Having been a ski instructor in Alpe d'Huez for four seasons, I've spent a fair amount of my professional and free time off piste. As you're outside of the controlled area, if you do get in trouble, your rescue isn't guaranteed, which is why no mountain guide will take anyone in their group off piste without these three absolute essentials...
#1: Transceiver - The transceiver (often referred to as ‘beepers’) is an always-emitting ‘beacon’ that can be followed by any other transceiver to locate you under the snow in the event of an avalanche.
You wear it on your person, not in your bag(!), under the top layer of your clothes. Although new technology has made tranceivers very user-friendly, it’s paramount that everyone in your group knows how to use them, and practices regularly.
#2 : Snow probe - After locating a person caught in an avalanche with the transceiver, use your snow probe (a long, thin collapsible stick) to help you pinpoint their exact location by pushing the stick into the snow. This is essential before you waste valuable energy digging them out.
#3: Shovel - Once the person has been properly located, it’s down to the entire group to kick into action and get digging – time is of the essence.