That last morning, they rode the Sass Pordoi cable car to the summit. Deep in the Dolomite Alps of Italy, Sass Pordoi, at 9,685 feet, is more for tourists and hikers than for skiers; its table-like summit is almost completely ringed by cliffs. But Shane McConkey and JT Holmes had no interest in marked ski runs. They were there for the cliffs.

Clipping in, they skated across the plateau and skied down about 300 vertical feet before traversing a slanting ledge. The snow was firm, verging on icy, so they switched their skis for crampons. It had snowed during the night, and they had already managed to trigger a small slab avalanche, which slid away from under them and roared over the side, falling hundreds of feet. They paused to collect their wits, then kept going, reaching their destination just before 2 pm.

McConkey had jumped this cliff before, in summer, and ski-BASE-ing it had been on his to-do list ever since. Now that he was pushing 40, he was checking items off that list as fast as he could.

To gauge the height of the cliff, they threw stones over the side and timed the drop. Eleven seconds later, Holmes heard one smack the scree field at the base. They guessed the cliff was about 1,400 feet tall, maybe more. Holmes remembers that the trees down in the valley looked really small, and he took comfort in that; it suggested they were high enough to pull off a stunt nobody else but them had ever done: a combined ski-wingsuit-BASE jump.

McConkey and Holmes would ski down a steep, hanging snowfield and launch themselves straight off the edge of the cliff; jettisoning their skis, they would then spread their arms and legs to open a wingsuit, a high-tech fabric garment that would allow them to fly. Steering the wingsuit with their arms, they would swoop out over the valley like flying squirrels before finally throwing their chutes to land. Two camera crews would film the whole thing for Matchstick Productions, the world’s leading maker of ski movies.

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