VIENNA (AP) — Norman Dyhrenfurth, a Swiss-American mountaineer and filmmaker who organized the successful American expedition in 1963 to Mount Everest that put six climbers on the summit and inspired generations of Americans, has died. He was 99.

Ditta Vogt, the sister of Dyhrenfuhth's long-time partner, Maria Sernetz, said he died Sunday in a Salzburg, Austria, hospital of natural causes.

Dyhrenfurth assembled the historic team of 19 mountaineers and scientists for the 1963 Everest Expedition that practically launched the modern U.S. mountaineering and outdoor industry by putting the first Americans on top of the world's highest peak. The U.S.-led mountaineering expedition he led included 900 porters carrying about 26 tons of food, clothing, equipment and scientific instruments.

But he also was an accomplished cameraman and director who was head of the UCLA Film School in the 1950s and worked on movies such as "Five Days One Summer" and "The Eiger Sanction," plus TV shows such as "Americans on Everest."

In the half-century since the famous American expedition, mountaineering has changed so much that it is sometimes difficult to appreciate just how adventurous it was for a team of Americans to set out in 1963 trying to climb Everest by two different routes at once.

At an American Alpine Club celebration of the climb in 2013 in San Francisco, Dyhrenfurth joined three other living members of the expedition — Jim Whittaker, Tom Hornbein and Dave Dingman — in recalling the wet leather boots, the heavy oxygen canisters and other challenges.

"Americans, when I first raised it, they said, 'Well, Everest, it's been done. Why do it again?'" said Dyhrenfurth.

But once the feat was accomplished, the reasons were obvious. Dyhrenfurth and his team of pioneering climbers — captured in a Life magazine cover story and honored by President John F. Kennedy at a White House Garden reception — came to represent the birth of mountaineering as a popular sport in the United States.

The expedition enabled Whittaker — a Seattle resident who went on to become chief executive of outdoors outfitter Recreational Equipment Inc. — to become the first American to summit Everest. He and Sherpa Nawang Gombu reached the top of the world on May 1, 1963, a decade after New Zealand's Edmund Hillary and Sherpa Tenzing Norgay made the first ascent in 1953 via the South Col, and about six weeks after another climber on the U.S. expedition, Jake Breitenbach, died in an avalanche.

Three weeks after Whittaker's ascent, the expedition enabled two other Americans, Hornbein and the late Willi Unsoeld, to become the first men ever to scale Everest via a more dangerous route on the mountain's west side. The next day, they descended by the southern route that Hillary, Whittaker and by then, two more members of the American team, had taken to the summit.

That adventure on the West Ridge, which included spending the night without sleeping bags or tents at 28,000 feet (8,534 meters), made Hornbein and Unsoeld the first men ever to traverse the world's highest peak — and cost Unsoeld nine frost-bitten toes.

Successful climbs of Everest's West Ridge remain a rare event. More people have reached the moon than successfully repeated the route taken by the pioneering pair.

Dyhrenfurth was born on May 7, 1918, in Germany to Himalayan explorers Gunter Oskar and Hettie Dyhrenfurth, who were awarded a gold medal in alpinism at the 1936 Summer Olympics in Berlin.

The family left for Austria and then settled in Switzerland in the 1920s, where they became citizens, then emigrated to the United States before the onset of World War II. Once in the U.S., Dyhrenfurth began to make a name for himself in climbing circles with some challenging ascents in Wyoming's Teton Range.

During the war, Dyhrenfurth's Army service won him U.S. citizenship. Afterward he became involved with the UCLA film school and took part in the 1952 Swiss Everest Expedition.

He worked as a cameraman for the 1960 Swiss Dhaulagiri Expedition, which led him to ask Nepal's government for a permit to climb Everest a few years later. He finally got one for 1963, and began assembling that now-famous team.

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George Jahn in Vienna contributed to this report. Biographical material in this story was written by former Associated Press Geneva correspondent John Heilprin.