While he could be just one of the throng of ski enthusiasts in Colorado, Sethna's nature is to volunteer and rally others.
Berthoud Pass, an hour's drive from Denver, attracts flocks of "off piste" skiers and snowboarders who "earn their turns" by propelling themselves up slopes without ski lifts.
For years a ski area operated on Berthoud Pass, but financial woes prompted its closure. The chairlifts were removed in 2003.
It is also one of the most avalanche-prone locations in Colorado, Sethna says.
In the past decade an average of 11 skiers and snowboarders per year died in avalanches across the United States, according to the Colorado Avalanche Information Center. Colorado bears the unfortunate distinction of more avalanche fatalities than any other state.
That Berthoud Pass is close to Denver is both a blessing and a curse. "There are not very many places where you can kill yourself in an avalanche an hour from your bed," Sethna says. He recalls meeting people hiking up the pass without the proper gear. He would say to them, "Hey, people die here. It's serious."
But just warning those he happened to meet wasn't enough. Sethna began to ask himself, "How do we encourage people to go learn more?" The answer lay in teaching skiers the backcountry basics. So in 2004 FOBP began holding workshops to communicate the perils that accompany the joys of skiing untracked powder.
These introductory classes are free of charge. A donation to FOBP is optional. Over the past year attendance and the number of classes have increased dramatically.
Backcountry skiing is increasingly popular. Sales of alpine touring gear have nearly doubled in the past two years, according to Snowsports Industries America.
"There is an obvious need for what we do," Sethna says, pointing to the growing number of 18-to-24-year-olds venturing into the backcountry.
A young man in that age range has the highest chance of injuring himself in an avalanche, exemplifying why Sethna schedules classroom sessions at local colleges. "If we're lucky," Sethna says, "he'll be smart enough to realize he doesn't know anything."