EDWARDS AIR FORCE BASE, Calif. — Here at the F-35 integrated test force, pilots spend their days simulating real missions to prepare the jets to one day operate on the battlefield.

Defense News got a glimpse into the day-to-day life of an F-35 test pilot during a May 4 visit to Edwards Air Force Base. We followed Maj. Raven LeClair, assistant director of operations for the 461st flight test squadron, as he zipped up his flight suit, climbed into the cockpit, taxied to the runway and finally took off into the clear, desert sky.

Around 10 a.m., LeClair walked out to begin checking his jet, which was loaded with a version of the Block 3F software that will eventually give the plane its full combat capability. AF-3 was set to fly a captive carry missile test using AIM 9X and AIM 120 missiles, an exercise meant to test that the loaded weapons can communicate with the jet's main computer.

The first sign of trouble was the appearance of a "nuisance ICAW," which stands for indications, cautions and warnings — essentially a false indication that the 270-volt battery that powers up the aircraft had failed. The team had to restart the jet's main power plant twice to get the false warning light to go away.

AF-3, Major Raven "Rost" LeClair, Pre-Flt & Take Off, Defence News Reporter(Laura Seligman) F-35 ITF Edwards AFB, Ca., 4 May 2016

Maj. Raven "Rost" LeClair checks his F-35 jet before takeoff.

Photo Credit: Darin Russell

Then, the jet's electronic warfare system failed to power up correctly. The team tried recycling the different systems to avoid fully restarting the jet, also called a "cold iron" reset, but had little success.

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Just before 11:30 a.m., the team shut down and rebooted the jet, starting the entire process from scratch. But this time, the startup was clean, according to John Day, AF-3's flight test control engineer.

At 11:40 a.m., the pilot got a thumbs up, and Day took a bow.

"The second startup was so clean, it was ridiculous," he said.

AF-3, Major Raven "Rost" LeClair, Pre-Flt & Take Off, Defence News Reporter(Laura Seligman) F-35 ITF Edwards AFB, Ca., 4 May 2016

The test team tried recycling different systems to avoid fully restarting the jet, but eventually had to shut down and reboot AF-3.

Photo Credit: Darin Russell

LeClair finally lifted off around noon, lighting up his afterburner to cheers from the team.

But problems continued after liftoff. During the flight, one of the weapons had problems talking to the main computer, and LeClair was forced to land again so the team could reset the stores management system. AF-3 eventually completed the planned mission, but the team observed a number of "anomalies" during the flight. They plan to review the test data to determine a root cause.

AF-3, Major Raven "Rost" LeClair, Pre-Flt & Take Off, Defence News Reporter(Laura Seligman) F-35 ITF Edwards AFB, Ca., 4 May 2016

Maj. Raven "Rost" LeClair finally takes off in AF-3 after two hours on the ground.

Photo Credit: Darin Russell

The startup issues LeClair and AF-3's team experienced May 4, though just one test point, are representative of what F-35 pilots are seeing every day. Development test pilots here at Edwards have trouble booting up their jets about once out of every three flights, though in no cases did a shutdown event prevent the aircraft from eventually taking off, according to the integrated test team.

The problem revolves around a recurring glitch in the F-35 software, where the jets' systems shut down and need to be rebooted — sometimes even midair. This "choking" effect is caused in essence by a timing misalignment of the software of the plane's sensors and the software of its main computers, officials have said.

"The best analogy is you are starting up your computer and you want to use Word, Excel, PowerPoint and Outlook, and you are trying to get your work done for the day, and PowerPoint and Outlook came up but you are having an issue with Excel," said Brendan Rhatigan, director of engineering and test operations for the F-35 ITF. "So you say, I don't know what's going on, so let me X out of that, let me restart it again."

Despite ongoing challenges, the F-35 joint program office (JPO) is seeing an improvement in software stability. The JPO recently signed off on the Block 3i software, the version the US Air Force needs to declare its jets operational this year. In the meantime, JPO chief Gen. Bogdan has sent a "red team" to Edwards to investigate the root cause of the ground startup events, he told reporters recently.

Officials here expressed optimism the red team would be able to improve the software stability on the ground.