My two ski partners moved swiftly as we traversed a still-frozen face to reach Ruby Peak’s southeast ridge, 8 miles outside of Crested Butte, CO. As the slope steepened, I trailed behind. Below, there wasn’t much to cause concern—no trees, cliffs or rocks, plenty of snow and an open runout. Still, the non-edgable snow spiked my heart rate. I pulled a crampon off my pack, slid it into my binding, and finished the traverse. The glorious April day had gifted a green-lit forecast and bluebird skies—ideal for a corn harvest.

As I caught up to Andy Sovick and Eric Phillips, I wondered where this slope would fall on the ATES scale. Sovick, who founded Beacon Guidebooks, had helped pioneer the movement to bring the Canadian ATES (Avalanche Terrain Exposure Scale) to avalanche risk management in the United States, a classification system that goes from Class 0—non-avalanche terrain like low-angle and densely forested slopes—to Class 5: extreme terrain with very steep faces, cliffs, spines, couloirs, crevasses or overhead hazard.

Subscribe for access to this article plus the entire archive of The Ski Journal content—and receive a discount on all products.