With the craze for off-piste and the spread of all-mountain, free-rando and Fat skis, here are a few reminders about the famous, and absolutely essential, trio: AVD, shovel and probe.

- AVD’s, avalanche victim detectors (ARVA is a registered trade mark), have 2 functions: to send and to receive a signal. 
Before 1998 AVD’s were analogue. They have almost completely disappeared in favour of digital units with 1 to 4 aerials.

Single-aerial models are essentially analogue. For the signal to work well, the aerials must be perfectly aligned, which is not simple.

With 2 aerials, you have the direction and estimated distance, the apparatus works less well if the victim is buried quite deeply.

The 3rd aerial enables the depth to be taken into account. It is not shown on the screen, but there is no interference in reaching the depth of the victim.

At the top of the range, 4-aerial models enable more detailed searches.

- The probe must by wide enough to penetrate snow that has been packed down by the avalanche and long enough to be effective in all situations (standard: 240cm).

For the hauling system, a cable is best - 10g heavier than a rope but much stronger.

- The shovel must be suited to your size. A metal blade is preferable to plastic as it is obviously stronger for handling kilos of hard snow.

AVD, shovel and probe are inseparable and personal if you want to find your friends. Given that you will only be using it in an accident – and therefore stressful – situation, training is not a luxury.