficiency Review Board, which includes members from the program office, the Joint Strike Fighter Operational Test Team responsible for assessing the F-35 during operational tests, developmental testers located at Naval Air Station Patuxent River and Edwards Air Force Base, as well as other representatives from the armed services and industry.

The F-35’s list of ongoing technical problems are unlikely to pose an existential threat to the program given the recent progress in fixing issues, driving down the costs of the airframe and continued support on Capitol Hill for the fighter jet.

“I would put this down to, frankly, growing pains that you’d expect from a sophisticated, modern aircraft program. Nothing really stands out [as particularly troubling], primarily because they seem to be well on the way toward being addressed,” said Mark Gunzinger, a senior fellow at the Center for Strategic and Budgetary Assessments. “What has been done to address these have reduced the concerns regarding safety of flight. Doesn’t mean that there isn’t still work to be done. And it doesn’t mean new things won’t be discovered.”

The list of deficiencies as a whole is in some ways encouraging, the currently serving aviator said, because it looks like the issues are being identified by the engineers and technicians working on the program.

“I think what you see in that document is an airplane that fell behind schedule, that was rushed to get back up to schedule under immense political and industry pressure. They had a lot of next-gen[eration] technologies all at once, and they’re working through what all of that looks like together,” the aviator said.

“I don’t see anything in that document that makes me say: ‘Holy sh–, what did we buy?’ If the questions is, ‘Why does the aircraft have all these problems?’, I don’t know, it may sound trite, but it’s a really f–ing complicated machine.”

David B. Larter in Washington contributed to this story.

The Defense Department does not intend to field a fix for the problem, which influences not only the F-35’s airframe and the low-observable coating that keeps it stealthy, but also the myriad antennas located on the back of the plane that are currently vulnerable to damage, according to documents exclusively obtained by Defense News.

The F-35 Joint Program Office has classified the issues for the “B” and “C” models as separate category 1 deficiencies, indicating in one document that the problem presents a challenge to accomplishing one of the key missions of the fighter jet. In this scale, category 1 represents the most serious type of deficiency.

Click here for more on the hidden troubles of the F-35.

Both deficiencies were first observed in late 2011 following flutter tests where the F-35B and F-35C both flew at speeds of Mach 1.3 and Mach 1.4. During a post-flight inspection in November 2011, it was discovered the F-35B sustained “bubbling [and] blistering” of the stealth coating on both the right and left sides of the horizontal tail and the tail boom.

During similar tests of the F-35C in December 2011, “thermal damage” that compromised the structural integrity of the inboard horizontal tail and tail boom were apparent.

Vice Adm. Mat Winter, who leads the F-35 program on behalf of the Pentagon, told Defense News that the department has taken steps to mitigate the problem with an improved spray-on coating, but added that the government will not completely fix it — instead accepting additional risk.

As justification for the decision, Winter noted that the issue was documented while the jet was flying at the very edge of its flight envelope. He also said the phenomenon only occurred once for both the B and C models, despite numerous attempts to replicate the conditions that caused the problem.

“How often do we expect something like that to occur?” he said. “It’s very, very small.”

Greg Ulmer, Lockheed Martin’s F-35 program head, said there have been no cases of this problem occurring in the operational fleet and that incidents have been limited to the “highest extremes of flight testing conditions that are unlikely replicated in operational scenarios.”

Winter acknowledged that the deficiency could keep the Navy from accomplishing its supersonic intercept mission — as the documents charge — if similar issues were being experienced more widely across the F-35C inventory.

“If you had that performance on all of your fleet, then you would have a problem. That’s not the case,” he said.

“We have put into place what we believe are the appropriate technical fix to ensure that our F-35Cs have the full envelope and capability to do the high-speed mission, if needed. That’s where we are. Right now, our United States Navy and Marine Corps flying the sea agree with that,” he said.

The new coating, which was introduced in Lot 8, allows the jet to withstand hotter temperatures caused by the afterburner, the documents stated. Winter characterized the material as able to withstand “what we call the thermal shock wave,” but declined to specify how the coating works or how much protection it provides.

“It may be some future advanced materials that can withstand the pressure and the temperature,” Winter said. “Then we see that, and we go, ‘Hey, look, we’ve got this on the book,’ [and] we do a test check to see if that new material solves that problem.”

The Defense Department has also instituted time limits on the number of seconds the F-35B and F-35C can fly at speeds in excess of Mach 1.2 while at full afterburner.

However, those restrictions are somewhat complicated, and it is unclear how pilots are expected to monitor their compliance to the limits while in flight.

For example, an F-35C can only fly at Mach 1.3 in afterburner for 50 cumulative seconds, meaning that a pilot cannot clock 50 seconds at that speed, slow down for a couple seconds and then speed back up. However, the time requirements reset after the pilot operates at military power — an engine power setting that allows for less speed and thrust than afterburner — for a duration of three minutes.

The F-35B can fly for 80 cumulative seconds at Mach 1.2 or 40 seconds at Mach 1.3 without risking damage.

But for both the C and B models, flying at Mach 1.3 over the specified time limits poses the risk of inducing structural damage to the aircraft’s horizontal stabilizer.

It is infeasible for the Navy or Marine Corps to operate the F-35 against a near-peer threat under such restrictions, the documents acknowledge.

“Pilot observed timers are not practical/observable in operationally relevant scenarios,” one document read. Another document said that “pilots will be unable to comply with time limit in many cases due to high mission workload, resulting in lost missions due to aircraft damage.”

And when those timer violations occur, they will result in “degradation of [stealth], damage to [communications, navigation and identification] antennas, and/or significant [horizontal tail damage],” one document explained.

How significant is this problem?

The limitations on the afterburner, when combined with another deficiency pertaining to the plane’s maneuverability, could prove deadly in close-combat scenarios.

The concept of operations for the F-35 is to kill an enemy aircraft before it can detect the fighter jet, but relying on long-range kills is a perspective that, for historical and cultural reasons, naval aviation distrusts. In the Vietnam War, when air warfare began heavily relying on missiles and moved away from the forward gun, it caused a spike in air-to-air combat deaths.

The lesson naval aviation took away was to prevent the latest and greatest technology from offsetting the learning of fundamentals, and it was the impetus behind the formation of Top Gun 50 years ago, a naval strike fighter course for training and tactics development.

“The solution is: ‘Hey, we’ll just limit the afterburner to less than a minute at a time,’ ” one retired naval aviator said, when told of the issue. “Which, with what the aircraft is supposed to do and be capable of, that’s a pretty significant limitation.”

“If you want to use it on the first or second day [of a conflict], it has to be stealthy, so you can’t hang a lot of external stores, which means you have to use internal fuel and internal weapons. And that means you have to launch fairly close in and you’ve got to be close enough to do something to somebody. And that usually means you are in a contested environment,” the aviator said.

“So you’re saying that I can’t operate in a contested environment unless you can guarantee that I’m going to be however far away from the thing I’m trying to kill,” the aviator added. “If I had to maneuver to defeat a missile, maneuver to fight another aircraft, the plane could have issues moving. And if I turn around aggressively and get away from these guys and use the afterburner, it starts to melt or have issues.”

The issue is compounded for the Navy, which must operate forward for months at a time, because any significant issues with coatings or the structure of aircraft would require a depot-level repair. And so a damaged aircraft would remain damaged until its host ship return to home port, reducing the combat effectiveness of the air wing.

“We might have to be operating at sea for eight months, so if you damage something on week one, guess what? It’s damaged for the rest of the deployment. And it affects your ability to evade detection by the enemy — you just degraded that asset permanently until you can get it somewhere where it can be fixed, at great expense and time,” the aviator said.

However, a naval aviator currently in service said the afterburner problem may not be that troubling to pilots, who must frequently work around a jet’s limitations. The key, he said, is understanding how often the issue occurs.

“I think you’d do well to go back and look at all the times they used the afterburner and that didn’t happen,” he said. “We’re talking about tens of thousands of sorties at this point that this aircraft has flown.”

Other aircraft that the Navy operates also have afterburner limits, he explained.

“I think that number needs context,” he said. “It looks scary on its own, but [the Super Hornet] has afterburner limits. They’re not that restrictive, but they have them. The aircraft has an afterburner, you want it to work.

“But I would want to get context for that number: Does this represent 0.002 percent of all sorties? If that’s the case, I don’t give a sh–, and I’ll probably have 15 other things fail before that.”

Bryan Clark, previously a top aide to former Chief of Naval Operations Adm. Jonathan Greenert and now an analyst with the Center for Strategic and Budgetary Assessments, likened the limitation on the afterburner to similar restrictions on submarine and ship operations.

“I think the operational impact is not huge, since it only applies during a small fraction of the jet’s operational profile. In subs and ships, we have a ‘safe operating envelope’ that defines where the platform is engineered to operate reliably for a long time. We can operate outside the safe operating envelope for a short time, but there are risks to doing so. The operator or commander needs to balance those risks against the benefits,” he said.

“That is similar to this situation,” he added. “The pilot can be on afterburner as long as needed to evade a threat but has to know the risk of structural damage increases. The pilot can balance that against the risk of getting shot down because he or she didn’t evade fast enough.”

The most important piece will be how well trained the pilot is on the aircraft, he continued.

“As a submariner, I knew the risks of being outside the safe operating envelope and how those risks increased over time and would impact ship performance.”

The core issue, according to Defense Department documents about the F-35 program exclusively obtained by Defense News, surrounded the F-35′s logistics system, the Lockheed Martin-produced Autonomic Logistics Information System, otherwise known as ALIS.

ALIS is used by F-35 operators in virtually all stages of flying and sustaining the Joint Strike Fighter. The system is used to plan and debrief missions, order spare parts, walk maintainers through repairs, and view technical data and work orders.

But some partners on the F-35 program worried that data flowing through ALIS to the United States — and to Lockheed Martin — could give both the U.S. military and the American defense contractor a window into that country’s flight operations, including when and where its F-35s are flying.

Although several foreign F-35 customers have publicly discussed concerns about sovereign data moving through ALIS, this report marks the first time it has been disclosed that those concerns were so severe that multiple countries threatened to withdraw from the program.

“[Two-plus] countries have threatened that, if sovereign data is not addressed, they will either (a) pull out of the F-35 program of (b) stop sending any data to the U.S.,” one document states.

The documents, which are marked “for official use only,” do not specify which countries had considered dropping out. Vice Adm. Mat Winter, who has led the F-35 program since 2017, said he was unaware that any nations had made such threats.

Click here for more on the hidden troubles of the F-35.

“I don’t know where that ever came from, maybe from the politics, but there’s nobody pulling [out],” he said. “No one ever said those words to me, and I see all of my partners on a regular basis.”

It appears a solution may already be in hand.

On Aug. 17, 2018, the Defense Department awarded a $26 million contract to Lockheed Martin to develop and test an “ALIS Sovereign Data Management” system that will allow foreign partners to more tightly control and protect their own data.

That effort has borne fruit, and certain partner nations have begun using the new data guard, which rolled out earlier this year, Winter said.

“Sovereign data management has been fielded to those that have aircraft. Norway has it. Israel has it. U.K. has it. Italy has it. We’re rolling it out to the Asia-Pacific here, now,” Winter said.

According to Greg Ulmer, Lockheed’s F-35 program head, early feedback from international customers is positive.

New safeguards

The new data guard allows a foreign military to manage aspects of its data that is sent to the F-35 Hybrid Production Support Integration team, basically allowing a partner nation to review and block data leaving the country.

But the documents obtained by Defense News also mention a future iteration of the management system, which is set to be available in 2020 on a future version of the software known as ALIS 3.6. That future iteration is expected to allow countries to filter the “releaseable” data from the “nonreleaseable” data in every message.

But why might it be important for foreign nations to share certain data collected by ALIS?

Both the F-35 Joint Program Office and Lockheed use the data collected by the planes to analyze the health of the aircraft and gauge when maintenance is needed. Without it, foreign militaries could be required to perform extra inspections or work on the plane to mitigate additional safety risks. It would also hinder Lockheed’s ability to provide spare parts when needed, making it more likely that jets would be stuck on the ramp.

Although many partner nations already have the sovereign data management system, the problem is currently classified as a category 1 deficiency, the label given to technical problems of high severity. Winter could not say when the deficiency would be formally eliminated or downgraded to category 2 status, and the F-35 JPO did not provide an answer to this question by press time, despite several weeks of advanced notice.

Mark Gunzinger, a senior fellow at the Center for Strategic and Budgetary Assessments, said the sovereign data concerns raised by allies over the F-35 are a logical extension of the data security discussions that regularly occur between the United States and international countries that buy its weapons.

“It’s a two-way street,” he said, noting that the U.S. Defense Department is currently grappling with how to respond to Turkey, an F-35 partner nation that has triggered security concerns with its plans to buy the Russian S-400 air defense system.

“You can’t fault our allies and partners for expressing their concerns,” Gunzinger added. “They should certainly be expressed, and it looks like they are — just as we have expressed our concerns over other weapons systems programs, fairly recently, in fact.”

The documents stated that the concerns about ALIS sovereign data stem back to 2013, when the Australian Ministry of Defence conducted a review of ALIS data security.

“For [five] years, the international partners have highlighted the need for a sovereign data solution to ALIS,” the document states. However, the Pentagon did not recognize the problem as a deficiency until December 2016, when Todd Mellon, formerly the F-35 program office’s top civilian, directed that the issue be assigned as a category 1 deficiency.

“U.S. services are ambivalent to this issue,” the document states. But “foreign partners believe that the ability to inspect and control information coming into and leaving their country is critical to their cyber security posture.”

At the time, certain partners discussed working on their own solutions to the sovereign data issue.

The Royal Australian Air Force planned to create an interim product that would help F-35 partners protect their data and could be introduced as early as 2018, Air Vice Marshal Leigh Gordon told FlightGlobal in 2017. It is unclear whether the RAAF continued to develop that fix.

Norway and Italy stood up a software lab at Eglin Air Force Base, Florida, allowing the two nations to manage its mission data separately from the U.S. military. A spokeswoman for the Italian Air Force told FlightGlobal in 2017 that Italy was also working on hardware and software that would filter out sensitive F-35 data and keep it from being sent to the United States.

Correction 6/12/19: This story misstated the value of the sovereign data management contract, which is $26 million.