There are  signs posted everywhere.  Park rangers give their verbal warnings.  Common sense should prevail.  But unfortunately, more and more hikers at Half Dome in Yosemite National Park don't heed the warnings that are meant to keep them safe.  Instead, they climb the mountain - beyond their abilities - and then expect the government to come rescue them.

"People are pushing their luck, trying to beat the weather, and their backup plan is to call for a rescue," said Mark Marschall, project manager for the Half Dome interim permit program. "They're not understanding what that means. We can't fly in that kind of weather. They're on their own."

Not only are these neophytes not listening to the voices in their heads that should be telling them not to exceed their skill levels, but they're being bold and rude when they do call for assistance.

Some callers tell the dispatcher they want to use their platinum credit card for the free helicopter ride some companies guarantee in an emergency. Park officials don't charge for rescues — nearly 1,000 rescues cost more than $2.5 million between 2007 and 2010 — but neither do they fly in dangerous weather.

"People make poor decisions for a lot of reasons," said Kevin Killian, deputy chief ranger. "What it comes down to is a lack of clarity in peoples' risk assessment. What is the true hazard and what are my bailout options?"