The plunge step is a simple technique for walking downhill in the snow. However, it is one of those techniques that seems relatively straight-forward in certain snow types, while difficult in others.
To do a standard plunge step, stand with your feet shoulder width apart. Bend your knees and drop your rear end. As you step down the hill during your descent, be sure to lead with the heel of your foot. The heel of your boot should be like a dagger, the pointy section of the heel slicing into the snow first.
In soft snow, this technique is relatively easy to understand. On our courses, we will often play games of Red Light/Green Light with students racing down the hill. In soft snow, everybody tends to stay on their feet and in control when we say red light. Hard snow is a different story. It's not uncommon to see people slip and fall trying to plunge step in such conditions. And sometimes it can be quite amusing to play Red Light/Green Light in such conditions...
The main reason that plunge stepping becomes more difficult in firm snow conditions is because your heel doesn't penetrate the snow as easily. Indeed, you have to be incredibly aggressive to get your heel into the snow.
In hard conditions, it's not uncommon for people to become tentative in their steps. Such movement can cause an individual to be more likely to slip as opposed to less likely. Occasionally this develops into a dangerous and frustrating cycle. A climber slips once, becomes more tentative, slips again, and becomes even more tentative, creating yet even a higher likelihood of slipping. The only way to kill this potentially hazardous cycle is to become more aggressive, stabbing your foot deeply into the snow no matter how hard it is.
Moving effectively in the snow is one of the most important things that climbers do. And learning to employ a solid plunge step in all the different kinds of conditions that you might encounter can only help you to become a faster and more solid climber.
--Jason D. Martin