The F-35 Lightning II stealth fighter is the costliest military plane ever built, even coming with a helmet straight out of a science fiction movie.

Lea Gabrielle, a former Navy fighter pilot, got special clearance to go inside an F-35 cockpit and to try on the high-tech, $400,000 helmet that allows the pilot to "see through" the plane.

The F-35’s Distributed Aperture System (DAS) streams real-time imagery from six infrared cameras mounted around the aircraft to the helmet, allowing pilots to “look through” the airframe, F-35 test pilot Elliot Clemence explained.

Gabrielle didn't get to take the F-35 out for a spin, but she did get a chance to check out the cockpit from the hanger.

"With this helmet, I can essentially flip a switch inside the cockpit that allows me to see, inside my helmet, what the cameras on the plane are seeing," Gabrielle explained.

"So, for example, I'm going to turn and I'm going to look between my knees and I'm seeing straight through the floor of the airplane," Gabrielle said.

"Now, of course we know the program has run into a number of issues along the way, technical problems, as well as software glitches. And those have caused some delays," Gabrielle said. "But despite all those problems, the Department of Defense still says that the F-35 remains a top priority for the U.S. military."

"We've flown over 20,000 hours in this airplane," U.S. Air Force Chief of Staff Gen. Mark Welsh III said on "Shepard Smith Reporting." "This is not a PowerPoint slide anymore. It's a real machine. We're flying every single day. We're training pilots, we're training maintenance crews. The first operational unit will stand up next year."

"It's a real thing. It's flying, it's very capable, it's going to be an exciting addition. More importantly, it's one we have to have to be competitive in the high-end fight of the future," Welsh said.

Can we afford this? Shepard Smith asked, noting the $400 billion price tag to purchase more than 2,000 F-35s.

"It costs a lot of money to buy and operate this kind of equipment. There's no question about that," Welsh said. "The question is: Can you afford not to have it?"

Watch more above.

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