LiveLeaker w4chi posted a video of what it's like to survive an avalanche while wearing a special inflatable backpack.
It's shocking how quickly avalanches move. From the video description:
Yesterday morning we went into a zone called chocolate bowl in Brandywine snowmobile area for some snowmobile accessed snowboard laps, we decided to warm up on a run that we were familiar with. The top of the run was very wind affected and was hard and icy, but all the snow had been blown over onto the face where the video starts. Looking back I should have been more aware of localized conditions with the dangers of windslabs, but thats hindsight for ya. I slowed down at the top of the chute to have a look down it, and thats when the avalanche started. I deployed my Black diamond airbag backpack straight away but was then just along for the ride. It was crazy to feel the power of all that snow moving together. Luckily when it was all said and done my head was above the surface and I wasn't injured. It reminds me I still have a lot to learn about snow safety.
Here's a similar incident that shows the mechanism of the inflatable.