Skiing technology...

...when off piste...
Text courtesy of Wiki : at the start of the day the transceiver is activated, causing the device to emit a low-power pulsed transceiver signal. Following an avalanche, and if the holder of the transceiver is safe and has not themselves been caught by the avalanche, they may switch the transceiver from transmit into receive mode, allowing use as a radio direction finding device to search for signals coming from other skiers' transceiver who may be trapped. A 457 kHz transceiver is an active device that requires batteries. A ski suit or boots may also contain a passive RECCO transponder sewn into the clothing or attached to the boot cuff.

As you can see - we have both. The idea is that if you do get buried, you're under the snow for as short a time as possible ;) 
Thanks Skeena for an interesting mono month!