Rock climbing film 'Free Solo' wins Oscar for best documentary feature

LOS ANGELES -- "Free Solo" climbed to the top of the Oscars, winning the Academy Award for best documentary feature on Sunday.

The film tells the story of rock climber Alex Honnold's quest to ascend the famed El Capitan rock formation at Yosemite National Park without ropes in June 2017.

Husband-and-wife directors Jimmy Chin and Elizabeth Chai Vasarhelyi were challenged by the conditions: filming Honnold without affecting his climb of 3,000 feet of sheer granite and getting sound because he was often too far from the camera.

"Hanging off the wall, I couldn't see Alex alone. I just had to trust that he was being perfect," Chin said backstage. "We also had to carry the weight of the entire production of being perfect. If we had made any mistakes, it could have been catastrophic."

Producer Evan Hayes said Honnold lives a rugged existence, so he was thoroughly enjoying his brush with Hollywood.

"He's embedded, thrilled," Hayes said. "He deserves so much of the credit for this."

Onstage, Chai Vasarhelyi thanked National Geographic, which made the film, "for believing in us and for hiring women and people of color because we only help make the films better."

"This film is for everyone who believes in the impossible," she said. "It was the work of an army."

The film has grossed more than $19 million worldwide.

In 2020, bouldering will be one of three disciplines of sport climbing contested for the first time at the Summer Olympics. Tokyo is slated to host the 2020 Games.