HILL AIR FORCE BASE — Two years after Hill Air Force Base’s F-35s were declared ready for limited combat, pilots there say their confidence in the jet is now at an all-time high.

According to a press release from Hill, maintainers on base launched 40 sorties a day for four consecutive days last week, without building any down time into the flying schedule. Typically, on legacy aircraft like F-16s and F-15s and especially with newer, next generation jets like the F-35, maintenance losses are programed into flying schedules to account for potential issues.

“We haven’t done this before and we wouldn’t even be trying it if we didn’t have the confidence in the jet,” Chief Master Sgt. Eric Engel, superintendent of Hill’s 466th Aircraft Maintenance Unit, said in the release. “The data we have backs us up.”

The Air Force gave the first batch of Hill F-35s an “initial operational capability” designation on Aug. 2, 2016. The IOC tag meant that Hill’s two fighter wings met the minimum operational capabilities to use the jet for normal combat operations.

Since that time, Hill pilots have taken the jets on several combat training missions and foreign deployments, but the jet has encountered some service problems.

Most notably, a fuel tank problem grounded 10 of Hill’s F-35s for nearly three months in 2016. The planes were grounded that September after maintenance workers on base found the cooling line insulation inside some F-35 fuel tanks had been peeling and crumbling. The Air Force said a parts supplier was responsible for the problem and the jets were fixed and back flying by November.

And until February of this year, the jets were still limited in their operating capability.

That changed with the release of new software, known as “3F,” which drove a large increase in the F-35’s capacity. In addition to a beefed up weapons package, the plane’s gravitational force was expanded to 9 Gs and targeting, mapping and the integration of all those systems was improved.

“We’ve seen an exponential increase in capability,” Lt. Col. Yosef Morris, commander of Hill’s 4th Fighter Squadron, said in the release. “At IOC, the jet was very capable doing a very limited mission set. Now we have our full inventory of weapons and we routinely train against high-end threats.”

Lt. Col. Michael Albrecht, 388th Fighter Wing director of staff and an F-35 pilot since 2011, said the technology will continue to expand, something that should dovetail nicely with a group of young but capable pilots and maintainers on base. There’s now a growing group of pilots at Hill who have flown nothing but the F-35.

In the early stages of the plane’s history at Hill, most pilots transitioned over from legacy aircraft like the F-16.

“It’s like handing my kids an iPhone and they use it and show me all kinds of things I didn’t know I could do,” Albrecht said of the group. “It’s so intuitive for these young pilots because they’ve grown up with technology. They are going to be able to get the most out of the jet.”

In July, the base received its 39th F-35 — halfway to its full complement of 78 aircraft. The 388th Fighter Wing’s Public Affairs office said nearly 8,000 sorties have been launched since the first two jets touched down in September 2015.

Since the initial delivery in late 2015, the base has been accepting one to two aircraft each month. Once the full fleet of 78 Lightning IIs is complete, which is expected sometime in 2019, the planes will be divided among three fighter squadrons.