This article, originally published at 10:46 a.m. EDT March 21, 2016, has been updated to include a statement from Pratt & Whitney.

WASHINGTON — The clock is ticking down to the Air Force's deadline to declare its F-35A jets operational before the end of 2016.

Although the joint program office (JPO) and contractor Lockheed Martin still have several major hurdles to overcome, both industry and government officials are confident the team will beat the Dec. 30 cutoff date.

The Air Force can declare initial operational capability (IOC) for the F-35A when the first operational squadron is equipped with 12 to 24 aircraft, and airmen are trained, manned and equipped to conduct three basic missions: close-air support, interdiction, and suppression and destruction of enemy air defense. The Air Force has a five-month window of time between the objective date, Aug. 1, and the threshold, Dec. 30, to meet those requirements for IOC.

The team is making progress toward those requirements, but there is still a lot of work to be done. Lockheed and the JPO are lagging behind schedule to finish work on the latest version of the jet's logistics system, and the Lockheed-JPO team still needs to complete a critical software fix. On top of that, the team has to finish retrofitting the fleet with the latest structural modifications. Meanwhile, the reprogramming laboratories that build the plane's vast databanks are overloaded.

But as airmen begin to actually use the fifth-generation fighter jet, Maj. Gen. Jeffrey Harrigian, director of the F-35 integration office, sees momentum picking up. Lockheed has delivered 87 airplanes for the Air Force, and pilots at Hill Air Force Base, Utah, and Luke Air Force Base, Arizona, have flown almost 25,000 hours on the jets, Harrigian said during a March 9 interview. Operational F-35s at both Hill and Luke have successfully employed weapons; meanwhile, the Air Force deployed six jets to Mountain Home Air Force Base, Idaho, in February.

The F-35A Lightning II program took another step toward initial operational capability March 15 when two aircraft assigned to the 62nd Fighter Squadron successfully employed four laser-guided bombs on the Barry M. Goldwater Range.

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Photo Credit: Luke Air Force Base

"They are really starting to pick up momentum on how they are preparing themselves from kind of the people perspective for IOC, because at the end of the day, you can get the airplanes, but it's ultimately our airmen that are going to operate them," Harrigian said.

Pilots are beginning to understand the plane's power and maneuverability as well, he said. A Norwegian pilot at Luke recently wrote about his experience flying the plane in a March 1 blog post for Norway's Ministry of Defence. Maj. Morten "Dolby" Hanche wrote that the F-35 is capable of a significantly higher angle of attack than the F-16, providing a pilot greater authority to point the nose of the airplane wherever he wants.

Hanche criticized the plane's tendency to shake, or "buffet," at high G-loadings and high angles of attack. However, Harrigian said this buffeting is actually a good thing — pilots use these cues to help them understand where they are in the flight regime. When the F-16 initially flew, the lack of buffeting was actually seen as a negative attribute, according to Tom Lawhead, the Air Force chief of staff of the F-35 integration office.

Bleeding energy during flight can be a problem for any airplane, and the F-35 is no exception, Harrigian said. But as more pilots get into the cockpit, they will figure out the best ways to operate the plane.

"No airplane ever has enough power. I mean, I flew F-22s and we wanted more power in the airplane. So this comes down to, how do you manage your power?" Harrigian said. "Our pilots are going to figure out how to do that ."

ALIS Delays

Despite progress in the field, the Lockheed-JPO team are lagging behind in critical areas. The team hoped to declare IOC as early as Aug. 1, but have backed away from that target in recent weeks. Work on the latest version of the F-35's logistics system, the Autonomic Logistics Information System (ALIS) version 2.0.2, could delay IOC by 45 to 60 days, JPO chief Lt. Gen. Christopher Bogdan said recently.

Lockheed's Orlando Carvalho, executive vice president for aeronautics, also acknowledged in a March 15 interview that IOC could push past Aug. 1. The delay is related to integrating the Pratt & Whitney F135 propulsion system with the latest version of ALIS, he said. Pratt currently does engine maintenance on its own computing system, separate from ALIS, according to Lockheed F-35 program manager Jeff Babione.

"It's extremely important that we provide that capability to our war fighter and we want to make sure we get that right, so we are spending a little extra time, Lockheed Martin and its counterparts, working through the infrastructure to make sure we have a solid foundation that we can add that Pratt & Whitney capability on top," Babione said March 15. "While it's important we get this done within that window of time, that August to December for Air Force IOC, our primary focus is making sure that it works correctly."

Pratt is working with Lockheed to provide three key propulsion-related capabilities in ALIS 2.0.2, according to spokesman Matthew Bates. While Pratt has delivered all the data on time for these capabilities, propulsion integration testing is subject to availability of the ALIS test environment, he noted.

"We are working with the F-35 Joint Program Office and Lockheed Martin to accelerate the test schedules and to ensure an ALIS 2.0.2 release with propulsion will not impact airworthiness, aircraft and engine availability, or spare parts management," Bates said.

In an attempt to expedite the process, JPO and Lockheed set up mobile training teams to train airmen in the field to operate ALIS, Harrigian said. The program office will also set up a test of the system out at Edwards Air Force Base, California, to work out any kinks before the latest version of ALIS goes into the field, he said.

Software Stability Issues

Behind ALIS, the greatest risk to Air Force IOC is software development, as Bogdan has repeatedly said. The Lockheed-JPO team is racing to fix stability issues with the next increment of software, Block 3i, which the Air Force requires for IOC. In essence, a timing misalignment of the software of the plane’s sensors and the software of its main computers are causing a "choking" effect, where the jet’s systems shut down and have to be rebooted.

However, the team has identified the root cause and plans to flight test an updated software load at Edwards sometime in the next few weeks, officials said.

"We have put in a number of corrections for the problems that we observed on previous flight testing, so we're anxious to see how that performs, if we do in fact achieve the stability that's required for IOC, or if there's still some more work to do," Carvalho said.

Bogdan has said the JPO needs to have the software fixed by May 1 in order to meet the IOC target of Aug. 1. That leaves only about a month of wiggle room should the team find additional issues with the software after this next round of flight tests.

However, both Bogdan and Harrigian expressed confidence that this new software load will fix the stability issues. Lockheed CEO Marillyn Hewson is offering the F-35 program additional resources from elsewhere in the company to help fix the software issue in a timely manner, Babione said.

Whether the team makes the May 1 cutoff depends on if they find additional problems with the new software load, and what exactly is wrong, Babione said. Lockheed could fix simple "symbology" problems in a few days or a week, but if it takes some time to figure out the root cause, the program could see delays of a month or two.

"I think we're going to learn a lot in the next month or two on how close we are with this product, and if we need to change it we will change it again," Babione said. "If we can do that Aug. 1, outstanding, if it takes a little bit longer, we will get it done. I have complete confidence."

Reprogramming Lab Overload

Another area of risk for Air Force IOC is capacity overload at the so-called reprogramming laboratories that will build the plane’s mission data files (MDF), vast databanks of information needed for combat that can be loaded into the plane. Just one reprogramming lab is currently up and operating, and it is overwhelmed with orders from international partners as well as the US services, Bogdan said.

The MDF is a critical capability that enables the F-35 to be a "smart" plane. The MDF compiles all the information about different assets in an area — from the friendly to the threatening — in a "brick" that operators can load into the airplane as a kind of reference volume.

The US Reprogramming Lab is on track to complete MDFs 1 and 4, required by Air Combat Command for IOC, by Aug. 1, Harrigian said. The various MDFs cover different areas of the world, although exactly what regions each MDF covers is classified.

Jets at Hill are already flying with an interim MDF load in order to test out the system and provide feedback back to USRL, Harrigian said.

"They are learning, they are getting better, but there's still a demand signal there we will have to work through," Harrigian said. "We're looking to increase the numbers of labs that are out there to help the partners, to help the other services so that we balance out this load. ... It's really about making sure we have good tools for these guys so they can manipulate the data and get the files right."

The F-35A Lightning II program took another step toward initial operational capability March 15 when two aircraft assigned to the 62nd Fighter Squadron successfully employed four laser-guided bombs on the Barry M. Goldwater Range.

Photo Credit: Luke Air Force Base

Finishing Retrofit Modifications

There are a handful of modifications that still need to be retrofitted into the fleet, Babione said. But notably, the Lockheed-JPO team is well on its way to fully implementing a crucial improvement to the jet's fuel system that is required for IOC. The fuel system needed added valving and different tubing to ensure that the jet stays within its structural limits during high-G, aggressive maneuvering, Babione said.

The team finished retrofitting the first jet with the fuel system modification a few weeks ago — nine days early, Harrigian said. Two more jets are getting the modification and are expected to come out of the shop March 19. The plan is to have 12 fully retrofitted jets ready for the squadron by Aug. 1, he said.

"We don't see any problem with modifying the airplanes to support IOC," Babione said.

The Air Force's requirement for its F-35A variants is 9 Gs, the most stressful out of all the services. The F-35B's requirement is 7 Gs, while the F-35C is required to pull 7.5 Gs.

The Big Picture

Although the JPO is focused on meeting the Air Force's IOC deadline, the team is also keeping an eye on the program's trajectory into the next decade, Harrigian said. Beyond 3i, the JPO will continue to work on 3f, the software block required for full war fighting capability, which the Navy needs for IOC of its F-35Cs in 2018. Even farther out, block 4f will add crucial follow-on capabilities to keep the jet relevant into the future.

But in the meantime, F-35 pilots continue learning new capabilities of the jet each time they climb into the cockpit.