Yet another issue has cropped up with the F-35 Joint Strike Fighter, already the most costly program in Pentagon history.

It appears that Norway’s F-35s have a unique feature that distinguishes them from other countries’ versions: a drag chute that is used to slow the landing of the jet in icy conditions.

However, the the drag chute is failing more than expected and the Royal Norwegian Air Force is working with the Pentagon to fix the issue before next winter.

“It’s not working the way we expected, and they are working on reconfiguring this capability,” Norwegian air chief Brig. Gen. Tonje Skinnarland said in an exclusive interview with Defense News on Thursday.

“That said, our experience operating the F-35 on slippery airfields is that it’s more safe and easier than with the F-16s,” she added. “With the stability of the [F-35] aircraft, it’s easier to take off and land on slippery airfields. … It’s performing extremely well.”

The F-35’s drag chute is mounted as a removable pod between the aircraft’s vertical stabilizers, according to Lockheed Martin. Activating a switch will open the pod doors and release the drag chute — a Kevlar parachute that creates drag on the aircraft, helping it to slow down more quickly in icy, high-wind conditions.

Norway has a reliability requirement of no more than one failed drag chute opening per 10,000 uses, the F-35 Joint Program Office said in a statement to Defense News.

Flight testing in 2018, as well as subsequent uses of the drag chute by Norway, have made clear that the current drag chute is not meeting that standard, necessitating a number of design modifications to the pilot chute and parachute deployment bag.

“A prototype incorporating many of these changes was validated by the Norwegian Air Force at Ørland [Main Air Station, in Norway] earlier this year, and that design is now being formalized,” F-35 JPO spokesperson Brandi Schiff stated.

“These technical changes will be tested and confirmed through a combination of ground and flight testing through February 2020 … the JPO anticipates delivering the first compliant parachutes in early Summer 2020.”

Lockheed Martin spokesman Mike Friedman said the new drag chute prototype is going through the engineering processes needed to ensure it will meet requirements, and that the company is on schedule.

Skinnarland said that it “is important for us to fix this” before the 2020-2021 winter season. However, she noted that the problem was “not a continuous challenge” and made clear that it would not prevent Norway from declaring initial operational capability for the F-35 this year and from operating the jet as planned.

Norway is currently the only country that operates the F-35 with the drag chute. Although the Netherlands has contributed about US$11 million to the development of the capability, according to FlightGlobal, it has not committed funding to buy the drag chute pods for its F-35s.

Despite the drag chute problem, the Norwegian military is officially bullish on the F-35, development issues and costs notwithstanding.

With Russia building up its anti-aircraft capabilities on the Kola Peninsula, a strip of land on its northwestern flank that borders Norway and Finland, Norway sees an opportunity to use the information gathering capabilities of its new F-35s and P-8 Poseidon submarine-hunting aircraft to be the eyes and ears of NATO.

“For Norway, the F-35 is not an air force capability in itself. It’s a more strategic, important, new capability for the joint force of Norway, for the defense of Norway and [for] our possibility to be the NATO in the north, providing our part of the deterrence threshold,” Skinnarland said.

“The performance of the aircraft — in general and in Norwegian conditions specifically — is more than expected. It’s an incredible capability. It performs extremely well in cold weather and the sensor capability and fusion is remarkable also when it comes to our challenging environment with the geography, topography and distance,” she said.

Over the next two years, the Royal Norwegian Air Force plans to check off a series of major milestones with the F-35. It will declare its F-35s operational at the end of the year after completing a deployment in November meant to validate that the jets can operate away from their home base of Ørland Main Air Station.

Norway has already amassed 15 F-35s at Ørland, as well as the trained pilots and technicians it needs for IOC. The deployment, where F-35 operators will rely on containerized versions of F-35 support systems like the Autonomic Information Logistics System, is the last requirement needed for the milestone, Skinnarland said. “We need to verify that this works.”

Then, in March, Norway’s F-35s will deploy to Iceland to conduct air policing efforts there on behalf of NATO.

Finally, by 2022, the air force will have built up enough jets, pilots and maintainers in the country that the F-35 will take over the “quick reaction alert” mission, which calls for operators to stand on a 24/7 alert and scramble, if needed, to intercept aircraft flying near Norwegian airspace. At that point, Norway will completely phase out its F-16s.