The F-35 Lightning II is one of the most advanced aircraft ever built. But the technological innovation isn't just in the plane itself; it's inside the cockpit, too.

The helmets pilots wear include an advanced heads-up-display and the ability to see "through" the floor of the fighter. The helmet, built by Rockwell Collins, costs about $400,000, and every F-35 pilot gets his own personalized model.

"Kind of like with the airplane, the helmet is a pretty big leap in technology," said Lt. Col. Michael Gette, commander of the 61st Fighter Squadron, which is training operational pilots for the F-35.

"We're trying to do things with the helmet that's never been done before," he told Air Force Times.

That includes putting the fighter's heads-up-display on the helmet itself, projected onto the visor in front of the pilot's eyes.

Lockheed Martin, prime contractor for the F-35, claims having the HUD on the visor allows the pilot to immediately see information like speed, altitude, distance to target, and a host of other factors.

"It allows him to see everything that's of concern to him — his allies and his threats — above the horizon in the air-to-air arena," said Billie Flynn, a Lockheed Martin test pilot, in a video posted to the defense contractor's website.

"What it brings to the pilot is all the information that used to be on various screens in the cockpit, and it presents it to him on a display that gives him immediate situational awareness," Flynn said.

But in order to have the visual clarity so each pilot can read the information, the cameras in the helmet that project the display have to be fine-tuned specifically for each pilot.

Gette said the Air Force is getting the last few minor problems worked out.

"There have been issues," he said. "Trying to replace a fixed HUD on the glare shield with one that displays on your helmet presents new challenges."

In addition to the display, the helmet can see "through" the floor of the plane. Six sensors embedded in the skin project onto the helmet what the ground looks like below.

"It basically takes all these cameras ... and it stitches them together into one 360-degree picture," Maj. John Wilson, a pilot with the 61st, told Dutch publication Krigeren.

"I can basically look through my feet and see the ground," he said.

Gette noted the technology has been most effective when paired with night-vision capabilities.

"We have been using it on our night sorties here and it's been effective," he said. "You can maintain awareness of ground features, what the weather is on the ground."

There's an added bonus for the helmet, too, Gette said.

"It's the most comfortable helmet I've ever worn," he said. "You wear it the whole sortie long; you don't even know you have it on."