The F-35 software also lacks the ability to automatically calculate the time at which a weapon launched from the F-35 will impact the target, something the legacy systems are able to do. Ground forces need to know the “time on target” (TOT) to properly plan a combined arms artillery-air attack or to take cover when calling for “danger close” support strikes. Artillery, mortars, and aircraft have to be deconflicted in both time and space so that artillery rounds do not strike the aircraft as they fly over the battlefield. Artillery-fire suppression missions have to be timed to prevent enemy anti-aircraft fire against the attacking close support planes. Without an accurate TOT calculation, the essential precise timetables can’t be established. According to DOT&E, “The inability to calculate a TOT limits the ability of the F-35 to participate in [a] complex combined arms environment.” F-35 pilots must instead manually calculate the weapon’s time of flight. This not only increases the pilot’s workload, but also adds to the time it takes to complete an already complicated process. For embattled troops on the ground where every second counts, getting a TOT even a few seconds faster can mean the difference between life and death.

The new DOT&E report provided scant information about the F-35’s air-to-air capabilities. The report did note that tests were conducted by firing six AIM-120 missiles, but few details of the results beyond those discussed above were provided because the information is classified. DOT&E reported in FY 2016 that the Program Office conducted several successful shots with the missile but there were guidance failures on a few tests resulting in failed shots. The 2017 report does state that the tests revealed “key technical deficiencies in the ability of the F-35 to employ the AIM-120 weapons,” and “[t]he test team discovered several classified missile integration problems as well as pilot‑identified with the controls and displays that affected the combat capability of the F-35 to support the kill chain.” The report also says most of the air-to-air testing had to be performed using work-arounds to “mitigate limitations induced by outstanding deficiencies that compromised the combat capability of the weapons employment.” As reported in the 2016 report, such workarounds included test controllers having to identify or locate air-to-air targets for the attacking F-35, or having to correct F-35 targeting mistakes. Clearly, the AIM-120 AMRAAM is not working in the F-35, but the exact nature and depth of the multiple problems, as well as the cost and time necessary to fix them, remain unknown.

Assessing the F-35’s Field Performance

While there have been numerous problems uncovered during the laboratory-based developmental testing (over 200 of which remain unresolved), myriad more are sure to be found during operational testing. Operational tests go way beyond determining in a laboratory setting whether a weapon system can meet its design and contract specifications: they assess how well the weapon actually functions in the hands of the typical combat user and under the most realistic field combat conditions possible. In other words, it assesses operational combat suitability. The Department of Defense defines a suitable weapon system as one that “can be placed and sustained satisfactorily in field use with consideration being given to availability, compatibility, transportability, interoperability, reliability, wartime usage rates, maintainability, safety, human factors, habitability, manpower, logistics supportability, natural environmental effects and impacts, documentation, and training requirements.”

During developmental tests in 2017, the F-35 program continued to perform below expectations, which does not bode well for the coming operational test process. “Over the previous year, most suitability metrics have remained nearly the same or moved only within narrow bands, which are insufficient to characterize a trend of performance,” the DOT&E report stated. The entire fleet of 235 operationally deployed aircraft was only available and ready to perform all of the F-35’s intended multiple missions 26 percent of the time—that is, 26 percent was the “fully mission capable” rate. (Under the much less stringent criterion of being ready to fly just one of its missions, the F-35 fleet showed only 50 percent mission capable rate—a poor result that, disappointingly, hasn’t changed for more than three years and remains below the modest 60 percent single-mission availability-rate goal set by program officials.) The bottom line: even if the F-35 were combat-effective in all of its multiple missions, it would be unavailable to deliver that effectiveness when needed in battle three-quarters of the time.

The F-35 reliability and maintainability data generated through developmental testing are as bleak as the availability trends. The average flight time between unscheduled maintenance events is 44 to 82 minutes across the three F-35 variants. Time to repair each of these failures is 4.9 to 7.3 average hours. Like availability, the reliability trends show little or no improvement. These disappointing repair times are roughly two to three times worse than the current approved and contractually required operational requirement thresholds. The Joint Program Office proposes to solve this major deficiency simply by doubling the allowable repair time threshold for the F-35A and F-35C and increasing it by nearly two and a half times for the F-35B.

It is significant that the F-35 program has demonstrated little progress in improving these availability, reliability, and maintainability problems. The 50 percent one-mission availability rate has held steady since October 2014, “despite the increasing number of new aircraft.” Aircraft fresh from the factory with the latest upgrades should not require as much maintenance as early developmental aircraft with untested components. That they do suggests that the maintenance problems with the F-35 are deeply buried in the design, that the manufacturer is incapable of delivering an effective aircraft, or that the program, even at great expense, is not being adequately managed.

Evidence of this last point can be seen with the program’s inability to provide necessary spare parts. Indeed, the lack of replacement parts for the F-35 is one of the major factors affecting the low availability rates. This problem is aggravated by mismanagement. According to DOT&E, the “program has been late to stand up organic depot capabilities to repair existing parts that have failed but can be refurbished instead of being replaced with new parts.” This is all part of the much larger problem of the defense contractors building themselves permanently into their programs’ operations and maintenance budgets by creating a logistics system that only they can support. The Government Accountability Office highlighted the same problem in an October 2017 reportthat found the services had to wait an average of 172 days for F-35 spare parts through the Lockheed Martin supply chain.

However, like the B-2 and F-22 before it, the inherent and excessive complexity of the F-35 design and its long record of fabrication problems—such as inappropriate insulation in fuel tanks—suggest that the F-35’s availability problems are not limited to just parts availability.

The F-35 has often been described as a “flying computer,” and it was intended to operate as part of an extensive network of other aircraft and ground-based systems. Much of its claimed functionality depends on the complex array of sensors that are supposed to gather information from all of the planes in the same flight group to be processed by the computer (called the fusion engine) in each of the planes into a clear picture of the combat situation for all the pilots in that flight.

All of this was supposed to reduce the pilot’s workload. The test results show that in multiple cases the opposite is occurring. For example, pilots are supposed to be able to program mission-specific planning data into an Offboard Mission Support workstation. These data files are then carried out to the flight line to be loaded onto the F-35 with a Portable Memory Device. Pilots have found that it is taking too long to input and transfer mission plans this way, so instead they are choosing to manually enter their plans while sitting in the cockpit. Equally or more burdensome for the pilot are the multiple false targets and/or false threats being created by the apparently inherent inability of the F-35’s software to merge into one all of the network’s multiple, somewhat inaccurate position reports for any single target or threat. This also creates more work for the pilots as they have to figure out which targets are real and which aren’t, usually by verbally confirming them with other pilots, the very action the sensor fusion system is intended to replace.

This increase in workload extends even more seriously to the troubled Autonomic Logistics Information System, or ALIS. This is the massive and complex computer system, owned and operated by Lockheed Martin, that is used for combat mission planning, threat analysis, maintenance diagnosis, parts ordering, maintenance scheduling, and more. DOT&E reports that most of the functions work only with “a high level of manual effort by ALIS administrators and maintenance personnel.” For instance, the automatic diagnostics in the program continue to falsely report breakdowns on the aircraft, ordering parts that are not needed and forcing maintenance personnel to waste time trying to fix something they believed was broken only to find out that it wasn’t.