Before they became staples of the runway, bomber jackets, flight suits and protective aviator sunglasses were born in the cockpit of an early — and cold — airplane.

They were necessary in drafty flying machines with metal doors that were a struggle just to keep closed. But as aviation pioneers such as Amelia Earhart brought their style around the world, they sparked fashion trends that have been with us ever since.

The leather bomber jacket shown in the new Earhart biopic “Amelia,” starring Hilary Swank, marries function and style in a way that finicky fashion has embraced through the years, says Franco DiCarlo, executive vice president of Belstaff USA, the brand that collaborated with the filmmakers on key wardrobe pieces.

“A lot of the aviator jackets are timeless in style and they perform under a great variety of weather. . . . They say fashion is cyclical, but this is timeless,” he said.

But when the styles landed in the 1920s and ‘30s, it was uncharted territory, allowing a woman like Earhart to help craft the image and vocabulary of a flyer’s style, says “Amelia” costume designer Kasia Walicka Maimone.

“The whole history of aviation was really being invented, and part of that was inventing the new language,” she said.

At first, pilots borrowed silhouettes from horseback riders, race-car drivers and motorcyclists, later adapting jodhpurs, goggles and the zip-front leather jackets, among other items.

Early on, Earhart wore these things, too, but she had a lifelong interest in fashion so many of the more stylish, more feminine adaptations came from her. At one point, she had her own clothing line — a second career to support flying.

The movie’s director, Mira Nair, says time, effort and money went into capturing the right visuals of Earhart’s time. “We wanted to make the costumes seem as modern as they were then.”

Nair adds, “If I had the figure, I’d wear the brown-leather catsuit thing she wore.” She’ll still have her chance: Slim jumpsuits in stores this past spring are back in designer collections for 2010.

And Nair is still mulling a leather bomber and tie-up boots for her shopping list this season. “I’m pretty amazed to see what’s happening in fashion magazines. In the last six weeks, I’ve seen so many with the aviator look.”